Hello Everyone,
The '93 940T has been running wonderfully of late and then suddenly ...

1] Starts right up but will not hold an idle when cold - need constant pedal to keep it from stalling
2] Once warm, the idle pulses like a heart beat. It falls but then kicks back up again to 7.5 in a perfect rhythm - at least one cycle per second. No need for any pedal to keep this going.
3] When accelerating rapidly - and thus engaging the turbo - the car loses power. No missing or jerking - just a smooth lack of power.

No engine codes.

So these symptoms scream air hose leak to me. I've wrapped my hands around the various hoses and found nothing. Does the collective wisdom of Volvo Forums have any thoughts or suggestions? I suppose replacing all hoses is the blunt approach, but I'm hoping for a more strategic approach. I searched this set of symptoms, but found nothing.

I cleaned out the idle valve. No help. Only other recent operation was replacing the AC condenser - a puncture to the intercooler a possibility?

Thanks.

 

Yes, that intercooler/associated piping and hoses hole is definitely a possibility! And it's hard to find since it's behind and under things.

 

Problem solved. The lower hose connection to the idle air control valve was not clamped completely - the clamp needed about two added rotations with the screwdriver . So, in the end, my poor running issues appear to have been resolved by cleaning out that valve housing and then properly clamping the hose to the valve. Amazing how a slightly loose hose fitting can cause such terrible performance.