Stutter at idle

fartoright · Post by **fartoright** » 24 Jan 2017, 18:13

1989 245 dl. When I'm stopped at light with foot on brake the engine will stutter for a half second. The first time it did I thought someone hit my car. Started a month ago and would not happen often but now it happens about every 10 to 15 seconds while stopped. Does not happen while driving or accelerating only when stopped. Thank you for any advise.

mydamnvolvo · Post by **mydamnvolvo** » 24 Jan 2017, 20:20

This happens on my 960. Fuel system cleaner helps, but it is probably a firing issue. Check spark plugs and try running fuel system cleaner and some good higher quality gasoline through it.

lummert · Post by **lummert** » 24 Jan 2017, 23:22

Brake booster?

fartoright · Post by **fartoright** » 25 Jan 2017, 18:39

I have a short day at work tomorrow. I'm going to change spark plugs cuz I just replaced mass airflow sensor. Car was running ruff and fuel was rich. You mentioned brake booster? I assume you are referring to a vacuum leak. I will double check tomorrow. I checked before saw nothing abvious but I'm going to take a closer look. Where is the leak most likely to be?

93Regina · Post by **93Regina** » 25 Jan 2017, 19:57

fartoright wrote:1989 245 dl. When I'm stopped at light with foot on brake the engine will stutter for a half second.

Brake booster's diaphragm and/or its check-valve may be the issue.

fartoright · Post by **fartoright** » 29 Jan 2017, 14:53

I changed the fuel pressure regulator. Spark plugs. And a used Bosch MAS. The car had a made in China MAS on it from previous owner. I increased the idle. It was idling way to low. She runs great now. I'm not sure what fixed it. The brake booster hose was fine. I took it off and inspected it. Thanks for all the advise.

93Regina · Post by **93Regina** » 30 Jan 2017, 06:24

fartoright wrote:I increased the idle.

LH 2.4 idle adjustment FYI

fartoright · Post by **fartoright** » 31 Jan 2017, 14:11

Thanks for that info. I have a friend who has had 240 and 740 s for 35 years. He ran me thru how to do it correctly. His phone calls sounded a lot like your article.