Car conks out when coming to a stop

[Bruce Hazell]

Hi all...I have a 91 ZRF-1..modified somewhat many years ago by Haibeck so his chip is in there:}
Anyway over the years but more recently when coming to a quick stop or slow down with clutch disengaged quite often the revs bounce down from just under 1,000 which seems to be normal idle speed to around 800. Sometimes bounces back up to 1,000 or if not conks out. Restarts ok.

Can be a little dangerous if turning as power steering of course dies not to mention its embarrassing as hell at a set of lights. If I turn the AC on which cause the revs to drop a tad at idle it is almost guaranteed to conk out as coming to a stop.
When just sitting idiling in my driveway this does not happen AC or no AC.
Any thoughts as to what may be the cause or the solution.
Back in the day would just turn a screw and increase the idle..hahaha!

[secondchance]

I would first remove Idle Air Control solenoid on the front passenger side. Remove and clean inside passage on the intake plenum as well as the cone shaped pintle on the IAC.
If this doesn?t work, consider adjusting the throttle stop on the throttle body. It has a lock nut on small allen head bolt.
I would give Marc a call especially if he had worked on the motor.

[1991 Corvette ZR-1]

Your MAP sensor line is full of oil. Remove and clean it out. Exact same symptoms I experienced. Always happened slowing to a stop or enough to make a turn, then mid turn car would die.

[secondchance]

Your MAP sensor line is full of oil. Remove and clean it out. Exact same symptoms I experienced. Always happened slowing to a stop or enough to make a turn, then mid turn car would die.

Also, check and make sure you have a correct PAP sensor line (hard plastic with rubber connectors). Soft vacuum line will collapse during idle and choke off MAP reading.

[mlipmd]

For a different problem or solution maybe - FWIW, my car once stalled a few times at a stop sign, restarted easily. Drove home 5 miles without a problem. Turned out it was out of gas even though the dash gauge said I had 1/8 tank left. Never had another problem since I refilled it and I never let it get that low again and reset my trip meter each time I fill up to be aware of how far I went. Common problem with the gauge and deposits on the fuel sender. With the C5 I had this was a known common issue with them and could be solved by adding Techron into the gas tank every few fillups to keep the coils in the sender clean. I'm going to try this for the next few fillups to see if my gauge can get anymore accurate readings and because that's really a problem when your car just dies like you describe.

[XfireZ51]

I know mine will run out of gas w gauge on RESERVE and one line left. If it says Range is 40mi, I?m about to come to a halt.

[Bruce Hazell]

Thanks all..will check out your suggestions!!!

[WARP TEN]

I ran into the same problem right after Marc finished his 510 HP package on my '95. I brought it back down to his shop and he made a slight adjustment to (I think) the throttle stop or something else up near the throttle body. That fixed it so I suggest that, if you have not yet, you call Marc and ask about that solution. Sorry I can't quite remember what exactly he adjusted, but it solved the problem of dying when coming to a stop. --Bob

[Bruce Hazell]

Just in checking..is the MAP sensor removal and hose removal /cleaning an easy step as in not likely to screw it up?? I have the original manual so know where they are.

[secondchance]

Just in checking..is the MAP sensor removal and hose removal /cleaning an easy step as in not likely to screw it up?? I have the original manual so know where they are.

Removal is easy. Cleaning the hose is easy. Sensor itself? If failed, cleaning won?t help. Also, make sure you have a hard plastic hose. If soft rubber hose, will collapse as you decelerate and give false reading to the sensor resulting in a stall.