well since i got my iroc, things have been going good. well now i was driving along and i tryed speeding up, and i got nothing, and it kept getting worse and worse, it jerks, it doesnt want to shift, right and my gas milage was horrid. now she tops out at 35mph, theres a loud noise coming from way back on the drivers side, maybee neer the transmission. fuel pressure is up around 45psi, any ideas where i can start?

ive recently changed the plugs, wires, cap rotor, fuel filter so those are all good

 

I have an '86 Iroc that did exactly what you discribed. I finally took it to a GM shop (good rep, and have all the tools) and they told me my EPROM was bad. The chip was an aftermarket chip is what they told me. They said computer was likely the culpret however. They said the computer itself can cause the chip to go bad. Like you, tune ups were all recent and this problem pretty much happened over night. THe only problem I had before this was slight hesitation when I tried to give it Full throttle from a dead stop. The only mods I have done to my car is a K&N, MAF screen removal, and an air foil.

The quote for replacement parts that the GM shop quouted me was $45 for the stock prom chip, $35 for some other sensor that I have to find out was, and $220 for an aftermarket computer that supposedly fixes some of the problems in my stock one.

Hope it helps and tell me how it turns out.

 

hmm did it have the same kind of noise also? like compressed air? i know the chip in there is the wrong one, its for a 305, and the guy dropped in a 350, i have a new one in the mail, maybe that will fix it, do you know any of the part numbers or manufators names that fixed yours?

 

Have you tested the fuel pressure while you were driving? My car had a problem simmilar to the one you are having. It turned out to be the fuel pump giving out when it got warm.

 

The sensor they told me needed replacing was the manifold temperature sensor. There is a couple of different designs and the part number I have is for the 1st design. That part number is 25036751.

They told me they didn't have a part number listed for a replacement chip or computer.

When they were diagnosing the problem they did check my fuel pressure and pump and said it was just fine.

 

Year one sells that manifold temp sensor for $9 if I saw that right.

From another post I posted I would take the advise of finding a stock replacement from a salvage yard or ebay. I ended up buying one from ebay with the prom chip.

$50-80 for a used ecm is about right. I also read up on one of my camaro repair books and I guess if the prom goes bad the computer will go into "limp" mode which is like a very limited hardware prom that will basiclly just allow the car to "limp" to be repaired.

Anyway that is my experience so far, but the best thing for sure is to spend the $20 diagnostic fee and just take it to a reperable GM shop that has all the diagnostic equiptment and find out what they say. You might still have to weave through what they say you really need and what you should have replaced, but it should narrow the field.