Stall when start and deceleration

[Ridman]

Ok I have a 1987 and every once in awhile it will not idol on start up and will die on deceleration. I thought this was old gas (and it might have been) because it was bad for a while and then got better. The problem went away for awhile. I have had 2 times in the past week or so were I noticed a electrical issue then the car wouldn't want to idol on start up. Ok that was painful to spit out. Let me explain, the other day I drove the car and everything was fine. I parked it and about 2 hr's later took it out again still fine. I made 2 stops and on the 2nd stop when I went to start it up it didn't want to idol. So I thought ok it is the old gas or dirt. As I was driving it I noticed the auto climate control wasn't working properly. I put her away and the next day when I started it up no problems( and the auto climate control was working fine again). Then it ran great for about a week and tonight I did almost the same type of thing as before, but this time when I went to shut it off at my 2nd stop, and turn off the headlights the lights went out but they didn't go down. I turned them on and then back off and they went down.(no big deal right) when I came out after about 15 min and went to leave it didn't want to idol? This time it don't last very long and never died on deceleration. So now I am wondering if the idol issue is a electrical thing that is coming and going? It doesn't happen very often but lately when it does I seem to have something electical messing up to. Any thought?

 

[gmjunkie]

Ok I have a 1987 and every once in awhile it will not idol on start up and will die on deceleration. I thought this was old gas (and it might have been) because it was bad for a while and then got better. The problem went away for awhile. I have had 2 times in the past week or so were I noticed a electrical issue then the car wouldn't want to idol on start up. Ok that was painful to spit out. Let me explain, the other day I drove the car and everything was fine. I parked it and about 2 hr's later took it out again still fine. I made 2 stops and on the 2nd stop when I went to start it up it didn't want to idol. So I thought ok it is the old gas or dirt. As I was driving it I noticed the auto climate control wasn't working properly. I put her away and the next day when I started it up no problems( and the auto climate control was working fine again). Then it ran great for about a week and tonight I did almost the same type of thing as before, but this time when I went to shut it off at my 2nd stop, and turn off the headlights the lights went out but they didn't go down. I turned them on and then back off and they went down.(no big deal right) when I came out after about 15 min and went to leave it didn't want to idol? This time it don't last very long and never died on deceleration. So now I am wondering if the idol issue is a electrical thing that is coming and going? It doesn't happen very often but lately when it does I seem to have something electical messing up to. Any thought?

First off, CHECK ALL Grounds on Chassis,Engine and Battery cables!! Second check the 1 way vacuum valve on Intake!! Third Check EGR for a piece of Carbon stuck in it!!

 

[TedC]

Attach a VOM and monitor battery voltage during these conditions. When running, you should see volts in the 13.8 to 14.1 range. The dash should also be reporting similar readings. I would remove and clean the throttle body, and make sure the Idle Air Control (IAC) is clean. I'm amazed at the crap that builds up on the IAC, especially with an oil based air filter (i.e. K&N). You can then reset the TPS when you reinstall the throttle body (.54V at idle and at least 4.5V at WOT). I picked up a TB gasket kit from AutoZone for around $10. Also, measure the resistance across each fuel injector with the connectors off. Make sure they all show similar values.

 

[Ridman]

OK Thanks guys I will check all these things.

 

[Radar]

I would also check the exhaust gas recirculation system (EGR). On the Corvette, there is a valve mounted on the intake manifold and a electronic proportioning valve that the ECM uses to "talk" to the EGR valve.

I had a car once that did what you are refering to and it was the EGR valve sticking open. Sometimes it would "fix itself" and be fine for months. But when that valve sticks partly open, the engine will not idle and has a tendency to lean out while coasting causing it to stall. And to make it worse, it does not set a code so the check engine light never comes on.

Hope this helps.

Thanks,
Radar

 

[clok1966]

You ever get this figured out Ridman? My 87 i just bought is doing same thing, runs great but if you come to a stop sign or even just shift it out of gear and let it Idle it runs to 5, then 3, then chokes out and dies (RPM). it starts perfect, but unless i keep my foot on it it dies right away. No lights, No codes. SInce i have only had it a day i cant say for sure but I drove it alot tonight and it did it, then it was fine then it did it again. Tongith on drive home it died at evry light/stopsign (wow, waht fun is it to drive a nice car and have it die at every stop Im embarassed). Going to take out EGR tomorrow and check it.. had a olds 350 that had a bad EGR but it would flood.. so i wasnt thinking that but seems like thats the place to start.

Clok