Why would my car stall at a stop light. Mainly with the AC running.

VBWOLPERT

MEMBER
1992 HONDA PRELUDE
160,000 MILES

New timing belt New idle air control motor. Cleaned and adjusted fast idle air control valve ( thermo valve on d-side). Cleaned t-body. Have base idle set to 700 -+50rpms. Timing set to emissions sticker. New distributor, coil, wires, and plugs. Have used carb cleaner try to find a vacuum leak and no change in idle. No codes found. Check and purged all air pockets in cooling system using air bleed screw and a bottle over radiator filler neck to raise coolant level. One weird thing if I plug the hose coming off the air boost valve on the far end of the intake from the t-body the idle will start to surge from 800 - 1500. Not sure why it does that. The stalling problem is worse when the ac is on. Any help is welcome. Thank you.

3 Replies

KHLOW2008

MECHANIC
41,814 POSTS

Check the valve clearances. If they are too tight, it would result in erratic idling and stalling.

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Wednesday, September 19th, 2012 AT 9:00 AM

MICHAELDAVIS1

MEMBER
2 POSTS

Well it probably 2 thing first one the fast idle air control valve ok if this is the valve that is hook to the throttle body underneath it if that the one you talking about that you Cleaned and adjusted then it could be it. There is no way to adjusted them the are adjusted coming out of the factory. What everyone says online is bull shit. Just replace it I had the same problem tried to adjust it still did it looked further online and found out what I stated there not to high price on ebay not like the iac valve and it fixed it I would try that second sorry wrong order I would take the IDLE AIR CONTROL VALVE that on the side of the intake off and see if the screen is dirty and clocked and clean the screen and the rest of it and see what happens. Then I would replace the fast IDLE AIR CONTROL VALVE. And if that still didn't work then I would buy a used IDLE AIR CONTROL VALVE cause I new one like $250.00 used one on ebay are like $50.00. I've had both thing on my 1992 prelude and this first time it was the fast IDLE AIR CONTROL VALVE and today I just had to change to a used IDLE AIR CONTROL VALVE that IDLE AIR CONTROL VALVE really my fault long story I would bet one of them 2 thing will fix it sorry so long hope it work not a car mechanic just know from working on my own lude