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2007 9-3 Combi with 2.0 engine. 61,000 miles.
Issue – rough idle after cold start in morning.
Details:
Cold start in morning after sitting overnight.
Extremely rough, loping idle.
RPMs rise and fall to point of almost stalling then it’s as if the engine ‘catches’ and RPMs rise for a second or two but then cycle continues.
Chugging sound from exhaust and sometimes 1 or 2 mild pops like backfire.
After 20-40 seconds idle smooths out and all is well for rest of day.
Other info:
Worse the colder weather but can occur even if ambient temp is in the 70s.
Appears to be a ‘sweat spot’ in the ambient temp (low 60s?) where does not happen.
Has been occurring for last few years and getting progressively worse to the point it needs to be corrected before winter sets in here in Colorado.
Can slowly press gas pedal and eventually RPMs will rise but once remove foot rough idle returns.
What’s been done by Indy:
Compression check when cold – 180-190-190-175
Checked plugs and gap – OK (replaced at 45,000 miles)
Checked misfire counts 631-435-421-669
Performed ‘top engine clean to decarbon’.
Said it started fine next morning when ambient temp should have caused issue. But has occurred for me last several days.
Current plan:
Told Indy issue not fixed and they wanted me to bring it in but had no idea of what else could be causing the problem. And since they only get one shot a day at diagnosing the issue, it could take quite a while to find something. So I am recording sound and video of tach after starting to show Indy what is happening and perhaps it will give then an idea of how to proceed.
My thoughts:
Thought it might be the valve issue but compression check seems to indicate not. Fact that has gotten progressively worse tends to rule out items that fail all at once such as many electrical components. Low fuel pressure? But why not issues other than at first cold start and only for less than a minute?
Any ideas?
posted by 71.218....
, Wed, 5 Oct 2016 07:51:18
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