Volvo 940 Starts then dies very occasionally

[Pete940]

Seems to start after a similar number of cranks as mine, but I can see that the revs don't immediately rise to normal idle speed. Did you clean up the throttle body and idle control valve? (Be gentle with the throttle body gasket if you take it off)

[Eyebrows123]

Normally it seems to take a couple more cranks than what it did on the video but it never rises to normal idle speed any faster than what it did on the video. I pulled the intake pipe off the throttle body and it seemed pretty clean inside so I assumed it didn't need a clean, I'll try get a picture of it later. Haven't looked at the idle air control valve, I'll try have a look later, is it the bit below the throttle body?

One thing I noticed was the lines going to the charcoal canister are rather cracked, I think they're vacuum lines but could that be a cause of a vacuum leak that could affect idle or not?

Cheers for the help

[Eyebrows123]

Ok, had another look today. The throttle body really does look clean, the idle control valve looked a little dirty, like a bit of oil residue at the bottom, but no carbon build up, didn't look that bad.

I did notice three failing vacuum lines though, one from the EGR valve to something on the side of the car and the two to the charcoal canister, I'll get these replaced but could a vacuum leak from these cause bad running?

Fuel pump relay wise, I think I can only feel the relay clicking when the engine is cranking, I don't think I can feel it clicking when the ignition is turned to on and I can't hear the fuel pump either.

Also, all the HT side of things were replaced 2 years (10,000 miles) ago so I'd be surprised if it was them causing the trouble.

[TonyS9]

Looks pretty normal to me, same as my sister 97 auto. The later engine mgt seems to do that (lazy rev up) more that the earlier one which gives it a blip when it starts (eg 95). Having said that, that and the very low CO % I get in the MOT makes me think there is something wrong with her car.

[Rversteeg]

For some time I have been driving with an older ECU version (because of immobilizer problem) and I did notice a difference in starting. When the engine picked up it seemed to overshoot a little before settling at 850 rpm. I now have the last series ECU (-984) back in again and this let the engine rev up slower when it picks up after cranking. So that is normal.
Although it seems clean, I would still use some brake cleaner and wipe out the internal of the throttle body. Just take the air inlet hose of, open the throttle flap en wipe it clean with a brake cleaner drenched cloth. It is only a small aperture that is easily clogged.

[jimmk3]

Apologies for resurrecting an old post. But did the OP fix this problem in the end? I was planning on starting a new post, however I came across this issue which sounds very similar to the one I am having on my 940 2.3LPT. It very occasionally starts then stalls immediately when the engine is hot/car has been taken for a run. Sometimes it doesn't quite stall and recovers. Other times it is completely fine and no issue. This is always from hot. Cold start I see no issue. It does also seems a little lazy in terms of reaching idle speed as an earlier post mentioned, but am unsure as to if this is an issue or just characteristic of this engine since I haven't had the car long. Any help would be great! Happy to start a new post if preferred. Thanks. Jamie