940 GLE saloon twin cam 16v, idling problems, and other...

LankyTim · Nov 6th, 2003, 10:48

Hi,

Ive recently bought a 1991 H reg 940 saloon 16 valve twin cam. There seems to be a problem with the idling though, it idles unevenly and somtimes even cuts out when stationary at lights e.t.c Ive wound up the idle speed and this seems to have made a difference, but its still not right. Also when the car is hot, say after 20 mins driving the throttle will stick open on gear changes, e.g ill close the throttle as I change up from 1st to second at 3000 rpm and instead of the revs decreasing between the gear change, they will stay at 3000 rpm. As I go into second the car will jolt as the engine will be revving too fast for the gear. This can be very frustrating and spoils the bullet proof volvo driving experience we all like! Ive checked that the throttle cable isnt sticking at all so at the moment im mystified. Also, when accellerating you can somtimes "sense" a misfire, the car doesnt seem to be producing full power but this doesnt happen all of the time, only somtimes. Fuel consumption also seems to be high (though maybe just a 16 valve trait?)

Id love to sort out these little niggly faults as apart from this the car is practically A1 though as it is getting old I dont expect it to be perfect.

any advice would be very much appreciated!

Regards

Tim Rodgers

lankytim@hotmail.com

LankyTim · May 1st, 2005, 23:36

Just to update myself. FINALLY got a mechanic to take a look. He plugged his computer into it, and it said that there was petrol in the oil, causing petrol vapour to be sucked through the crankcase breather into the inlet manifold, confusing a sensor that lives there and telling the engine that there is too much fuel in the mixture. The "brain" then tells the mixture to lean off when it shouldnt do, causing the idle speed to go crackers. The varying amount of fuel vapour in the oil causes the different idling speeds and the "sticking" at 2k RPM that often happens.

Apparently the cause of the petrol in the oil is a worn engine :(

Should a volvo engine be worn at 87,000 miles? I shouldnt have thought so! Its been very well maintained! It doest smoke or rattle and apart from the funny idling, runs perfectly now.

The "cure" for the errant petrol vapor confusing the sensor? disconnect the crankcase breather!

Im still testing the car to see it it has worked. Im hoping that it hasnt as this would just confirm that the engine is indeed worn. Im hoping that it may just be a dirty sensor.

Lets hope!

Tim

Nov 6th, 2003, 10:48	#1
LankyTim Missing the point Last Online: May 1st, 2024 18:59 Join Date: Nov 2001 Location: Stoke-On-Trent View Photos By: LankyTim	940 GLE saloon twin cam 16v, idling problems, and other... Hi, Ive recently bought a 1991 H reg 940 saloon 16 valve twin cam. There seems to be a problem with the idling though, it idles unevenly and somtimes even cuts out when stationary at lights e.t.c Ive wound up the idle speed and this seems to have made a difference, but its still not right. Also when the car is hot, say after 20 mins driving the throttle will stick open on gear changes, e.g ill close the throttle as I change up from 1st to second at 3000 rpm and instead of the revs decreasing between the gear change, they will stay at 3000 rpm. As I go into second the car will jolt as the engine will be revving too fast for the gear. This can be very frustrating and spoils the bullet proof volvo driving experience we all like! Ive checked that the throttle cable isnt sticking at all so at the moment im mystified. Also, when accellerating you can somtimes "sense" a misfire, the car doesnt seem to be producing full power but this doesnt happen all of the time, only somtimes. Fuel consumption also seems to be high (though maybe just a 16 valve trait?) Id love to sort out these little niggly faults as apart from this the car is practically A1 though as it is getting old I dont expect it to be perfect. any advice would be very much appreciated! Regards Tim Rodgers lankytim@hotmail.com

May 1st, 2005, 23:36	#2
LankyTim Missing the point Last Online: May 1st, 2024 18:59 Join Date: Nov 2001 Location: Stoke-On-Trent View Photos By: LankyTim	RE: 940 GLE saloon twin cam 16v, idling problems, and other... Just to update myself. FINALLY got a mechanic to take a look. He plugged his computer into it, and it said that there was petrol in the oil, causing petrol vapour to be sucked through the crankcase breather into the inlet manifold, confusing a sensor that lives there and telling the engine that there is too much fuel in the mixture. The "brain" then tells the mixture to lean off when it shouldnt do, causing the idle speed to go crackers. The varying amount of fuel vapour in the oil causes the different idling speeds and the "sticking" at 2k RPM that often happens. Apparently the cause of the petrol in the oil is a worn engine :( Should a volvo engine be worn at 87,000 miles? I shouldnt have thought so! Its been very well maintained! It doest smoke or rattle and apart from the funny idling, runs perfectly now. The "cure" for the errant petrol vapor confusing the sensor? disconnect the crankcase breather! Im still testing the car to see it it has worked. Im hoping that it hasnt as this would just confirm that the engine is indeed worn. Im hoping that it may just be a dirty sensor. Lets hope! Tim

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