Hello all my name is: Cristian
I have a: 1991 3000GT SL, Auto Trans
I’ve got quite a conundrum here, hopefully someone has experienced it before!
When the car is running and at idle (in any gear) it often surges and stalls.
From what I have been experiencing, I believe most (if not all) instances of surging or stalling occur at the first introduction of a large electric load (radiator fans turning on mainly) and/or shifting into drive or reverse. It also occurs when I slow down to a complete stop (stop sign, red light, etc.). The engine will experience a very steady surging while at idle until it inevitably stalls, I believe only if there is a load on the electric system.
The engine never stalls, surges, or bogs when the throttle is open even in the slightest. My current way to combat this stalling when coming to a stop is my giving the throttle just a hair of a touch at all times, even while braking or at a stop.
This issue occurs almost exclusively when the engine is warm and fully up to operating temperature. When I start it up in the morning on my way to work it runs perfect until a few miles down the road when its all warmed up.
So far I have:
- Replaced the idle air control valve
- Checked all hoses for vacuum leaks (none found)
- Disconnected brake booster and plugged off orifices to check for a diaphragm leak (no luck here)
- Replaced the PCV valve
- Cleaned the throttle body opening (held throttle open and carefully wiped out build up with rag)
- Just had a new timing & serpentine belts put on, along with spark plugs and ignition wires
- Monitored voltage at battery while car was running and during a stall (12.6V Off, 14.1V Running)
I think I’ve ruled out my alternator and voltage regulator just by monitoring the voltage at the battery and watching it for fluctuations, looked all good there.
As I mentioned, the catalyst for the surging/stalling seems to be the radiator fans turning on. The fact that it only happens while I’m at idle is what’s really puzzling me here.
Side note - not sure if this is applicable at all but worth mentioning - my tachometer doesn’t work at all, like it just reads 0 at all times.
If anyone has any ideas I would love to hear them, even if they are just shots in the dark!