Three months and going... local mechanic shop exhausted nearly every option.. camarofourums.com has given me every option we've already tried... here goes again:

1998 Camaro, v6, 130k, auto.

This car, when warm will start and run like a bat out of hell.

When it sits overnight, and temps drop below about 40 degrees F, the car will fight you to the death about starting and staying running. It will crank and most days catch and start but you have to keep the gas pedal revved up to keep it alive. It acts like it's absolutely full of gas. It will "pop" out the front and back and not idle at all. Dies if you let your foot out before its warm. If you keep it revved up long enough to get it warm, it will then idle, then will run beautifully, and start and stop as much as you want .. until it sits overnight.

I've had one day where I get it started and running then parked it at lunch 12:00 and I can start it again at 6pm. But if it sits overnight (typically 10-11p-7:30a), then it's back to it's shenannigans.

Here goes... we've changed, replaced, tried..

Going on 3rd starter (apparently engine kick back is hard on them
Two sets of spark plugs
Plug wires
fuel filter
oil filter
coolant temp sensor
intake air temp sensor
thermostat
air filter (stock to K/N and back to stock)
driveshaft (unrelated i know, but I had to list it..)
oil
gas
can i list anything else!?

-spark plugs changed, next day were nearly soaked in gas.

-mass air flow we've tried with and without, same results

-service engine light comes and goes, but only code it throws is misfire codes on multiple cyl.. and if you heard it, you'd understand! :P

-tried putting an entirely new ignition control module in, same results..

-every sensor cleaned, then changed, except maf.. which, as above, does same with and without

-fuel pressure, injectors, all fine..

-every computer system that the local shop had has been hooked up to this car when it's warm and when cold. all readings within spec and show good bands. everything reads as if it's doing exactly what it's supposed to be doing.

-which leads us to the only guess we have left..... bad PCM?

Thanks in advance..

 

i have a 98 Z28. i have been fighting with it scince i got it. love the car itself but cannot find anyone that can diagnose the problem. i have replaced the same as you have and still no change! it runs beautifly in the summer does not matter how long it sets, but the colder weather seems to bring the problem back. my check engine light came on this morning, misfire on 5th cylinder. that is the same thing it always says but random or multiple cylinders. again like you, once the car warms up and the gauge reads a temp, it will run like a bat out of hell.

i have replaced....
temp sensor
air temp sensor
plugs
wires
oil
oil filters
air filters
thermostate
flushed/replaced anti-freeze
new battery
new alternator

i have also taken my car to the chevy dealershipe and they tell me the same thing. misfires, do a tune up. of course they look at me like i'm stupid when i explain what is going on (probably because i'm a girl) and i never get any straight answers.

anyone that can help or give suggestions will be greatly appreiated!!!

 

check your voltage across your cts plug and verify wires to ecm are not shorted to ground at your cts plug you should have 5 volts let me know what you find out

 

i had a similar problem with my 01 and i figured it out. on your throttle blade theres a hole or there should be a hole through it and if not there needs to be one i think i used a 5/16th drill bit if im not mistaken and that gave it the air it needed at start up.

 

I had a 99 that I drove for 8 years. I used to live up in Buffalo, so when the snow started coming down, it could be trouble. Especially in the later years. But..its a Camaro. And when its not winter, it almost seems worthwhile, doesnt it?

 

Ok lets start with the basics. What year? is it a V6? When did you last change the battery? When was the last tune up? (sparks, wires, so on) What is the mileage? (ruff not exact) Is the problem similar? does it do it all the time? is it loosing coolant? <--(Main one you want to answer)

Lets start there and move on

 

Did anyone ever change the injectors, if not you should look into taking them out and having them checked.

My guess is the injectors are leaking down, and you are trying to start an extremely flooded engine.