Volvo: volvo 940 turbo 1993, volvo service, volvo 940

Question
QUESTION: Hi

My Volvo 940 SE Turbo 1993 120K is in excellent condition with a full Volvo service history.  On 3 occasions since Christmas, on a very cold morning, the engine would start first time but would idle very roughly for about 10 to 15 seconds and then idle perfectly.  When this happens, the engine sounds as though one or two of the cylinders is not firing.  Any idea? Could it be the cold start valve?

Please let me know.

Thanks

George


ANSWER: George,
Most likely it is missing and needs a tune up. Sometimes it take a few seconds for all the cylinders to fire up in the extreme cold. You can start by tuning and performing a intake system cleaning, and cleaning adjusting the throttle housing. If all that is/has been done let the engine warn a few minutes before driving. Your car should not have a cold start valve. There have been some cases where the intake valve has carbon deposits and soaks up the gas so the cylinder will not fire. The intake cleaning can fix that. You can remove the intake manifold to inspect the intake valves.

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QUESTION: Hi again,

Thank you for your reply, I will get that checked out, could it also be caused by a dirty or faulty injector?

One thing I have noticed is a very slight drop in revs when I turn the warning lights on.  When they flash the engine revs very slightly fluctuate.  Is there anything that I need to worry about, ie a future problem with the electrics / fuses?

Thanks again


Answer
George,
Dirty injectors, yes possible. Faulty one, I do not think so. If one was faulty then why would it run good warmed up? Many times when there is a demand on the charging system (turning on lights, etc) the engine bogs as the charging system puts out more electricity. As the demand increases the alternator turns a bit harder so that the electrical power can be made, that in turn is a "load" on the engine.