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2011 CTS4 Coupe 3.6
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Discussion Starter #1
I have a 2011 CTS4 Coupe
It has 166,675 Miles. I’m getting Misfire codes for Cylinders 2/4/6. No other codes.
It has new AC Delco Plugs installed about 2,000 miles ago. I’m very certain the coil packs are fine. I got the car with 145,000 miles and haven’t done any Maintenance, nor know of any prior to me owning it. This is my first issue with the car. I change the oil at 50% every time. I don’t hear any noticeable noises coming from the car that shouldn’t be there. So I don’t believe it’s the timing chain, but I could be wrong. Any help with would appreciated. Thank you. I also want to ask the normal PSI at idle. Mine sits under 25. I would assume it would be near 20. In between the first line and under the 25 mark. It’s been like this since I’ve owned the car. But wanted to ask.
 

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Go ahead, blame me. Everybody does 🙄
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Swap the coils with 1,3, and 5 to see if the misfire follows, but with that many miles...
 

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2010 CTS4 sedan
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944 Posts
Well, it's a problem in bank 2. But...

I would run a mode 6 and see if you have misfires in bank 1 as well but they are still below the threshold for codes. The great thing about running the mode 6 is it allows you to track the precise number of misfires you have in each cylinder so if you do anything like swap a COP, you will know for certain if there's an impact of moving the COP. If you don't have a scanner that runs mode 6 reports, I suggest you get one - this is exactly the type of problem they help diagnose.
 

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08 CTS DI
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I don't know Long, one bank of cylinders misfiring all at the same time sounds more like a systemic problem. Is the motor skipping and do you have the ability to check for pending codes? I have had experience with a vehicle that malfunctioned and stalled out before a code was set and indicated by the engine light, however, a pending codes check revealed there was a timing issue and it was later confirmed that there was a timing chain failure. You are definitely in timing chain territory.

Check for vacuum leaks also.
 

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2010 CTS4 sedan
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Yeah, I doubt all 3 COPs would go out coincidentally on one bank but I would check for misfires on bank 1 that might be below the code threshold. I would also run a test of fuel rail pressure, etc. etc.

Timing is the obvious suspect but the lack of timing chain codes is not bringing me there just yet.
 

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Which is why I said " but with that many miles..."
The coil swap is easy and immediately rules them out. I suspect chain failure as well.
 

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I have a 2011 CTS4 Coupe
It has 166,675 Miles. I’m getting Misfire codes for Cylinders 2/4/6. No other codes.
It has new AC Delco Plugs installed about 2,000 miles ago. I’m very certain the coil packs are fine. I got the car with 145,000 miles and haven’t done any Maintenance, nor know of any prior to me owning it. This is my first issue with the car. I change the oil at 50% every time. I don’t hear any noticeable noises coming from the car that shouldn’t be there. So I don’t believe it’s the timing chain, but I could be wrong. Any help with would appreciated. Thank you. I also want to ask the normal PSI at idle. Mine sits under 25. I would assume it would be near 20. In between the first line and under the 25 mark. It’s been like this since I’ve owned the car. But wanted to ask.
You are sure that they are getting spark?
Fuse- 15a even coils?
Otherwise I would have to agree that bad timing would be the most likely cause for 1 Bank to act up.
 

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Yeah, I doubt all 3 COPs would go out coincidentally on one bank but I would check for misfires on bank 1 that might be below the code threshold. I would also run a test of fuel rail pressure, etc. etc.

Timing is the obvious suspect but the lack of timing chain codes is not bringing me there just yet.
I had a p0300 before the MIL illuminated for a p0019 if I recall correctly. There is a way to get a good idea of whether the timing is off. You would be hard pressed to ever get your timing marks aligned but you should always have 10 chain links between the appropriate actuator alignment marks. Left bank uses the circles, right bank uses the triangles. I think the shapes are used by all the manufacturers.
Thats is the entire depth of my knowledge on timing. Good luck
 

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2014 ELR
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All good advice so far. Swap the coils side to side first. While coils are out on that side, pull plugs. Wet from oil? These gaskets/plug tube seals are known to fail, and that can cause a misfire...
 

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2009 CTS 3.6L DI rebuilt to FE3 J55 G80 3.42:1
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I don’t hear any noticeable noises coming from the car that shouldn’t be there. So I don’t believe it’s the timing chain, but I could be wrong. Any help with would appreciated. Thank you.
That is a lot of miles for a timing chain. Mileage alone would, in my opinion, justify replacement if you intend to keep the car. GM extended the wear limits that will trigger a timing chain code to the absolute maximum to reduce warranty costs, so it is possible and likely you'll experience symptoms of wear before the CEL/MIL is triggered. It has been my experience the timing chain code only occurs when the wear is near-catastrophic. It just isn't a reliable indicator, you can have engine problems related to the timing chain without the timing chain code.

It is not my intent to presume to diagnose your problem as a bad timing chain, just alert you that you're well into badly worn territory. Obviously an entire bank of cylinders misfiring is suspicious of something other than a plug or coil. A Tech2 scanner can advise you as to what the actuators are attempting to do, and what your chain wear may be.
 

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2011 CTS4 Coupe 3.6
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Discussion Starter #11
All good advice so far. Swap the coils side to side first. While coils are out on that side, pull plugs. Wet from oil? These gaskets/plug tube seals are known to fail, and that can cause a misfire...
My #6 plug was wet when changed. It was the only one
 

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2010 CTS4 sedan
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Yeah you could have oil leaking into the spark plug tubes but that shouldn't cause codes to be thrown on all three cylinders on one bank. It's not what I would investigate. I also suspect timing but why the absence of P0009? It's why I suggest digging for more data.
 

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2009 CTS 3.6L DI rebuilt to FE3 J55 G80 3.42:1
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I also suspect timing but why the absence of P0009? It's why I suggest digging for more data.
Because the threshold for the timing code was originally set, correctly, by engineers. The software update had the timing chain wear threshold set by accountants, based on postponing warranty claims until the vehicle was out of warranty.

If there is one thing an owner of a 3.6L engine should understand, it is this: The light won't tell you about a timing chain problem until it is really bad and far past when it should have been replaced.
 

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Because the threshold for the timing code was originally set, correctly, by engineers. The software update had the timing chain wear threshold set by accountants, based on postponing warranty claims until the vehicle was out of warranty.

If there is one thing an owner of a 3.6L engine should understand, it is this: The light won't tell you about a timing chain problem until it is really bad and far past when it should have been replaced.
Can't really argue with that.

My experience was that I got the P0008 timing code for bank 1 and had zero evident symptoms. What I hadn't appreciated was that the car's performance had been declining for quite a while but no codes and very very few misfires.

Everybody's symptoms can be different even if the root cause is the same, of course.
 
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