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Discussion Starter #1
New to me Acadia. Only code I am getting is P0300. 149000 miles. I don't know the history on the car. Will start and run. I drove it 10 miles to my home. Handles nice but runs poorly. It makes a rattle for a few seconds. Misses very hard at idle. I am going to assume this is a timing chain issue from all the other posts and videos I have seen. I just hope there is no bent valves. Seems like I would have other codes if the timing chain had jumped.
 

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Welcome to the forum.
The problem could be as simple as the previous owner never had the spark plugs changed. :unsure:
 

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Discussion Starter #3
I hope to work on it next week. I will pull the plugs and do a compression check . It has a hard miss like I had on a 2001 honda odyssey with a burnt valve.
 

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You'll have the intake plenum (upper manifold) off when you change plugs. That would be a good time to examine the valves (intake at least) with a borescope. Look for excessive carbon deposits. Carbon is easily cleaned from the intake valves, relatively speaking. Carbon deposits are one of the most common causes of misfires in early GDI engines. Misfires will cause an engine to make all kinds of strange noises, too.
 

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Discussion Starter #5 (Edited by Moderator)
You'll have the intake plenum (upper manifold) off when you change plugs. That would be a good time to examine the valves (intake at least) with a borescope. Look for excessive carbon deposits. Carbon is easily cleaned from the intake valves, relatively speaking.
I have a scope. I will take a look.
 

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Discussion Starter #6
The snow slowed me up. I cleaned the snow off the Acadia and hope to pull it in the garage tomorrow.
 

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Aw come on, dude. Working on a vehicle (or anything similar) in the snow, rain, mud, sandstorms, or whatever inclement BS can be thrown your way is a lot of fun!! LOL (been there - done that)
 

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What's a driveway? I spent a lot of my career out in the boonies on remote drilling sites - some of them more remote than anyone could imagine. I pay the price for someone else to do the work on my vehicles, now.
 

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Spark plug electrode on photo's lower right appears wet. It could just be the cycle (part of stroke) when removed, but also could be raw gas from a misfire. Ideally, it should look ashen like the others. Hope you remember the cylinder from where the plug was removed.
 

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Discussion Starter #16
The coil pack on that plug had an X on it. Also, that was the only plug that had oil in the tube. The throttle body appears new, also.
 

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Oil in the spark plug tube makes sense. Hopefully, it isn't too much. Be sure to clean out the tube well before installing the spark plug. The spark plug tubes are press fit and nearly impossible to reseal. It requires a new cylinder head sometimes for a complete repair.
 

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That will certainly make a lot of noise on engine start! Looking forward to know what you plan for the next step. I don't know if it's possible to replace the spring and keeper on this engine with the cylinder head still attached to it.
 

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Discussion Starter #20
I only have $600 dollars in this vehicle. Things are hard to reach under the hood. If I decide to pull the head , am removing the nose on this thing. I am going to think on it tonight.
 
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