i drive a 97 z24 cavalier...i know its a cavalier....but it has a T04e turbo and 273hp to the wheels. well the thing is here sometimes it runs good and sometimes it runs like crap because the computer goes into limp mode and retards the timing and the car is literally shooting flames out the back....i took it to south florida performance and they said they dont know? does anyone know of anywhere that either does custom ecu reprogramming or anyone have any good ideas? please dont tell me to sell it! thanks  

Nah, we aint like that round here. Anything is welcome. We are also fans of the J-body, so you're alright here, as long as ricer attitudes are left at the door.

Ok here are alot of questions, but answering them will help us help you. What makes you think it's the computer? Who timed that car? Is it the factory computer and if so has it been reflashed? That may sound stupid, but humor me. Is it aftermarket, and if so what company made it? Are you using piggy back controllers like Apex'i S-AFC? Does the computer mess up at certain times, maybe when you drive a ceratin way, or for a certain time? Flames out the back? That's very strange, how high are you revving this car? Even an out of tune car shouldn't really do this.

Give us a list of your mods, but be thorough. Link to pics if you can (just for viewing pleasure, we love seeing tuned cars that are out of the ordinary). Most everything is fixable in someway, so selling it is pretty far out at this point.

And welcome, btw.  

what could be retarding the timimg besides the computer... cant time it..it times itself! its a factory stock ecu...it has a piggyback s-afcII handling the fuel mapping. its basically whenever i get on the throttle...but usually when its either cool out or the car hasnt been running for a while runs well...but thats what makes it really wierd. the owner of SFP said it goes into a limp mode. but he doenst know why? oh yea the flames....lol.... its because the timing retards itself so far that i guess the gas is not even burning and just flames out the back. the car never goes past the redline for two reasons...i dont beat the car and it has a rev limiter.
Mods:xs power t04e 57 trim turbo
apex custom 2.5" turbo back exhaust
greddy type s blow off s-afc II
custom 2.5" charge pipes(custom as in ghetto)
top mount 99 gst intercooler
all types of garbage but all for go and none for show.
-Khody-  

take a look at a couple of things, your ignition system, is it working right, your map sensor and i think they have one. also check your fuel pressure and volume, what size injectors are you using? how are you controlling timing, usually on boosted cars you want to retard timing as boost increases at least 2 degrees per psi.  

Well, you're right about the flames. When the ignition retards and the fuel that hasn't been burned hits the hot turbine, it goes kaboom. I read about an anti-lag system working like that. The little explosion INSTANTLY spools the turbo, but it can cause some damage after a while. You might want to check your turbo for damage when you get this problem fixed.
Anyway, maybe the car is just knocking a lot. There was an article in this month's Turbo Magazine about tuning factory ECU's. They were using an EVO and they said that on that car the ECU will go into a "safe mode", which significantly reduces power. It happens when the engine gets too hot, or starts knocking. I'm guessing that your car is doing the same thing, but since the EVO's safe mode is tuned to work with a turbo, and yours isn't, it's causing major problems. I would buy a knock sensor and take it to a dyno.  

thanks but on my car i dont have a knock sensor....but i am running a small gst intercooler and sometimes gets really hot.....thats helps a little.....because the car ususally runs better in the cooler weather.  

Maybe all you need is a front-mount. Spearco has some cheap ones.  

I don't like rice.. on ANY car. Performance parts on any car are alright and will get my props..

as for your problem.. I agree, heat is probably the issue.  

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what could be retarding the timimg besides the computer... cant time it..it times itself!

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I just don't know.  It really sounds like knock sensor to me.  Are you sure your car does not have a knock sensor?  The cavaliers came with one.  Brings it back to "who installed the equipment?"  Check the fuel maps in the piggy back also.  My Previa used to go into safe mode because of oxygen sensor voltages getting to high.  It wasn't as extreme as yours though.

Trying to think, does that thing still have a MAF meter?  If it does, that could be a major problem.  Also, there is a intake inlet air temprature sensor.  If the inlt air gets too hot, wham!, saftey mode.  The only way to fix that problem is to mount it before the turbo.  It has to have a reading, it changes fuel mapping and timing for the winter or when it is really hot.  That seems to be the problem to me.

I'll call my cavalier nut friend tonight and see what he says.

Dave-  

OK, I IM'd him and asked what it might be.  He said it was most likely the air inlet temperature sensor.  The higher inlet temperatures from the turbo will cause the problem you are explaining.  Try that, I hope it works for you.  I hate seeing these "ghost" problems in tuned cars.  Good luck.

Dave-  

Wow Big. Nice job. 5 Cheezy Stars for you.  

ur gay! thanks for the comment...really helped?  

So, who is gay?  If you don't want any help, or if you are going to be a smart @ss, I think you found the wrong board to start posting on.  We were both just trying to help a fellow tuner in disstress.

Have a happy new year and I hope your problem gets fixed.

By the way, a decent intercooler could also fix the problem.  In my opinion, it is one of the most important parts in any forced induction system.  At least any that you want to get any power out of and keep reliability.