Heat related problem...

[FormulaSlickG94]

Could an opti that's going bad go koo koo when it's really hot outside? My car acts totally normal when I am driving in cool weather but as soon as it hits 80 and up outside I"m in trouble. If I'm at a stoplight after driving for awhile the car will rev itself up and I will have to hit the brakes harder to stop it from jumping off on me (It keeps fluctuating between 500 and 1000 rpms) When that starts happening and I hit the gas the car begins to bog and stop accelerating much like the first time my opti went bad about 25,000 miles ago when I had it replaced. I did have a starting problem but the fuel pump took care of that.

What are some things that could cause the car to bog and rev itself when it's real hot? I think I've pretty much ruled fuel problem out of the question.

[Injuneer]

Something doesn't like the excessive heat - probably an electronic device. ICM module, Opti optical module, alternator voltage regulator and fuel injectors are a few items that come to mind.

Heat can also increase the electrical loads, and make a poor ground connection a problem, particularly those for the engine and the PCM. What does the volt meter show when this is happening?

[paxton350]

hmm

i had a similiar issue with my w-body a while back- it was due to an aftermarket prom i had. i took the prom out of the pcm and never had the problem again. the prom simply advanced timin an removed speed an rev limiters. could be an issue somewhere within your ignition circuit. im also thinking it could be a bad sensor and the pcm is compensating for wrong reading like dumping more fuel to the inkectors which is bringing your rpm's up when heat is involved. good luck!

-chris

[94 formula]

I had a very similar problem with mine and it ended up being the coil. It would run fine but before I put in my fan switch anytime the engine got over 210 it would sputter and have a really irratic idle like sometimes holding solid at 1200 rpms or it would drop to around 500 and kinda sputter.

[Jeff_in_Atl]

Here is something cheap you could try. http://shbox.com/1/4th_gen_tech2.html#ICM_cooling

[FormulaSlickG94]

Thanks for the info....greatly appreciated. A mechanic friend of mine is going to take a look a little later as well to see if he can maybe diagnose it without me spending too much more $$$. I will keep everyone posted...thanks again!