2002 Mercedes C320 Rough Idle while in gear.
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2002 Mercedes C320
2002 Mercedes C320 Rough Idle while in gear.
Hi folks,
I have a 2002 Mercedes C320 with 56k miles on it.
Recently, the car started to idle rough when in gear (but stopped).
It idles fine and smooth when in park/neutral.
I changed the spark plugs, the air filter, the fuel filter, and that did not really help. I checked the vac lines and they don't seem to have any wear/leaks...
I hooked up an OBD II scan tool and didn't get any fault codes.
The reading on my tool was (when the car was in gear idling):
Rev: 553-564rpm
Intake: 52-58kpa
MAF 5.4-5.5
Timing -14.5degrees
When the car was in park/neutral
Rev: 690rpm
Intake: 42kpa steady
MAF 5.0
timing: -16degrees
Any idea what might be causing the rough idle? I did some search on the forum, and looked at what others posted that might be suspect.
The things I haven't checked are
1. the motor mounts (which I think is unlikely in my case, since I would think it would be idling rough both in and out of gear if that were the case)...
2. The MAF/throttle body... The idle is silky smooth in gear, but when in gear, the idle drifts between 550-565 RPM....
Any ideas?
I have a 2002 Mercedes C320 with 56k miles on it.
Recently, the car started to idle rough when in gear (but stopped).
It idles fine and smooth when in park/neutral.
I changed the spark plugs, the air filter, the fuel filter, and that did not really help. I checked the vac lines and they don't seem to have any wear/leaks...
I hooked up an OBD II scan tool and didn't get any fault codes.
The reading on my tool was (when the car was in gear idling):
Rev: 553-564rpm
Intake: 52-58kpa
MAF 5.4-5.5
Timing -14.5degrees
When the car was in park/neutral
Rev: 690rpm
Intake: 42kpa steady
MAF 5.0
timing: -16degrees
Any idea what might be causing the rough idle? I did some search on the forum, and looked at what others posted that might be suspect.
The things I haven't checked are
1. the motor mounts (which I think is unlikely in my case, since I would think it would be idling rough both in and out of gear if that were the case)...
2. The MAF/throttle body... The idle is silky smooth in gear, but when in gear, the idle drifts between 550-565 RPM....
Any ideas?
Last edited by fredc888; Oct 23, 2013 at 10:52 PM.
