99 Altima

My niece has a 99 Altima with the 2.4L engine. The other day it started having a rough idle which also causes a vibration. She says it kinda goes away when she's driving at it comes back when she comes to a stop. I removed the oil filler cap and you can feel air pulsing out from the opening. I don't recall that being normal(air coming out from the valve cover). I know when sitting in the car in park it almost has the drone like a failing muffler, which was my first thought but the idle is rough for sure.

I read some old posts after searching and it seems that the intake gasket is a common failure, not sure if it applies here though. I was going to try spraying some brake cleaner around the intake but I couldn't really see where to spray...plus I think it's flammable and that's the last thing I need. Any help would be greatly appreciated.

Carb cleaner is really what you should use, as far as the flammability of it.. if your spraying on the intake side your fine..You want to spray around Cyl#4 on the intake side, If idle change is detected.. you know it's the gasket .. GL

Air coming out of the oil filler hole with the cap removed is normal. The motor is overhead cam and they are located under the cap area. make sure you tighten the cap completely because if it loosens you will lose the motor oil real fast.

Ahhh, INTAKE LEAK! I must have read that a dozen times in the searches and for some reasone kept thinking head gasket leak:banghead: I'll pick up some carb cleaner today and try it out.

Thanks for the tip about the air being normal in the vavle cover. Never really delt with OHC engines.

Is it possible for the computer to store soft codes even though the check engine light is not on?

Well, I tried the carb cleaner suggestion and noticed no change in idle. Is there anything else I could try?

The EGR valve should not allow any flow at idle. The valve could be leaking slightly because of carbon holding it open slightly that can be cleaned. Sparkplugs are a possibility. Water gets inside the spark plug tubes and causes miss-fire. Your computer will pick up the miss-fire, store a code, and turn the check eng light on. Maybe the idler pulley for the serpentine belt is wobbling and causing a vibration. Have you driven the car to see first hand what you think? Is it an auto trans?

It is an auto. I haven't driven it myself....probably should now that your mention it. I know she's due to change the plugs and probably her serpentine belt. I'll check the pulley and also the EGR. No check engine light though. Thanks everyone for all the tips.

It is an auto. I haven't driven it myself....probably should now that your mention it. I know she's due to change the plugs and probably her serpentine belt. I'll check the pulley and also the EGR. No check engine light though. Thanks everyone for all the tips.

Did you ever find the rough idle problem?

No, not yet. It's actually getting worse for her. Still no CEL. I just gotta find some time to check further. I'm kinda thinking a pulley also but even removing the belts doesn't look like an easy task.

I replaced my belts and A/C idler pulley bearing yesterday. It was not as difficult as I thought it might be. You do need to raise and support the car and remove the plastic on the passenger side. The bearing is a 203FF. Make sure it has seals on both sides, that is the FF portion of the bearing number. The bearing is easy to change. Use something that will only push on the outside of the bearing and won't damage the seal the push it back into the pulley with a hammer.

I found the issue yesterday. Broken upper motor mount. As I was looking around and was about to start removing the belts, i noticed the rubber on the side of the mount looked as if chunks of rubber was pulled off. Used my pry bar to lift it and sure enough, the vibration disappeared. Seems when it started to fail it caused the vibration and when it finally went out, the engine mount is resting on the bolt causing a little knocking type noise. Thanks everyone for all the input.