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Old 02-27-2007, 11:49 AM   #1
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Default GXP misfiring

Hey y'all. This morning when I was leaving for work I noticed, at idle, a considerable misfire in the GXP. After a 50 mile drive to work the car was idling fine. I plan to take it to the shop this evening but first wanted to see if anyone here might have some ideas as to what it could be.
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Old 02-28-2007, 11:22 AM   #2
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Since my car was new, it doesnt like to run well when cold. even when it'* warmer outside it can sputter when I get on it cold. I also have to get on it to "clear it out after I let it sit at an idle for periods of like a half hour whibh is unavoidable when I have my Aunt with me like when I shop and it'* cold outside. Also,... are you running regular fuel. The Northstar really wants better octane with higher than normal compression and this would be more apparent in cold weather.
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Old 02-28-2007, 11:42 AM   #3
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Also,... are you running regular fuel. The Northstar really wants better octane with higher than normal compression and this would be more apparent in cold weather.
Not that I am trying to diagnose your problem on-line, nor am I suggesting that this is your problem, but my 04 GXP really b!tched and moaned (slow starts on cold days)when I accidentally put a full tank of regular in it. I don't think it misfired but my fuel econ went down to 14 city and took two tanks of premo to get back in the 19/20 range, city.
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Old 02-28-2007, 01:02 PM   #4
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I have used nothing but 93 Octance in the car since I bought it new. Actually, I have never used any less in any of my cars.

However, I found out this morning that the fuel station I always use had a problem with one of their storage tanks and will be closed for a few days. Could be something to do with it.

I filled it this morning at a different station and by the time I got to work it was back to its normal self.

Hopefully this works.

Thks.
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Old 02-28-2007, 02:18 PM   #5
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the fuel station I always use had a problem with one of their storage tanks
Be very wary of fuel stations with old tanks. Who knows what got into your gas? Water? Rodents? Jimmy Hoffa? I completely avoid stations with old tanks (e.g. old gas stations).
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Old 02-28-2007, 02:33 PM   #6
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I jsut went outside and let the car idle for about five minutes and it ran very normal without misfiring.

The fuel station I normally use is very old. I filled up this morning at a very new chevron station. Like you said, could have been anything in the gas...
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Old 02-28-2007, 03:07 PM   #7
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My 18k mile 05 GXP does, for lack of a better word, occasionally “shake” a little for 5 - 10 seconds or so when I first start it up. Nothing major, but you can feel that the engine is not quite running smoothly. I don’t think I’ve noticed it happening on a cold start first thing in the am, but maybe if the car has been sitting for an hour or 2.

I run nothing but 93 octane. If anything, I believe higher octane fuel would contribute to the problem on a cold or cool start since it burns more slowly and is slightly harder to ignite than the low octane stuff.
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Old 03-23-2007, 09:34 AM   #8
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Finally figured out the problem with the misfire. Turns out that the coil for #5 cylinder was starting to fail and subsequently caused a misfire at low rpm. It took the dealer nearly 5 days to figure this out. Got the car back last night and I am happy to say that the car is back to normal.

Well at least I got new plugs and new injectors for free.
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Old 03-31-2007, 12:03 PM   #9
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It was missing with out any codes ?
odd isnt it
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