My car's a Tuning Nightmare!

[Black1987Stang]

Ok so my car is a tuning Nightmare.....I'm using a Tweecer R/t but it would still do it with a stock computer....If someone can help I'll be Greatly Appreciated....This is the deal....I have one knob position for a bone stock tune, nothing is changed except for loading the PRO M 24 file into it for my maf to work right.....The other tune is the same as that but is ran in open loop and has a few tweaks to the maf transfer (a little richer on the bottom end)....I can start it and it will be fine for a couple minutes then it will go PIG RICH or sometimes CRAZY LEAN out of Nowhere ......Rich as in 10 to 1 and Lean as in 20 to 1..(I have a wideband)...If I switch it to the other tune it will be fine, and eventually it will go Real rich or lean again so I have to switch to the other tune.... I'm really lost....I'm really getting the hang of tuning but it doesn't matter if the tune all of a sudden goes out of whack. I swapped the computer and maf out for my friends so I know they're not the problem. Last time I checked the ECT was working fine also...When it is really rich or lean if I go WOT it will clear up but will go back once I let off the gas.

 

[big frank]

You may know some of this, but I'll mention it anyway...

When you are on your basically stock tune, and you start the car, it will be in open loop for about 45 seconds untill the O2's heat up. then the car will go into closed loop. During the time it is in OL, your wideband will be all over the place, but usually int he lean area.

When you switch to you other tune that is OL all the time, the O2's aren't being used at all. The EEC has a much harder time trying to stay stoich (14.7afr) and will hunt around more, especially at idle. And since it's using the OL fuel tables all the time, you may need to adjust them to stay at 14.7, which is what your computer will be trying to do for you.

Are you using Binary Editor and EEC Analyzer? if not, you should be. It will help you tune in your MAF and spark much easier than guessing at it. I believe you said you had a R/T so you can data log and use the logs EEC Analyzer to get it all tuned in.

Other things to check...

CID setting for your engine size.

Injector slopes and offsets

You might want to post up at eectuning.org where you can get some other information using the TwEECer and EA and BE.