My 2002 Maxima SE automatic developed a habit after a valve cover gasket was replaced. It misfires randomly mainly when the engine is warm. It is noticeable only in idle. After a long drive the misfire is severe and drops the idle rpm to half. There is no check engine light. The dealer cannot find any problem code and returned the car with the same symptoms without doing anything. Two ignition coils had been replaced with Nissan coils about 2K miles ago, the two non-accessible ones. The spark plugs have about 10K miles on them. I am at the end of possibilities... and so apparently the dealer. Somebody mentioned possible dirt in the camshaft control?
Any ideas?

 

Are you sure that the check engine light works? Does it light up when you first turn the key on?

I would suggest that you get a compression check done on the cylinders.

 

The check engine light works when I first start. I also assume that the dealer diagnostics would have detected that. Compression checks should be done, but I hesitate because of the high cost of removing the intake manifold. The general performance of the car, i.e., acceleration and gas mileage is as usual in the past.

 

if its intermittent I would suggest you check your engine harness from the bend near the passenger strut up to each individual coil.

 

Thank you for the tip about checking the harness. I'll request that when I bring the car back to a shop. The misfiring is getting worse and much more frequent (still no check engine light), especially after a longer drive. Idle rpm drops to about 300 when it starts. When I raise the rpm to about 1000 the misfires goes away. I never encounter misfires at higher speeds. I am thoroughly lost....

 

I think it is a coil going bad. You have to wait until it throws a code and then replace the one that is faulty.

 

Theres a video on youtube from EricTheCarGuy about a misfire at idle that smooths out and goes away when you raise the rpms just like you said it turned out to be a air leak and it was a gasket, so could be a hose or bad gasket or bad gasket job look him up

 

Give it some time. It'll pop up.

 

Thanks to all of you!! You are great! The check engine light finally showed up yesterday and indicated that coil 5 was bad. The dealer had checked it about a week ago and found it to be fine.... I hope that will fix the problem...