1994 Volvo 850 6 cyl Front Wheel Drive Automatic 197K miles
My daughter 94 Volvo 850 has developed a habit of stalling after it warms up. Generally after driving several miles. This started last fall and before I got a chance to figure out the problem the weather got cooler and it seemed to have gone away. However, now it is back. Once the engine sits for about 5 minutes or so after stalling, it will start right up again. Most of the time it stalls when slowing down or coming to a stop but has done it while driving. You can sometimes keep the enginge running if you keep the idle up with your foot on the brake and the other on the gas.
I thought I would go ahead and copy down the fault codes and see if I could track the problem, but when I removed the covers from the diagnostic unit I discovered the test button missing (Not in the socket) and someone had snipped the diagnostic lead wire. Did I mention my daughter bought this as a used car? Someone must have had a bad day.
When it idles in the driveway after you first start it, it does not not power surge or drop, just runs at a steady rpm. However, after idling for about 4 or 5 minutes the idle seems to get a little rougher, but the rpms still stay stead at about 850-900 rmps (Same as when it was started).
After idling in the driveway for a long lenght of time, if you run the car up to about 2500 rpms, sometimes when you take you foot off the gas it will drop down to about 600 rpms and then surge and drop back down to the low rpm and bounce back and forth. Then if you run back up the rpms and take your foot off the gas it will settle back to the 850-900 rpm and idle fine. It does not seem to matter if you quckly run the rpms up or slowly run it up and then let off the gas. You get the same response.
It has been less then 10k since plugs etc changed and I can not seem to locate any vaccum leaks. I have considered replacing the fuel filter, but that did not seem to cover all the symptons. Any suggestions?
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Wednesday, April 9th, 2008 AT 10:48 PM
