uneven running at cruising speeds
03-01-2013, 10:53 PM
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uneven running at cruising speeds
My 2000 C2 Tip with 55,000kms is running unevenly at normal cruising speeds. It doesn't appear to be missing, just a slight hesitation or variation. It will occasionally run rough at cold start up, but is fine almost immediately and accelerates with no hesitation......any thoughts as to a likely culprit? My searches so far haven't had much success......
Cheers Bryan W ......Darwin Australia
Cheers Bryan W ......Darwin Australia
03-02-2013, 01:33 AM
#2
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My 2000 C2 Tip with 55,000kms is running unevenly at normal cruising speeds. It doesn't appear to be missing, just a slight hesitation or variation. It will occasionally run rough at cold start up, but is fine almost immediately and accelerates with no hesitation......any thoughts as to a likely culprit? My searches so far haven't had much success......
Cheers Bryan W ......Darwin Australia
Cheers Bryan W ......Darwin Australia
Well there's the AOS. With the engine warmed up and idling in Park can you unscrew and remove the oil filler tube cap? If not or if it is difficult this is a sign the AOS is going out. If you have no trouble removing the cap this is not conclusive proof the AOS is ok though.
If you want disconnect the MAF at the wiring harness and ideally with an OBD2 code reader clear the codes to reset the fuel trims to their defaults.
Then drive the car as you have been when the symptoms appeared before.
If the symptoms are not present then reconnect the MAF, clear the codes again, and driver the car again to make sure the symptoms return.
If the symptoms do not go away the problem lies elsewhere. See AOS.
But it could be a fuel filter. A failing fuel pump. Bad gas. Or something deeper though the symptoms do not strongly point to this.
03-02-2013, 10:28 PM
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car looks like its only had annual servicing to date with no issues.....I'm a relative newbie to the car having owned 928s before. Will do some research on AOS threads and acquire an OBD2 reader....any recommendations? I was thinking of replacing MAF as they appear cheap but don't even know whether my car is E gas or not at this stage
03-04-2013, 08:38 AM
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OBD2 reader is ordered. I can remove the oil cap without difficulty at idle....reasonably strong vac/suction noise and revs jump about 200rpm, falling back to 600ish when the cap is replaced. Gas is fresh. Thelocal OPC / dealer disturbed something at the last service leading to rough idle (wasn't us - we didn't touch that) but they sorted the problem and I don't know what they did.
04-22-2013, 09:33 AM
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uneven running at cruising speeds - happy ending
Replacement of the (suspected) MAF sensor has totally cured the problem...cheap and easy fix on this occasion. .....and haven't even got to play with new OBD2 reader yet. Thanks to respondents
