OK guys I am wondering if someone can give a little training write up on tuning. Like explain the processes and all the formulas and such. This would help a lot for guys looking to get into self tuning.

 

There is lots of info if you look in the Computer Diagnostics and Programming forum.

 

Moving...........

 

If you google for LT1 PCM tuning you will find several useful pages describing tuning for beginners.

 

and the free download from tunercats has a help file that is awsome,i assume you have a 94?any info in your sig would help.
just get the trial version and buy a deff file,$ee i believe, but check on there website.the trial version is 30 days and starts from the time you install the program, so read up on how to use it, then download it and buy the deff file,$20, for your car and tune away.it would help if i could post it for everyone interested to get used to the program before starting there free trial.if you know what your looking at first, the 30 day trial will be that much more helpfull.

 

here we go!
Tuning the OBDI LT1 Engine
Part of the fun of owning a computer-controlled, fuel-injected sports car, is being able to tune it! What a dream, to be able to change the fuel and spark curves, change your idle, remove annoyances (C.A.G.S "skip-shift"), etc.

Below I've posted some of the PCM images I've tuned for my '95 Z28 over the months, using TunerCat. TunerCat is an awesome program, also known as Computer Automotive Tuning Systems (C.A.T.S.), which allows the above things to be done You'll also need an additional PCM file ($EE for the '94-'95 F-Body LT1; $DA(3) for the '93 F-Body LT1), which will cost you an additional$19.95. from tunercats
Secondly, you'll need the appropriate cable connector to go from your car to a computer. These can be bought from AKM Electronics for a reasonable price. Of course, you'll also need a computer to run the program on! A Laptop is ideal, but not necessary if you can put a desktop & monitor close to your car's parking spot.
There is no VIN or individual PCM restriction, so you can tune multiple cars and/or PCMs without having to pay any additional fees, compared to LT1_Edit, which is more for the base program ($200), optional scanner ($50), and each additional PCM ($50 or so). However, there is currently no definition file for OBDII cars ('96, '97), so you will only be able to tune '93-'95s.
The Basics
When tuning an LT1 PCM, one of the first things to do is remove the basic annoyances, such as CAGS (skip-shift), and change the fan settings to keep the car running cooler. You should also change the cylinder size if you have over-bored your engine.
If you're changed your fuel injectors to a larger size, now is the time to change them as well. If you are using the Ford/SVO/Bosch style, you'll want to multiply their rating by 1.056 (24#=25.34, 30#=31.68, 36#=38.02, 42#=44.35, etc.), to accomodate the lower fuel psi rating at which they operate (Ford's 39 vs. GM's 43.5).
You should begin by adding about 2° of spark advance across the two tables, to get more power out of your combustion. Monitor this increase with a scanner and make sure you aren't getting any consistent knock retard. If you are, note in which RPM range it is, and at what MAP value, and take 1° or 2° out of the appropriate cell. You can pretty much add advance until you get spark retard, and then back it off some. This will generally produce the cleanest combustion and best throttle response. However, sometimes you can have too much timing without knock, and the best way to fine-tune timing is on the dyno.
Now you should log the car, while driving with all ranges of acceleration, from 800RPM all the way up to around 4000RPM. You want all different amounts of load on the car at the different RPM ranges to get the best data possible. The following will allow you to get the car running close to 14.7:1 when you're not at WOT, giving the best overall gas mileage and lowest overall smog output. After logging for about 10 or 15 minutes:
· If you are using speed density mode (no MAF sensor), run the log through VEmaster (search the web). Repeat until your long term BLMs are near 128.
· If you are using a MAF sensor, then find where your logs show a BLM of < 126 or > 130. Note what the airflow number is at that point, and then go to that entry in the respective MAFS table in TunerCat. If the BLM was < 128 you will want to make the MAF frequency number lower. If it was > 128 you'll want to make it higher. The best way to modify the number is to multiply by %. Start with 1.025-1.05 or so, relog and see how the BLMs are affected at that airflow point. Repeat until the long terms are close 128.
Tuning Wide-Open Throttle (WOT)
Once your normal driving is fine-tuned, giving BLMs of near 128 (126-130), with no knock retard, you can move on to removing fuel from the WOT (PE, i.e., Power Enrichment) tables, shooting for an AFR of around 12.6-13.4--TunerCat's help file will show you how to make the tables do this. You should also increase the Open Loop AFR table entries by about 3 or 4 across the board. This will make the car run leaner before going into open loop, helping increase gas mileage.
You will also want to tweak the spark advance values at the 95 and 100 MAP settings. Too much advance can not only cause spark retard (and damage to your motor), but can be needless for producing the most power. However, too little advance can severely reduce the potential output of your engine's combo.
Now that you've done a good amount tuning, you are ready to take the car to a dyno for more intensive power increase. Raise and lower the WOT tables until you make the most power without getting any knock.
Now you have a car that is custom tuned, all by yourself!

 

note: not writen by me, but ill make another post. i wish ihad read this 10 times before trying tunnercats.my 30 day trial version was wasted trying to understand my last post.

 

That's a nice, concise writeup. Thanks 11secgen.

 

I am brand new to this. Just bought a 95 z28 which came with a laptop and tunercat. The prior owner had tuned it well and I don't need to change much. My ? is: can I make a program to reduce HP, acceleration, etc.. to load in when my teenager drives it? I did one program where I turned on the Traction Control and reduced the fuel flow- my only attempt at using the program. I realize this is the opposite goal most of you have but I wonder how much I can de-tune it and how to go about it. There are a lot of other parameters in there I don't understand. Is there a comprehensive instruction tutorial? Will I mess up my engine fiddling with stuff I don't understand?
After seeing some of your problems with loading programs and messing up the computer in the car, I am trepidatious about doing this very often . My one-time attempt worked OK. As far as I know the previous owner had no problems with the current setup.

 

move your rev and speed limits down to an annoyingly low number.. haha

 

Lmao that would suck. getting on the highway hitting rev limiter at like 3500. owned!

 

I just happened to see this as a link. I wrote the snippet that 11secgen posted, way back in 2000 or so. That website is down now, but I've since created a new tuning website with more up-to-date and thorough (and free) information.