pgmfi.org

I am pre-noob on this stuff... like you I have always wanted to learn how to tune my car... I recently came across a PLX R-300 for cheap and have decided to give it a go...

I wish I had more tech savvy but am still learning....

I'm just trying to piece everything together bit by bit... then hopefully I'll get to the point where I can actually burn a functional chip!!

Thanks for the info!!

I also am a pre-noob at this stuff lol. I read your post and most of the links you references in your post, and feel confident that I can do this myself, once I get some money. Thanks!

How do you determine your target AFR? do you just shoot for stoich if you're going all motor?

You won't want to tune for stoich across the board. Engine's need more fuel when they are under load.

Please start another thread for this since I'm trying to keep this one from going on too many tangents. A search will probably yield some good data for you. Other sites with more info specific to your engine would be a good resource, too.

I actually have a few questions about target AFRs based on discussions with some pretty experienced tuners. Even the experts don't always agree completely on target AFRs. I will eventually start a separate thread on this subject with some specific questions, too.

Sorry I haven't added more Street Tuning info. I've been busy and any spare cycles have been spent to work on my DIY Electronic Boost Controller. I'm boosting about 1.5 PSI more than I have been for the last couple of years under the power of my EBC. Check it out at viewtopic.php?p=90173#90173.

The other updates are coming eventually.

Street Tuning

Disclaimer: Street Tuning is dangerous. You can hurt your motor, run into another vehicle, run your car off the road, and many other potential problems. There are a lot of things to keep track of to prevent disaster from resulting. You must keep track of RPM, MAP, AFR, watch the road, listen to the engine, etc. Please be careful! Also, I'm not a professional tuner so follow my recipe at your own risk.


Base Tune

Successful Street Tuning starts with a good base tune. A base tune is a binary you load into your ECU that will control the engine close to its required specifications.

You can acquire your base tune via a number of means. You might download one from the PGMFI Wiki, get one from [/url]http://xenocron.com/[/url], use a friend's bin file, or get one from a good tuner just as examples. You'll want to get your map from a trusted source since a bad base tune can make your life miserable at best and ruin your engine at worst.

Your base tune should match the specifications of your setup as closely as possible. You should try matching engine displacement, compression ratio, cam profile, injector size, fuel pressure, turbo setup, exhaust, and any other variable you can think of. Some of the more significant things to match are displacement, injector size, and engine type. Even an change in internals with the same block will change engine type.

You might be able to find a base tune that fits your setup very closely, or you might not. The closer you can get your base tune to your specifications, the easier, faster and safer you will be able to tune your car.

IMPORTANT: Any bin file you get from someone else should be considered a base tune unless you are running a bone stock setup with an original bin file. There are so many variables that change from setup to setup. You should verify your car runs good on any bin file before you use it permanently with complete confidence. Using a bin file that you *think* should be okay for even a short time without at least checking AFRs can easily result in a burnt down motor.

Most of the tuning guides I have seen on this site assume a good base tune. The process for tuning an engine with a base tune that is very different from the target setup is much more involved and requires more experience than newbie’s have. It’s something the tuner has to work up to by tuning cars with pretty good base tunes first.

If you read the first part of this thread you know that I used a stock P28 bin file to start with and then changed the fuel map for bigger injectors, added columns in the table for boost, etc., etc. Although compensating for larger injectors seemed simple to me, it might have been nice in retrospect to have something that already took my turbo into consideration. The aspect of my base tune that has required the most work is the change in timing I’ve had to make in the lower sections of my maps to compensate for the turbo.


Tips

Before we get too far, I'd like to list a few tips that I have picked up along the way. Some are from members of this forum, some are strictly my opinion, some may be wrong, ... you get the idea. If you follow these tips in addition to good common sense, you will hopefully be able to safely figure out the rest given enough time and experience.

* Have the best base tune you can find before you start tuning.
* Know how things work before you change anything in your bin file.
* Have a good baseline of measurement so you know how things are *supposed* to work if possible.
* Make only small adjustments at any one time.
* Only change one thing at a time.
* Have as much instrumentation as you can so you can measure what's going on. You can’t improve what you can’t measure.
* Have accurate instrumentation.
* Make your maps smooth.
* Find a good place to tune.


Making Small Adjustments

Making small adjustments will help reduce risk as you tune. You might feel that you are progressing at snail pace by making small adjustments. If so, you're doing it right!

Check all your instrumentation carefully after making adjustments to ensure that the changes you've made have improved things and not hurt them. You should already know how your change *should* affect the engine before you make it. If the change doesn't affect things the way you thought, revert your change and think things over again. Figure out why it didn't work the way you thought! The motor is *never* wrong when it starts to ping or run poorly - it's always you.

Once you get a concrete feel for how changing something affects the myriad of engine vitals and by how much, you can start changing things quicker. Obviously your tune time will decrease and you will become faster with experience. Always error on the side of small adjustments when you get into new territory or things aren't working the way you think they should.


Only Change One Thing at a Time

An engine is a very complicated collection of electrical, chemical, mechanical, thermal, pneumatic, and hydraulic systems (I'm sure I missed something in there ). There is a lot of complexity in an engine. Managing that complexity is the key to successfully tuning your car.

You may feel that things are going too slow if you only change one thing at a time. Changing one thing at a time will seem slower in the short term, but will often result in a much faster tune in the long run. It will certainly be safer.

Changing multiple things at once will often leave you guessing as to what caused a change in the engine's performance. Sometimes the two things you change will cancel each other out and seem as though they were ineffective, even if they were significant. The worst case scenario would be that changing multiple things at once causes a dramatic effect which results in a failure or permanent damage. Most commonly, changing multiple variables at one time causes confusion which results in lost time while ignorantly pursuing a lost cause. Add these detours up and you can see why it often takes longer to complete the entire tune even though it may seem slower in the short term when you only change one thing at a time.

As you gain experience and obtain a concrete understanding of how changes affect the engine, you can change more than one thing at a time. You will still have to gauge the risk of each variable you are changing. It will probably never make sense to change some things in combination. Erring on the side of changing one thing at a time will keep you safer and quicker in the long run.


Instrumentation

Having good instrumentation is crucial to safe and effective tuning. You *must* have a wide band o2 to safely and accurately tune. You might find a source or two on the Internet stating you can do it with an nbo2. Don't follow that advice! You're on your own either way.

You should be able to view and log RPM, MAP, and AFR *together* at a bare minimum. Without sampling them at the same time, each piece of data is not worth much. Having them together gives you the context you need to understand how the engine is performing. This means that tuning by watching you wbo2 separately from your tach and boost gauge is not advised. You can do things this way, but it will be riskier, take longer, and be less accurate. It's a recipe for disaster on the road while Street Tuning.

Another instrument that I highly recommend is a knock detection device of some sort. The home made det can in the Toys and Tools section of this site works well for me. It took me a while to tune my ear and brain to what detonation on this engine sounds like, but I trust it more now than an electronic device. Since detonation sounds so different for each engine, it’s difficult to build an electronic device that is properly tuned for every setup. By using a low tech, low budget det can you can save a few dollars and leverage the power of your brain, which is a powerful and adaptive device. Knock can be very difficult to hear without the aid of a det can.

Using your eyes to read plugs can be helpful. Plug reading is somewhat of an art and can be difficult if you're color blind, like me. There are some tell tale signs of problems like black peppering and balls of aluminum that should be avoided. I once had detonation so bad that the insulator on the tip of the spark plugs cracked! Something like that is an indication of severe detonation. Hopefully you never experience it. Only split seconds of detonation that severe will do fatal damage to your engine. I got lucky to only have lost a head gasket.

I have found TPS and tach data to be helpful at times. Vehicle speed might be interesting if you have a lot of wheel spin problems. Speedometer info can also be used in combination with RPM to determine gear. ECT (Engine Coolant Temp) and IAT (Intake Air Temperature) can be nice, too, but I haven't found them to be very critical except for long term trending.

Logging is important because it allows you to carefully view things after your run in safety because you don't have to worry about keeping the car on the road while you analyze the data. Keep your logs in an organized manner so you can refer back to them later when you have questions about how your motor is running. Comparing results you think may have changed to your old logs can be very helpful when trying to track problems down. I name files by date and even keep a small text file with information about each of them.

Accurate instruments are important. Bad data is sometimes worse than no data at all. Does spending $50 or $100 less on a wbo2 make sense if its inaccuracy causes you to burn your motor down? That $100 is going to look pretty cheap when you have to pay for a new engine. You often get what you pay for. Don't short-change yourself in the area of instrumentation; it’s important.


Make Your Maps Smooth

This tip is somewhat subjective. I'm not talking about turning your maps into a perfectly linear slope. Good maps often won't even come close to linear. Making your maps smooth means they shouldn't have sharp transitions in opposing directions or contain individual cells that are dramatically different than neighboring cells. You can use a good base tune’s shape as a guide for your new tune if enough of the engine specifications are the same.

If you watch things in nature they rarely behave in sharp transitional ways. For example, when you increase the pressure of water in a garden hose, it doesn't shoot out of the end of the hose a short distance for a while and then all of a sudden increase three-fold. Instead, it shoots out of the hose an increasing distance in proportion to the increase in pressure. The rate at which pressure and distance relate may change, but even that is in a relatively smooth fashion.

Your engine is just one big collection of natural forces and interactions. As you make changes to fuel and timing maps, make small adjustments and ensure that they transition relatively smoothly with surrounding cells. Since the ECU is almost always reading data from multiple cells at once, you will make your life more difficult if you make large changes from cell to cell because understanding how much weight the ECU is placing on your change is very difficult to estimate in real-time.


Find a Good Place to Tune

Finding a good place to tune can make your job safer and easier. I'm lucky in that I have a highway very close that I can hop on and off easily. I have created a route of mostly right turns so I don't have to wait for traffic lights a lot. Your route should be quick, easy, and as safe as possible. Including areas in your route that allow you to safely pull over and inspect data and make adjustments is nice, too.

Although surface streets can work okay for low RPM tuning, they aren't a good place to conduct WOT runs. They're often bumpy, narrow, have too many cars, and too many pedestrians. The low speed limit is very limiting, too. Shooting past the speed limit, while watching a bunch of gauges, is a sure way to put yourself and others in grave danger. There are reasons for speed limits. The cost of your tune can never be measured if you seriously injure someone while making it.

Pick a spot with low traffic and good visibility. Gradual hills can be useful to help load your engine as you tune, but make sure you can see what's ahead of you without too much trouble. Picking a good time of day can change these factors, too. I often tune late at night because traffic is low and pedestrians are scarce. The air is also cooler, which I like, and no one can see the ear protection det can I'm wearing. The downside to tuning at night is that visibility is poor.

A lonely country road might be a good place to tune. Just be sure that you have a plan in case your car won’t get you home after your tuning session is over. 

Another helpful thing to do is to take a friend who knows a little about cars with you to drive while you tune. Be sure they know when to get off the gas and can follow your directions well. Then have them drive to your specification while you focus on the data and tuning. The result is more concentration on the road by the driver and more concentration on the data by the tuner simultaneously instead of trying to multitask by doing it all alone.


More Tuning

These tips will help you get started. I plan add a couple of example tuning sessions next that should spell out more detail. It’s not a complete guide by any means. I’ve still got lots to learn and my car’s tune is not complete.

Most of this stuff is common sense and a summary of the things that you can find in many different places on this site. Hopefully it will help newbies get the big picture sooner.

Updated the section titled 'Why Run "P30" Code on a "P28" ECU?' with a link to datalogging howto info. There are several good links within that thread, too.

It's been a while since I posted. I've been working on a few things like an electronic boost controller, a few PCV mods to try and reduce oil leaks and detonation, a few more tools to tune with, and a new engine with fresh everything and stronger internals.

My current engine is dying a slow death and leaks oil like nobody's business. I know it's burning some oil through the valve train - especially cylinder #1. I'm pretty sure I have a few seals that are on their way out. The rings seem to be good, though.

My car emits a little black smoke under boost. I'm not sure whether it's extra fuel, oil from pressurized crank case getting into the combustion chamber, leaky turbo seals, or what. I don't think it's the turbo seals, although I need to check for that again. The smoke may be partially due to the PCV system that was only partially modified for FI. I'm hoping it might just be too much fuel under boost.

A local tuner told me to run much richer than I've heard anyone else suggest or read anywhere due to the ethanol they put in the fuel here. I tried adding more fuel to "stay safe" like he said and I'm not convinced it's helping anything except global warming. I was running as rich as 10.8:1 under boost. I cut things back to 11.8:1 and the car seems to run smoother. I haven't had someone trail me to see if the smoke is gone under boost yet.

The car only smokes under boost - especially when I let off the throttle at the end. Since the AFRs get richer when you let off the throttle and things are so rich, I'm thinking there's a good chance much of the black smoke is extra fuel. If the smoke is proportional to AFRs, then it's a good indication fuel is causing the little cloud. Although my oil level is dropping fairly quickly I think it has more to do with the mess under my oil pan. The main seals and probably oil pan gasket are leaking like crazy. An over-pressurized crankcase due to partially stock PCV only helps to exacerbate oil leaks like these. All these things give me hope that the black smoke is not caused by oil, but just by extra fuel. I'm going to recheck when it's light again now that I've tuned the extra fuel out tonight.

Wish me luck.

BTW - I've been running more boost. I tried a couple of 10PSI pulls and WOW what a difference.

I slowly worked my way up through the fuel map by increasing the EBC duty cycle pull after pull until I had my maps tuned for up to 10PSI. I can't go much higher than that, without snapping a rod on my current engine, or overboosting the stock MAP sensor, even if I can keep detonation out of the picture. 10PSIG is ~8PSIA at this altitude, so there's still some margin of safety on the stock MAP at that boost level.

I'm probably riding the ragged edge at 10PSI on this tired old motor with the turbo I have, but it's only got to last a couple more weeks. Although I really don't want to blow this motor, it wouldn't be the end of the world if it popped. I usually set the boost to about 8 PSI for a lot of fun.

The new motor should handle 15PSI and will have more displacement. I'm hoping to eventually put down 300WHP and change on pump gas.

Quick Crome Tuning HOWTO

In preparation for more Street Tuning HOWTO, I thought it would be useful to explain a little bit about Crome Pro and how to tune with it. Keep in mind that I’m not an expert and everything I am going to write is my experience and opinion. So far as I can tell, there isn’t any official documentation for Crome, so much of my understanding is the result of guess-work, heuristics, and probably a little hubris.

When you purchase a Crome Pro license, what you are buying is the datalogging capability, autotune, and some other things. If you check the “settings” dialog, via File->Settings, after registering your copy you will notice four new tabs. They are called “Tuner Comm”, “Tuner Logging”, “Tuner”, and “DynoTools”. You will also have some new icons on your toolbar to access four different tables. The tables are “Target Lambda”, “Lambda Readings”, “Lambda Differential”, and “Knock Sensor Recordings”.

You will have to configure the “Tuner Comm”, and “Tuner Logging” tabs before datalogging will work. It should be pretty straight-forward. I won’t discuss it here. Do a search or check out the Crome forum for more information.

What are the “Target Lambda” tables? They are pair of tables that can be accessed with the low and high fuel cam buttons that are used as a reference in Crome (the software running on the PC) during tuning and autotuning. Set these tables to what you would “like” your AFR values to read in each cell. I don’t think the target lambda values are communicated to the ECU and don’t have anything to do with open or closed loop operation. You cannot change the amount of fuel your ECU supplies the engine with these tables. They are only used by the software on the PC when analyzing the data in the “Lambda Readings” tables.

The “Lambda Readings” tables are a pair of tables that eventually contain AFR information from the engine as it runs. It gets this information through a serial port connected to the CN2 connector on the ECU using an open protocol that Crome’s author created. I’ll include more on this pair of tables later.

The “Lambda Differential” tables are calculated based on the “Lambda Target” and “Lambda Readings” tables and are an indication to the user how much fuel should be added or removed before the engine is running as indicated in the “Lambda Target” tables. The differential values tell you how close to your ideal AFR value the engine is running in each cell. Provided the lambda targets are set for a proper tune, having close to 0 in each of the differential cells means your tune is complete.

The “Knock Sensor Recordings” may not be used on your ECU. I’m using a P28, for example, so I don’t know what this table would look like. My guess is that it would indicated when and if your engine was experiencing detonation. This sounds like useful information, but not all ECUs or engines are equipped to record this data. I advocate the use of a good det can when you tune, regardless of whether your Honda engine and ECU are equipped to give you knock sensor recordings.


Datalogging

When “Live Tuning” is enabled as the engine runs, engine vitals are displayed on the far right of the Crome application view. Things such as Engine Speed, Vehicle Speed, Gear, Manifold Pressure, Boost, Throttle Position, AFR, and quite a few other pieces of information are displayed in real time. One of the most important things about Crome datalogging is the AFR data that gets recorded. The manner in which this data is recorded is one of the most powerful things about Crome Pro.

You will notice that the four new sets of tables that become viewable once the features of Crome Pro are unlocked are comprised of the same number of rows and columns as the low and high cam fuel and timing maps. The row and columns of these tables correlate 1:1 with the RPM and MAP settings of the fuel and timing tables. This is a significant point.

Crome reads AFR values from ECU along with other information about the engine many times per second and uses this information as it records and interprets AFR values. It records each AFR reading relative to where the ECU is currently getting fuel and timing instruction from the low and high cam fuel and timing maps.

If you watch Crome Pro while it records, there is a highlighted cursor that “dances” around the table you’re currently viewing to show you where the ECU is pulling fuel and timing information. The cursor is always at the intersection of the engine RPM and MAP readings. Not only does Crome Pro use the cursor to record AFR data in the right row and column, but it will also record data in the low or high cam map depending upon if VTEC is engaged or not.

In short, Crome Pro records AFR data from the o2 sensor and correlates it to the instructions you’ve given the ECU with the low and high cam fuel and timing maps. It takes readings many times a second and then uses statistical analysis to give you an indication what the engine is doing for any given set of data.

You’ll notice that some readings in the Crome Pro datalogging window may be surrounded with braces. This means you need more readings in that cell before the displayed value should be trusted. The more data you have in a column, there more you can trust the value displayed there. Cells do not fill with data until you run the engine in that cell for a while.


The Tuner’s Job

Your job as a tuner is to fill as many cells with as many data points as possible to get an accurate picture of how your engine is behaving. This will enable you to make changes that improve the tune. Crome cannot control your engine speed, loading, or anything of that nature. It can only record what the ECU is doing at any moment in time. It is up to the tuner to manipulate the throttle, engine load, engine speed, and other parameters in a manner that will provide the best picture of how the engine operates at all times under all conditions. While doing this, the tuner must watch engine vitals to make sure conditions are always safe. Be careful!

The nice thing about using Crome Pro is that the data you log corresponds 1:1 with the inputs you set in the fuel and timing maps, so very little thought is required to determine what changes, if any, should be made. If you use Logworks or Freelog alone to datalog, you may have to make your own correlation before you know how to change the fuel and timing maps in Crome. For some people that may not be a big deal, for others it may cause a head-ache. In my opinion, having Crome Pro is well worth the money in saved head-ache and time.


Summary

That’s enough for this post. Understanding what your tools do is important. Once you understand what Crome Pro can do, you can create your strategy for safely changing your car’s tune in a meaningful way without damaging anything. Next time I’ll post more about the strategy I use.

Just updated the wbo2 sensor source information on page 3. Was able to get another sensor for a little under $55 from my local Autozone with a 1yr warranty. Getting ready to tune my new motor.

I did my motor swap a couple of weeks ago, but haven't had much time to tune it. Still running around town without VTEC to break in the motor. The motor rebuild consisted of:

Darton Sleeves. Bored out to about 1700+ mL
J&E custom forged pistons
Crower rods
Ported head
Crower springs
SS oversized valves and 3 angle valve job

I cleaned and painted things up, replaced all the coolant hoses, a fuel line or two, new belts, etc. It was a lot of work, but seems worth the effort. I'm still breaking in the motor, but it's definitely stronger than the old one. I'm excited to turn VTEC back on again and will connect my boost controller back up after it's broke in. I'm shooting for 300 WHP.

I've been having problems with E8 codes on my LC1 wbo2. Specifically, during hard deceleration it would crap out and I'd have to restart the car to get things back again. I purchased one of the HBX bung extender/heat sink units and things seem to be fixed. I made one trip with it last night and it didn't quit once. Someone suggested I try the HBX a while ago and I was hesitant due to the price (~$80). If it continues to work it will be worth every penny.

I plan to update the thread again to give more detail on my tuning strategy. I had a pretty good tune with my old motor. One thing I had to do after the motor swap was increase the fueling for my new motor because the displacement is higher. Compression is also a little lower due to different piston specifications and the fact that the motor is new.

The most obvious change from new to old motor besides the extra power is that there's no oil on my shop floor anymore. I can drive more than 300 miles without having to put another quart of oil in. What a concept.

Hey, the thread is almost to 10,000 views. Pretty cool. I appreciate all the help from everyone and hope that the compilation of things here in one place along with some wordy padding has helped a few people. Cheers!

Adjusting Fuel for Larger Displacement

My new motor was bored out for a few extra WHP (Wheel Horsepower). A bigger motor needs more fuel than a smaller one, since it draws in more air on every intake cycle. I was able to bore this motor out more than a stock one because of the Darton sleeves.

To verify my understanding I decided to fire the motor up without adding any extra fuel and see if it idled lean. I figured the change in displacement would be close enough for it to start up and idling it for a couple of minutes wasn't going to hurt anything. You definitely wouldn't want to run the motor under load in this state, since it would be lean and detonate. Sure enough, the motor idled lean.

I adjusted the fuel multiplier by using an original displacement of 1595cc and a new displacement of 1797cc. The fuel multiplier can be accessed via the Tools->Fuel Multiplier menu or by pressing CTRL-F. Crome responded to the fuel multiplier dialog changes by increasing the amount of fuel delivered in every part of the map (both high and low) to accommodate for the change in displacement. The numbers in the fuel maps don't change, but the injector duty cycle associated with those numbers does, if that makes sense.

After adjusting the fuel multiplier, the engine was running richer - a little too rich in fact. Although I could have manually tuned the extra fuel out at this point by adjusting every cell in each fuel map, I decided to get closer to the mark with a different fuel multiplier first so I would have less work to do fine-tuning my maps. Instead of 1797cc as a new displacement, I iteratively backed out the old changes and used new values of 1700cc, 1750cc, 1725cc, etc, until I had target AFR values that seemed close to what I wanted. Choosing values that are half way between two known quantities until the desired result is achieved is called a binary search and is a quick and safe way to work. My final fuel multiplier left things a little on the rich side to keep the tune safe. You always want to tune from rich to lean.

A simple lesson can be learned from this experience: merely adjusting the fuel multiplier by entering your exact displacement change does *not* get you a good tune, no matter how good your initial tune was or how accurate your displacement change was. Subtle changes in the engine's characteristics mean that entering a displacement change will get you close, but not dead on. You need to tune the maps to make sure they are safe! I've seen a number of people who put way too much trust in their ROM editor.

I added a book to the resources section of my post titled "A Tuning Guide for Noobs / Tuning HOWTO". The book is Introduction to Internal Combustion Engines. I've had it for a while and it's really interesting.

Portions of the text are over my head, but most of the information is very useful and I just skip the portions that are really heavy. I don't remember enough Chemistry from High School or College. Oh well. I will go back to those sections if I feel it would be useful in the future. Right now I don't care how gasoline is made or the exact chemical reactions that occur during combustion, I need to know high level principles.

The chapters on Combustion of Fuels and Spark Ignition Engines are really interesting and have been helpful to understand how detonation works, for example. There is a lot of other useful information if you have any curiosity about Diesel engines, two strokes and other cool stuff. Knowledge is horsepower.

Tuning Fuel Maps via Crome

Modifying fuel maps via street tuning is a relatively easy thing to do if you have the right tools and some patience. Although you can tune timing on the street, it is more difficult and less precise than tuning timing on a dyno. While this post will focus on tuning fuel maps, you must be conscious of timing to prevent engine damage from incorrect timing. Simply having correct air fuel ratio will not always prevent detonation.

The tools that I highly recommend for tuning fuel maps are a wideband o2 sensor, a det can, and of course data logging. An EGT gauge might be nice too. The more information you have the better. Even with all these things your visibility into the engine is still pretty limited. Without a good understanding of how things function, it will be difficult to always make changes that will improve your tune.

One of the most important things to remember is to tune from rich to lean. Although very rich mixtures can cause detonation, lean mixtures are far more prone to cause detonation and engine damage. The better your base map, the quicker and safer your tune will be. A good base tune will be a little rich across the board so you only have to pull a little bit of fuel out in each cell of the map. You will likely have to pull differing amounts of fuel from each cell. Tuning fuel maps is all about obtaining the correct AFR in each cell by increasing or decreasing the “number” in each cell.

While you tune, you will need to watch AFR, and EGT closely to ensure you don’t operate your engine in a dangerous configuration. Listening to a det can to check for detonation is also important and could save you costly repairs. If you hear detonation, see lean AFRs, or see EGT rise sharply over a safe level you should let up on the throttle immediately and fix the problem. Sometimes this will be merely adding fuel, and sometimes it will be pulling timing out.

You should also regularly inspect your plugs to check for signs of detonation. Learn how to read your plugs. There are many resources on the Internet that can help you. Experience and practice will also help. To get the best read, you should cut the engine after a pull and coast to a stop, and then remove the plugs to inspect them. Be careful removing and installing plugs into a hot aluminum head. It is not recommended that you do this in many manuals because it is easy to damage threads this way. If your plugs show peppering or bits of aluminum then you know you need to listen harder for detonation.


Setting up

To set up for a tune you need to gather your equipment, find a relatively safe and convenient place to tune, and get your bin file ready to start tuning. Effectively tuning your engine involves isolating as many variables as possible to simplify interactions and make deciphering what your engine is doing as easy as possible.

Some things that will help isolate variables are disabling VTEC, disabling the stock o2 sensor, waiting until the engine has reached operating temperature before modifying fuel maps, always tuning with approximately the same outside temperature, tuning with the same electrical load, tuning at the same elevation, etc.

Disabling VTEC and the stock nbo2 will keep you from having to worry about the high cam fuel and timing maps, or the ECU going into closed loop mode. You can make these two changes in the options page of Crome. If the ECU goes into closed loop mode, it will use the nbo2 sensor value as feedback and add or subtract fuel on top of the values it reads from the fuel map, which will make it impossible to figure out if the changes you’re making are correct or not.

The ECU will add fuel when the engine is cold according to the ECT sensor readings. Running a cold engine hard is not a good idea and furthermore trying to tune or datalog while the ECT value is changing will be difficult since the ECU will change fueling in relation to the current reading. The same principles hold true with regard to IAT (intake air temperature). If you tune while it is very hot out one time and very cool out another, the IAT compensation of the ECU will make AFR values differ between sessions. The ELD sensor will change how your fueling works, too.

Changes in system voltage will effect how fast your injectors open and can have an effect on AFRs. The faster the injector opens, the longer it will be open before closing again for the same pulse width, manifold pressure, and other parameters. If you always tune with your headlights on, for example, you will have gone one step further to isolating as many variables as possible.

Things such as ECT compensation, IAT compensation, injector battery offset, and others will eventually have to be tuned, but you can get by without modifying them if you can keep them consistent during your tuning. You can tune them later by modifying each parameter one at a time and verifying that your tune remains consistent. Modifying each compensating factor to account for the environmental change until the tune remains consistent no matter how the environment changes will ensure a consistent, accurate, and safe tune.

I try to tune at about the same time every night. I use my headlights every time. I drive the same routes every time. I keep an account of each tuning session including temperature, time, any audible or visual observations, and all data logs from Crome and Logworks.

Many people initially wonder what gear they should tune in. Crome only records data during live tuning when the car is in gears 2, 3, or 4. I like to street tune in gears 2 and 3. The third gear would probably be easier to tune because changes in throttle result in relatively slow changes in RPM and speed, which makes controlling what cell the ECU is pulling data from much easier. Unfortunately third gear results in higher road speeds, which are more dangerous. Higher speed also poses constraints for the roads that you tune on. Getting a ticket or navigating around other cars while traveling quickly and watching a ton of gauges is not ideal or safe. Because of these difficulties, I end up tuning in second gear much of the time while street tuning. A third gear pull now and again helps a lot, but adds to the risk.


Crome Datalogging

Crome keeps track of what cell the ECU is pulling data from. It displays what the current cell is by highlighting it with a different color. This is called cell tracing. As you drive, Crome takes readings from the o2 sensor (you are using a wbo2 and not an nbo2, right?) and adjusts the representative value accordingly. Although I’m not sure what sort of statistical analysis Crome performs for each cell, it appears to provide and average of at least a subset of data collected for each one.

Crome determines in real-time whether or not to adjust the lambda reading value in each cell according to the current AFR according to a set of criteria. These criteria can be found in the Settings dialog by selecting the ‘Tuner Logging’ tab. You can get there via the File->Settings menu. You can set parameters to determine if Crome will “log” the current AFR based on throttle position, AFR, engine speed, engine load via the MAP sensor, water temp from the ECT, and current gear.

I once wondered why Crome wasn’t logging data anymore during a tuning session and realized that my car was slightly overheating. I also realized that my ECT compensation wasn’t set quite right because my AFRs became very rich. The ECT switch that turns the radiator fan on and off was faulty. I replaced it and saved my motor from a meltdown all because the Crome data logging feature quit working.


Making a Couple of Runs

You need to figure out how to get the ECU to operate in as many of the cells as possible to get a good tune. This doesn’t mean you should force it to read something it won’t naturally read, but if it can happen in a real world setting you had better have the cell set correctly to avoid problems.

Getting your ECU to read each cell involves manipulating the throttle and gear to achieve the right engine load and speed. Think of it kind of like a complicated etch-a-sketch. Sometimes I like to try and hold a certain speed and vary the engine load by feathering the throttle or sometimes stabbing the throttle to move the cell horizontally along the map. A higher gear helps with this strategy. Climbing a hill also works well for this strategy as the car will increase in speed more slowly and allow you to make horizontal changes of the current cell easier.

Another strategy is to keep the throttle relatively still in a certain column while the engine speed gradually increases to obtain AFR readings for the entire column. A lower gear will tend to make this strategy work easier. You’ll have to control the throttle in relatively small adjustments to keep the load as close to the column load as possible. Since the ECU averages values from surrounding cells and does not pull fuel and timing data from the current cell only, the closer you can keep the actual load to the value set for that column, the more strongly the AFR data in each cell will correspond to the column it is recorded in.

Often I use a combination of gathering rows and columns. Don’t be afraid to overlap areas of the map you’re working on. It doesn’t hurt to gather more data for a cell. More data only makes the value more accurate.

A couple of things worth noting are that cells surrounded in parenthesis indicate that not enough data has been gathered and that sometimes readings in certain cells may be the result of instructions from previous cells. Cells with AFR values noted within parenthesis mean that you only got a couple of AFR readings for that cell before the ECU started reading from another cell. Many times, the reading is not very accurate and you should try to move the current cell to that location and hold it there for a bit to get more accurate data.

Cells in the lambda readings table sometimes get filled during quick changes in engine speed and/or load. For example, often when I am slowing down after a hard pull I lift off the throttle and start slowing down. As I slow, the AFR becomes very rich for a moment and engine speed and load fall of rapidly. As the cell tracing flies across the map, it fills a few cells with rich AFR values. Since this behavior is rapid, the cells often indicate insufficient samples for accuracy by displaying AFR readings in parenthesis. Don’t trust these values or think that your tune is way too rich in those cells until you get a better sample set for that cell by holding the engine in that spot for a while.


A Tuning Paradigm

One of my favorite paradigms for overall tuning is to first verify that a section of the map is relatively safe, meaning the AFRs are rich and there is no detonation. I then drive for a while varying speed and load to get as many data points as possible in that section, tweak the fuel map to get AFRs closer to target values, save the log along with a description, clear the log, and reiterate.

Keep in mind I said that I tune a “range” of cells, and not necessarily the entire map. The range has to be realistic. You can’t start by tuning only the boost cells, for example, because you can’t feasibly keep the car in boost at all times. When you slow down, you’ll have to come out of boost. This means that ranges must be chosen in a logical order. Lower engine speed and load cells must be tuned first. Vacuum cells should be tuned before boost cells, and the low cam should be tuned before the high cam.

If your car won’t idle correctly, for example, it’s going to be difficult to tune your engine because it will be stalling every time you hit a red light. Tuning is like building a house in that you have to build the foundation first. Tune your low cells first and then move up. You’ll have to be disciplined to keep from pushing into regions that don’t make sense. Impatience leads to blown motors. Going slow on the tune will make your car eventually go fast.

As you log AFR values you will notice trends in the data. Sometimes an entire column is lean or rich of what you want. Sometimes an entire row needs adjusted. Sometimes the entire map or a region of the map needs adjusting. As your tune progresses, changes will consist of single cell modifications more frequently than not. Toggling between tables, 3D maps, and 2D maps will help you analyze the data and make correct changes. It may also be easier to select the range of cells you want using different views, so use all three to help you.

Remember to keep things rich to start with. If you observe a trend in logged data leading towards a lean AFR, you may want to fatten up cells that you haven’t visited yet to make sure you don’t cause problems when you move to that portion of the map or accidentally go there.


Target AFR Values

I like to use the target lambda, lambda readings, and lambda differential maps to help me determine if each cell needs to be fattened up or leaned out. If your target lambda values are set correctly, tuning your fuel maps is as easy as viewing percentages from the lambda differential map and adjusting the fuel map cells up and down to adjust the differential as close to zero as possible. I don’t worry about anything 2% and under.

Here’s where I remind you again that I am a noob, too, and that you must use this information at your own risk. Target lambda values are important and you’ll have to decide how you want to set them based on your specific setup and goals. Using incorrect target lambda values will mean wasting a lot of time on a bad tune at best, and damaging your engine at worst. Fuel economy and smooth power delivery can also be affected by the way you set target lambda values.

Target lambda values should be around 14.7:1 at idle and high vacuum and slowly richen towards low vacuum. AFRs should be around 11.8:1 to 12.2:1 during moderate boost. Like everything else in tuning, you should not plan to have any sharp changes in target lambda values. Make changes gradually and smoothly.

High boost should tend to be on the richer side of the boost target range, or even a little richer. You’ll have to decide how you want to set your fuel mixtures. Keep in mind that richer is safer but produces less power. Lean is dangerous, and really rich can even cause detonation. I’m attaching my lambda target values for your reference in Figure 1. Do not use this as the Holy Grail. You are responsible for your tune.

Keep in mind that no amount of extra fuel can keep your engine safe if your timing is way off. I suggest that you make your tune on the conservative side so that if you get a bad tank of gas, encounter high temperature air, or find some other part of your tune that is wrong you won’t burn your motor down.


Percentages

As you make changes to your fuel map, you won’t initially know how much of a difference they are going to make. The default configuration for Crome is to adjust fueling by 3% for every CTRL-up or CTRL-down change you make to the map. You can make finer modification by actually typing in the change via the keyboard. As you gain experience you will be able to hone in on a target lambda value much quicker. Make small changes when you are inexperienced to avoid overcompensating and leaning your motor out. Remember, go slow to go fast. Even if it takes you longer to tune your car it will be worth it if you don’t damage anything.


Different Software

You don’t have to use Crome Pro to tune. You can use Freelog to log AFRs and simply adjust fuel maps via Crome Free. You could also use Logworks on its own. If you can get engine speed and load data into Logworks you can use the View->New Chart menu item to produce a view similar to the lambda readings map in Crome Pro. Feel free to use the tools that you choose. They all work in a similar manner, but may differ in ease of use according to your style.


Tuning Timing

Even though we haven’t addressed tuning timing in this post, it is very important. Tuning timing must be considered if you cannot prevent detonation in certain parts of the map by fueling changes alone. Tuning timing on the street is much more difficult than tuning fuel. With the right tools you can obtain a relatively safe tune with a lot of patience. I’ll write some of my experiences in following posts regarding timing. It’s given me a lot of grief and I think I’ve finally made some progress in that area.


Finishing Up

Don’t be afraid to spend a lot of time tuning your car. I have been playing with mine for about a year now and have logged over 100 sessions complete with observations, a log of changes to the motor and setup and have learned a lot. I still have lots to learn.

One you have the low cam tuned properly, you can enable the high cam at a low engine speed and tune it using the same principles listed above. If you have made a lot of changes to your low cam fueling, you’ll want to be careful that your high cam fuel map isn’t grossly off before you start diving into blindly datalogging on the high cam. Once you have tuned the high cam so that VTEC switches over without affecting AFR much and everything is safe and smooth, you can set your VTEC engagement RPM back to stock. The best way to set VTEC engagement is to dyno low cam and high cam torque and then set it for the intersection of the two.

Good luck – go slow, isolate variables one at a time, conduct experiments, try to guess how changes will effect the tune before you make them, change things slowly and try to have fun. It will take a long time, but you will learn a lot.