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Registered
Olds Aurora
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2 Posts
Discussion Starter #1
130K miles
At cold startup idles very smooth. After about 5 minutes it suddenly starts idling rough.

Some history:
Two months ago I got a P0301 code and replaced the rear coil pack, boots, plugs. Car ran fine for 6 weeks.
Front coil pack, boots, plugs were replaced about 50K miles ago.
A year ago I replaced camshaft and crankshaft sensors.

I have replaced the following after the P0300 started.
MAF sensor
MAP sensor
Intake plenum
Intake gaskets
Cleaned Throttle body

Do to the fact that it runs perfect and then very suddenly changes to rough when it warms up, makes me think it is temperature related. I have duplicated this about 8-10 times. Once it is warm it runs poorly at idle and while driving.
Tomorrow I will replace front coil and plugs. I bought them at the same time as rear.

Any ideas?

Tom
 

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Registered
2007 DTS
Joined
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63 Posts
130K miles
At cold startup idles very smooth. After about 5 minutes it suddenly starts idling rough.

Some history:
Two months ago I got a P0301 code and replaced the rear coil pack, boots, plugs. Car ran fine for 6 weeks.
Front coil pack, boots, plugs were replaced about 50K miles ago.
A year ago I replaced camshaft and crankshaft sensors.

I have replaced the following after the P0300 started.
MAF sensor
MAP sensor
Intake plenum
Intake gaskets
Cleaned Throttle body

Do to the fact that it runs perfect and then very suddenly changes to rough when it warms up, makes me think it is temperature related. I have duplicated this about 8-10 times. Once it is warm it runs poorly at idle and while driving.
Tomorrow I will replace front coil and plugs. I bought them at the same time as rear.

Any ideas?

Tom
Mite wana check ECT sensor (engine coolant temperature sensor)
 

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Registered
Olds Aurora
Joined
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2 Posts
Discussion Starter #4
Problem fixed by replacing front coil pack, boots, and spark plugs. The farthest left sparkplug well had quite a bit of oil in the well. Perhaps 2 tablespoons. The next one had maybe a teaspoon. I'm guessing the oil is the real problem and I need to replace the head casket at some time. I kept the coil pack since it might be ok.

Thanks for the replies. This one had me stumped for two weeks.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
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86,781 Posts
The leak is not caused by the HG. It's caused by the O ring seals (#210) in the cam cover.
That said, it is pretty much normal and won't cause a misfire.

 
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