I was wondering what vacuum using / related systems are activated / deactivated at wide open throttle. I still have not tracked down my hesitation / backfiring (through throttle body) problem and I'm desperate to find out why my car is acting so stragely.

Here's what I've tried: (thought it was fuel delivery problems) fuel pump k fuel lines k fuel filter:replaced injectors:havn't tested them air filter:replaced (thought it was electrical) TPS:replaced $MAF:replaced$ EGR:replaced Oxy on exhaust:replaced.

Now I'm under the impression that it might be vacuum related. I've fixed a couple of leaks, but it does no good.

One last thought: could the relay on the TPS be bad? It's an intermitent thing, and I've found no pattern other than: if you accellerate VERY slowly, it never has problems. About half the time if you accelerate normally, it will BF through the TB and the other half of the time it's fine. Regardless of either of these two conditions, it never does it near WOT, but It acts like it's got a rev limiter on it, until I hit WOT then VROOOOMMMM it's just fine!

Please Help!!

 

EGR is disabled at WOT. Not much else happens with the vacuum system. Just out of idle curiosity, if you have your heater on, and the fan at full blast, do your vents switch to the defroster at WOT? (this would indicate that you still have a vacuum leak somewhere......)

However, It does sound to me like the TPS is going. How many miles do you have on the engine? How long has the problem been going on? Do you have a scanner that you can watch TPS voltage when the problem occurs?

Have fun now.....

 

What the heck? every time I type ok I get a smiley... anyway.. OH! it's because of the colon Got it.

Don't have a "scanner" other than the one on my computer! Where might I find this scanner of which you speak?

Also, I've never tried the heater thing. I'll try at lunch or when I go home tonight.


Is there a way I can disable the EGR temporarily to see if that's my problem. (I guess I could just remove the lines and plug them?)

Thanks for the help, I've been pulling my hair out. It's really my wife's car (damn chevy lovers) and I really would rather not mess with it, except the handling is outrageous. and for a v6 I've never felt such pull at WOT. If we buy her a new car, I just might transplant it into my Triumph. (assuming I can get it to run)

I've thought that the ECM might be bad too, so if I've exhausted all possibilities, I will hunt one down and replace it temporarily to see if that's it. If not, back to the store!

Thanks again!

Oops, forgot to tell you about the car: It's a 2.8L V6 MPFI (1985) with about 115,000 miles on it. Close to rebuild time I've heard. It's a daily driver and we'll probably trade / sell / cannabolize it when we get a new car. (family time is soon, can't justify a sports car for transportation... for fun: that's annother deal!) The IROC-C thing is kind of a joke. The dealer that sold the car put the IROC sticker on it and then put the -c on it when customers freaked out about it having a 6-cyl! So he made up some story about it being an IROC-Z with a V-6 instead of a V-8. Not even close, of course!

[This message has been edited by 85IROC-C (edited December 06, 2001).]