[colman]

Experiencing rough cold start. AFR on bank 1 typically does not reach 234 when letting off the throttle. No misfire codes since a few months ago where I had a misfire on cylinder 1 at both cold start and idle on two separate occasions. Haven't had any misfire codes since replacing plugs 4K miles ago.

Pulled 1-3 plugs (4K miles old) after sitting all night

Plug 1 is quite clean but smells of fuel.

Plug 2 is pretty clean.

Plug 3 threads are black and oily.

When I replaced the plugs 4K miles ago I noticed that the oil cap had been leaking slightly and there was some oil by the 2&3 plug holes. I have recently changed the oil cap.

On the old plugs there was a lot of oil on the plug 3 threads

So, bad fuel injector on cyl 1 and a bad valve cover/gasket causing the buildup on plug 3? I think a fuel injector leak is quite obvious but would love any feedback!

Thanks!

[Soden82]

I had similar experiences. I had a leaking valve cover with a hairline crack by plug 2 and 3, as well as a brittle leaking gasket by 5 and 6.

I replaced those, and have had persistent cold start misfires on cylinder 6. Pulled the plugs and could not tell a fuel smell due to how much oil was on the plug from the leaking valve cover and gasket.

I'm doing the injectors tomorrow or next weekend to try to get rid of the cold start misfires.

What you could do is when you replace the VC and or gasket, pull out all the spark plugs, clean them up, and let the residual oil that leaked out go down into the spark plug holes to be burned off when you start the car again.

Or do your best to clean around the area with a rag or towel after valve cover removal

[colman]

Originally Posted by Soden82

I had similar experiences. I had a leaking valve cover with a hairline crack by plug 2 and 3, as well as a brittle leaking gasket by 5 and 6.

I replaced those, and have had persistent cold start misfires on cylinder 6. Pulled the plugs and could not tell a fuel smell due to how much oil was on the plug from the leaking valve cover and gasket.

I'm doing the injectors tomorrow or next weekend to try to get rid of the cold start misfires.

What you could do is when you replace the VC and or gasket, pull out all the spark plugs, clean them up, and let the residual oil that leaked out go down into the spark plug holes to be burned off when you start the car again.

Or do your best to clean around the area with a rag or towel after valve cover removal

Did you have any luck after replacing injectors?

[Soden82]

Originally Posted by colman

Did you have any luck after replacing injectors?

Yes and no. It did not solve my cold start misfires. I'm borrowing my friends autel mx808 to check voltage to my o2 sensors to try to rule those out.

Injectors did help a lot in terms of driveability. Acceleration feels smooth with any throttle input now and my car feels less hesitant when I put the throttle down.

[alpnwss]

If you can check your fuel trims that will tell you if injectors are screwy. But if you've already replaced, this is a little redundant.