[Fishbone36slt2]

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.

 

[speleos]

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

 

[Fishbone36slt2]

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.

 

[speleos]

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.

 

[Fishbone36slt2]

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.

 

[Fishbone36slt2]

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

 

[speleos]

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)

 

[Fishbone36slt2]

I used to work in the driveway. Too old for that now. Florida is calling my name.

 

[speleos]

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.

 

[Fishbone36slt2]

5 minutes into it I found a problem that would make it gutless. Intake tube to throttle body on incorrectly.

 

[Fishbone36slt2]

Fixing that didn't help. Pulled the upper intake , coil packs, plugs, and left valve cover. Curios about what would cause the intake gasket to be wet?

 

[Fishbone36slt2]

Nevermind, that isn't wet. That is gasket sealant.

 

[Fishbone36slt2]

The plugs.

 

[Fishbone36slt2]

Timing chain feels tight on the left head. I will try to check for bent valves tomorrow.

 

[speleos]

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.

 

[Fishbone36slt2]

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.

 

[speleos]

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.