1994 volvo 850 stalls when reaches temperature

[julesatuk]

A year ago I had a new coil fitted and ran the car until May. It was then made SORN until November with the occasional running of the engine. But then I got it on the road again and it suddenly started to suffer engine failure. What happens is, if I run it stationary it will start happily and tick over nicely for about 5 - 10 minutes and then as the engine temp comes up to running temp, the engine starts to stammer and then if I apply throttle it stutters and stalls immediatly and will not restart until cooler.

[erikv11]

Are there any codes? If so, read them and list them!

Will it stall no matter what at 5-10 minutes, or only if you apply throttle? In other words, could you let it idle for an hour, or would it still shut down if idling.

A couple things come to mind:

(1) Something gets warm, then doesn't work right: this points to an electrical part. As they heat up, resistance goes up, then gets too high. This could be a relay (fuel pump relay?), a wire (battery positive cable - does it get hot?), or a sensor (cam position sensor?). Then when the part cools off, it works again.

(2) 5-10 minutes is when the car goes into closed loop mode. Maybe there is a seriously bad oxygen sensor.

During the time it won't re-start:
- is it turning over normally just the spark won't catch, or does it act like the battery is dead?
- is there fuel pressure at the fuel rail?
- is it making spark to the plugs?

[Ozark Lee]

Another place to look is the ECT sensor. Does the temperature gauge on the instrument cluster behave normally?

...Lee

[erikv11]

Lee is so smart! I agree: ECT should move to the top of the list of suspects.

[julesatuk]

Thanks everyone, I don't have any codes yet, not sure about fuel and sparks, but engine turns but doesn't catch, temp gauge seems to behave normally. Idles and stammers, could probably sit and idle like that ok. Apply throttle and that chokes it.