2010 2.4l Misfire at Idle


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I have a 2010 2.4l 190K Miles drives and run great down the road. But when at idle is is rough more after it warms up. Using the OBD Torque app on my phone with Bluetooth ODB2 reader. I can see tons of Misfires on cylinder 2 and 3. Also get a P0300 Code.
I have replaced following
Intake & Exhaust Camshaft Position Actuator Solenoid
Ignition Coils
Spark Plugs
O2 sensors (both)
exhaust manifold (Had a Crack)
catalytic converter
New Intake seals
New throttle body seal
New Valve cover gasket

Cleaned MAP sensor
New Air Filter

Checked compression on all cylinders and have good compression
Check Fuel Pressure and that is good also.

Going my scans it mainly misfires at idle.
Could this be a timing chain issue. Checked Chain when I had Valve cover off and did not seem loose at all but I have heard this being an issue.


New member
I was about to make a similar post about my 2013 Equinox w/ the same engine and close to the same mileage. I only have the issue in drive or reverse at idle. If I put it in neutral it's fine. I've had P0303/P0300 kick out. I also keep getting a P0411 that I have to check out (been an issue before the surging issue). I don't think it would be a culprit, but who knows.

When I bought this car it had a busted timing chain guide and it also jumped timing causing it not to start. There was no damage to the engine and I replaced the guides/chains. Aside from that I had to change the intake oil actuator since I was getting codes for it. Everything seemed fine after that for a while. I had some surging earlier but it wasn't this bad, I didn't get codes, and it magically went away for the most part.

I've done my own maintenance for the last 20 years and I would consider myself fairly knowledgeable. With this issue, the first thing that comes to mind is throttle position sensor/idle air control valve. Now with this gen there's only a throttle body and it's drive by wire. I ordered a used TB from ebay just to rule it out. I did a compression test when I initially repaired the timing chains and they were all good. I don't think it's a compression problem. I would rule out spark plugs because I don't have missing while actually driving. If they were going to misfire, they would do it when there is more load and you probably wouldn't notice it at idle. If the coils were bad again you would have a misfire while actually driving too. For the same reasons I don't believe it's fuel related, but that could be a further out there possibility. What I would think it would be aside from the TB is anything that has to do with the system at idle. The pedal position sensor is something I may change, the MAP/MAF would be suspect. It could even be poorly written software that isn't accounting for one of the sensors that is starting to get out of tolerance.

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