Ghost in the Machine
#1
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Ghost in the Machine
So...mid-last week, upon cold startup (sitting in parking lot at work all day - temps in 20's or 30's if I remember right) - the engine was running rough. I could hear audible miss'. On the drive - even after full warm-up - I noticed 2 things: 1) it felt down on power needing downshifts for 'normal' acceleration. 2) strange rpm bounce. Low-speed coasting, I would catch the tach bounce off of @500rpm (or there-about) and return to 'normal'. This would occur when doing about 30-40mph and I would take my foot off of the accelerator.
Only thing I did over the weekend was fill-up the tank. In addition - under the guise that maybe I had some bad gas (no beano jokes please!) - I added a bottle of Gumout 'complete fuel system cleaner'. I normally do not use those things, but figured what the heck.
OK - so after 2 days of driving it - the situation seems to be completely gone. I DID hear a miss on cold start this evening. But engine response has returned to normal - and the strange rpm drop upon 'coasting' has vanished. Last week that was easily repeatable - tonight...not at all.
So my question is - What the heck? Any thoughts?
Note - no codes where thrown - no CEL - no nuttin!
Only thing I did over the weekend was fill-up the tank. In addition - under the guise that maybe I had some bad gas (no beano jokes please!) - I added a bottle of Gumout 'complete fuel system cleaner'. I normally do not use those things, but figured what the heck.
OK - so after 2 days of driving it - the situation seems to be completely gone. I DID hear a miss on cold start this evening. But engine response has returned to normal - and the strange rpm drop upon 'coasting' has vanished. Last week that was easily repeatable - tonight...not at all.
So my question is - What the heck? Any thoughts?
Note - no codes where thrown - no CEL - no nuttin!
#3
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Thread Starter
The RPM drop/bounce was a more curious side-effect of whatever the issue was - more-so than anything else.
Time will tell if it goes away and stays away.
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MalbecG37S (01-14-2015)
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#8
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#9
So...mid-last week, upon cold startup (sitting in parking lot at work all day - temps in 20's or 30's if I remember right) - the engine was running rough. I could hear audible miss'. On the drive - even after full warm-up - I noticed 2 things: 1) it felt down on power needing downshifts for 'normal' acceleration. 2) strange rpm bounce. Low-speed coasting, I would catch the tach bounce off of @500rpm (or there-about) and return to 'normal'. This would occur when doing about 30-40mph and I would take my foot off of the accelerator.
Only thing I did over the weekend was fill-up the tank. In addition - under the guise that maybe I had some bad gas (no beano jokes please!) - I added a bottle of Gumout 'complete fuel system cleaner'. I normally do not use those things, but figured what the heck.
OK - so after 2 days of driving it - the situation seems to be completely gone. I DID hear a miss on cold start this evening. But engine response has returned to normal - and the strange rpm drop upon 'coasting' has vanished. Last week that was easily repeatable - tonight...not at all.
So my question is - What the heck? Any thoughts?
Note - no codes where thrown - no CEL - no nuttin!
Only thing I did over the weekend was fill-up the tank. In addition - under the guise that maybe I had some bad gas (no beano jokes please!) - I added a bottle of Gumout 'complete fuel system cleaner'. I normally do not use those things, but figured what the heck.
OK - so after 2 days of driving it - the situation seems to be completely gone. I DID hear a miss on cold start this evening. But engine response has returned to normal - and the strange rpm drop upon 'coasting' has vanished. Last week that was easily repeatable - tonight...not at all.
So my question is - What the heck? Any thoughts?
Note - no codes where thrown - no CEL - no nuttin!
#10
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Thread Starter
I'm experiencing this same issue. The car is rough and loud in cold weather, but the problem will clear up after driving 5 to 6 miles. The colder the rougher and louder. Definitely seems to be directly related to cold weather. The loud and rough is way more than the normal loudness of this car. Sometimes I get a smell of burning plastic right before things start to smooth out. The smell is not noticeable under the hood. Initially thought it was an exhaust problem, but the problem seems to be something that affects exhaust harmonics vs. a leak. Thought it cold be bad gas, but I use nothing but top tier brands and the issue has remained for several tankfuls. Any thoughts?
I can't explain the smell of burning plastic - I can say that I smelled a significant amount of unburned gas when my situation persisted.
Could always try a fuel system cleaner (Gumout), etc - see if they have any effect.
Let us know - thanks
Last edited by MalbecG37S; 01-25-2015 at 08:53 PM.
#11
Using top tier gas does not mean you couldn't get a bad tankful...
I can't explain the smell of burning plastic - I can say that I smelled a significant amount of unburned gas when my situation persisted.
Could always try a fuel system cleaner (Gumout), etc - see if they have any effect.
Let us know - thanks
I can't explain the smell of burning plastic - I can say that I smelled a significant amount of unburned gas when my situation persisted.
Could always try a fuel system cleaner (Gumout), etc - see if they have any effect.
Let us know - thanks
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