Where do you start when tuning a chip? Update 10/24/2011

I have read a lot of articles on tuning, conversions and engine swaps but no real guidelines? We have a bunch of stickies here and links to other stickies with tons of information. Technology in the automotive world is going through the roof and so many different systems so maybe we can come up with a list.

I know what I do first when tuning a vehicle, or doing a carb to EFI conversion or late model engine swap.... I usually burn a chip that is as close to the motor as possible. Like 5.7L auto chip for same cubic inch engine with Auto, or 5.0L manual chip for same cubic inch manual trans. There are a lot of differences in a chip, some you can not see but will make a difference in vehicle drivablity. If you know it does not have EGR etc... disable that function and associated error code.

OK now what do I need to know before tuning or recording data to tune?

1. Is it running?
2. is it running correctly? Can't tune a motor with one cylinder with low compression or a vacuum leak.
3. Are there any error codes stored?
4. Battery in good shape?
5. Charging system properly working?
6. Fuel Pressure?
7. Tune up items like plugs cap rotor wires air filter all new or recent and known good.
8. Fuel filter new!
9. Fuel fresh?

Those kind of things I need to do before I would ever change a thing in tune or it's a waste of time. One thing that made it a little easier for me was the purchase of a good Scan tool. Not just computer software for the enthusiast but a real scan tool. Mine is an Tech Scan Auto Xray 7000 that was about $300. but this is a tool that started with information from the car manufactures as mandated by law so mechanics could read their computer. Not something that has been hacked or reverse engineered. It also has a cable to hook to a computer for yearly updates, it will also datalog.

I started with an old laptop and WinALDL. That may be a common story. But so many things have changed in 10 years I remember reading about learning hex and dex and base 10... thank God for Mark at TunerPro!!! :wtg:

So anyway that is usually the first thing I do is use the scan tool to check most of the things I listed above. If you don't have a ScanTool just use your laptop with whatever software you have.

From there I know if I have to turn off error codes for systems no longer on vehicle I forgot about originally, if a hot rod or EFI conversion. Like EGR, Charcoal canister, Air diverter etc... depending on system you are using.

Then on to data logging to get fuel correct. This is another huge topic and adjusted different ways by different tuners. So I am not going to get into it here, but there is a couple tips I will pass on. First disable PE, this way you can log more BLM cells with data without it being effected by extra fuel from PE. Disable Highway Lean Cruise if it is on as this will ruin BLM data. I leave AE alone because it will be there afterwards anyway, when I have tried to data log without AE it drove so bad all I got was bad BLM data. Now that is done engine needs to be totally warmed up, then start to log your BLM data!

Remember getting the Main VE table fueling correct is first thing that needs to be done because all other things are based on adjustments from this setting being correct!

1. Find a wide open road with little traffic. record data from stop to 80 MPH or as high as it will go at 10% throttle, you can see TPS% in any data logging software. Then same thing at 20%, 30%, 40% all the way up to 100% WOT. If you spend the time to do this you will have all possible cells filled with BLM data to make your adjustments to VE tables.

DISCLAIMER: You can blow up or melt a motor if information below is not done properly, use at your own risk.

Then on to adding or subtracting spark depending on engine. I like to use a knock sensor and if I see knock I take out timing at that RPM and MAP cell. If I don't see knock I add timing in that RPM and MAP cell. When I have bumped into knock across the board I usually take out 2 degrees from everything except idle which I tune separately. If you want all the spark advance you can get and all power you can get use premium fuel which nowadays is usually 92-93 octane. If you used fresh premium to tune WOT and always use premium you can leave WOT spark as is. I would still back out a couple degrees from everything else, except idle again, tune separately. This of course can still change do to weather. If you tuned spark this way on a cool humid day it will be fine on a hot dry day. Weather does effect timing.

You have seen things that give you ability to change tunes from economy to power ETC? Well if you tune your chip right you have all this by controlling your foot. I tune for idle, driving which is the widest range, then WOT. Then you have it all.

I have done some fuel mileage testing on highway and by tuning this way and using the HiWay lean Cruise on 7747 the gains in MPG do offset cost and add savings of premium fuel. Other newer PCM are same results. Mileage around town does not. This is do to EFI ability to control spark timing and uses the knock sensor for test on how much to add. It will notice difference in 87 or 93 octane. If it were an old carburetor car you would have to add high test fuel, then add like 4 degrees timing or so, then keep your foot out of WOT to get same results. EFI is a good thing!

So what says you? Where do you start? If you'd like to add to this starting point feel free to add information below.

HTH! :rockon:

For more information check out this thread:
http://www.gearhead-efi.com/Fuel-Inj...odified-engine.