Rough idle for 5 seconds with black smoke - Third Generation F-Body Message Boards

turbotransam83 · 06-13-2009, 06:05 AM

ok so i have recently picked up a 1989 camaro rs with the 305 tbi/auto.

I am having a weird issue when i first start the car. When i first start it it basically loops and misses bad and black smoke pours out my exhaust. only last for about 5 seconds or so then the car idles up and runs fine.

The wierdest part about it once it starts i can lightly rev the motor and it will still miss and jump around. if i keep reving it it will sit there and pour out black smoke. if i start it without hitting the gas it only does it for about 5 seconds. The SES light does come on after the 5 seconds and stays on.

now i can see that its running a little rich after the idle picks up but it runs smooth and idles fine in gear. the problem persist rather im starting it for the first time or i have driven miles and stop and start it. i have rebuild the TBI unit it was pretty clean to start. replaced the fuel pressure regulator.

any sugestions on where to start would be helpful lol.

now on a side note the guy i bought the car from worked at a dealer and they degreased the engine and sprayed on that almost like tire shine stuff all over everything and i mean everything lol. may that have fried some sensors?

afremont · 06-13-2009, 09:28 AM

First you need to extract the code the ECM is setting when it turns the check engine light on. I can tell you though, it's probably a coolant temp sensor.

turbotransam83 · 06-13-2009, 03:09 PM

thanks i`ll start there i have found that the gauge doesnt work on the dash for the coolant so i`ll check it out thanks.

turbotransam83 · 06-14-2009, 06:29 AM

update.... i had some time yesterday before the car show to check under the hood some and found the problem.

The vacuum line running to the map sensor was completely off. not only off but removed in general.

seems the previous owner had a leak in the small 3 way check valve in the rear of the motor and instead of going to the autoparts store and spending 3 dollars on a new one the felt that orange silicone would fix the problem and they removed the map sensor vac lines with it.....

car runs great now except for the dead battery im having lol oh well thats an easy fix.