Engine dies with a/c or heater on

[jthod]

I thought this problem had gone away with new battery and cables, but its back. Any time the A/C or heater are on, coming to a stop, and the clutch is depressed, the engine will just fall off. Now that I know this happens, I can watch the tach, and when the engine gets to about 1k RPM, tap the gas and it goes back up and will stay up. This isn't a huge problem, except when driving in town, when I don't always get a chance to tap the gas, and have to re-start the engine.
Any help would be greatly apreciated.
Please don't tell me it's the CPS!

 

[Denny]

Check EEC for codes. I would think IAC valve though. When you put a load on the engine via AC or heat some more air needs to come in at idle, this may not be happening.

 

[NotSoSlowSHO]

What he said

Idle Air bypass valve.

Replace it, reset the idle, and enjoy!

 

[Mark in PDX]

Also, I had this problem and it turned out all I had to do was reset the idle.. It was programmed w/o the AC on and when the compressor kicked in when I was coming to a stop the car died...
Try this first, then clean the IAB, as that happened to me 1x also (different car).. Then if both those don't fix it, take a HARD look at the ac clutch.. I had an aftermarket compressor clutch installed and it melted and was creating a huge amount of friction when it came on.. When I pulled it off I could not believe the engine kept going with that on there.. (another car)...
Have fun!

 

[itwonder]

Also, I had this problem and it turned out all I had to do was reset the idle.. It was programmed w/o the AC on and when the compressor kicked in when I was coming to a stop the car died...
Try this first, then clean the IAB, as that happened to me 1x also (different car).. Then if both those don't fix it, take a HARD look at the ac clutch.. I had an aftermarket compressor clutch installed and it melted and was creating a huge amount of friction when it came on.. When I pulled it off I could not believe the engine kept going with that on there.. (another car)...
Have fun!

x2 on resetting the idle program. Do a search and you'll find the procedure. When you first start the car after the battery has been disconnected, always turn the A/C and headlights on immediately so the PCM sets the idle with those loads applied. I had the same problem on mine, and that's all it took. I agree with the IAB as the second step if required. They are only about $43 from Advance Auto.

 

[shoclown]

i would check i idle air control...it is a stepper motor that basically drives a cork into a vacuum port that is leaking... vacuum leak causes idle to increase so if it is completely open at step one say engine idles at 2100 rpm and with motor all the way in step 100 idle is determined by throttle plates only around 500 so iff you set it at step 80 it allows a little bit of a vacuum leak and idle might go to 900 ( numbers are not actual just theory to explain).

problems that might cause your concern.
1. motor not working broken
2. some one tried to set the idle by adjusting throttle plate 9ecm and actual throttle angle dont match)
3.the vacuum pasage that the motor controls is plugged up with carbon and crap so if motor opens all the way the idle still wont change becouse carbon has sealed the vacuum passage.

I would start by removing the throttle body and iac motor and physically looking into the manafold to check passages (easyier if upper intake and runners are removed )