940 with hesitation under load & a fluctuating RPM needl

cr4b · Post by **cr4b** » 13 Mar 2006, 16:12

Hi, this is my first post here!

Some time ago my '91 940 GL had problems with starting when cold. Then I had the problem fixed by a mechanic, but he couldn't fix it completely. Now the car does start, but after the engine warms, it starts to hesitate under load. Also, the RPM needle fluctuates strangely. However, the ODB shows no faults.

The mechanic had changed the RPM sensor and the ignition power stage. I tried to swap back to the old RPM sensor, but the engine refused to start with it. Also the ODB didn't get a signal from the sensor at all.

Should I try buying a new RPM sensor or do you think it might have something to do with the power stage? Or maybe it's somethin else?

cr4b · Post by **cr4b** » 14 Mar 2006, 14:01

Ok, I tried disconnecting the Air Mass Meter. The car actually ran better, there was less hesitation.

Does this mean that the Air Mass Meter is the problem, or does it mean that the problem is elsewhere and disconnecting the AMM just helps for some reason?

cr4b · Post by **cr4b** » 20 Mar 2006, 23:09

Problem (almost) solved.

I changed the ignition cables and spark plugs, and now the car runs totally fine! Except for the RPM needle, which still is all over the place. Weird, huh? I hope this post will help someone with similar problems.

Post by **matthew1** » 20 Mar 2006, 23:18

This thread may help with tach needle moving around:
https://www.matthewsvolvosite.com/chat/p ... light=tach