Sometimes when my car is running in neutral, it will not idle at around 700 rpm - it will steadily cycle from 300 to 800 rpm back to 300 (approximately), and not stay at one idle speed. The thing about this that confuses me is that it does this some of the time. I think this may be related to another problem I'm having: when I get above 3 - 3.5k rpm, the engine misses or something like that. For instance, I'll be going around 75 mph down the highway, then the engine feels like it loses power, starts to feel like it's running a little rough, so I punch the accelerator and it will stop until I let cruise control take back over. Again, this is a problem that occurs every now and then. I originally thought that perhaps it was the fuel filter, so I changed it out. I'm thinking about changing the spark plugs out soon, too, I'm not sure how old they are, or if it would even solve my problem. Or, could it be a vacuum leak? Any help would be appreciated, thanks.

yeah, my car does that too

i replaced the fuel filter and the spark plugs and it does what you described above, sometimes

not sure what it is, i think i may have a dealer check it out or something

MAF. I just went through that same problem and about $300. I tried plugs, fuel filter and pump, wires, rotor and cap, o2 sensor, and even timing. But the instance I replaced the MAF, it was fine. Just check your plugs and o2 sensor before you start it with the new one. They may be fouled out.

noob question... what and where is the MAF?

The MAF (Mass Air Flow Sensor) is located right behind your air filter it measures the air entering the intake tract is used to determine the amount of fuel your engine needs.

oh, thought so

does anyone know where i could get an MAF and how much

possible instructions of how to replace it would be awesome too :)

I bought mine from Autozone and it was $265. It is a python injection one. You can get them from the dealer too. Just look at the MAF and you'll see how to replace it. It will take about 4min and 35sec if you get what i mean.

do you think if i have the dealer install it that it would be really expensive?

(including the cost of the MAF)

That would be wasted money. The hardest thing you will have to do is take a c clip off the wire harness. You will need a flat edge, a 10mm, and five minutes.

did your car used to do the crazy rev thing then stall out and die before you changed the MAF?

mine does, ususally when it's going up hill

my coup does the same thing. But on mine if quite predicatable - usually, I put it some injector cleaner and it would clear up after awhile. It also happens if there is a leak on exhaust or intake. Other possibilities are Air Idle controller, bad alternator ( but the lights would dim), bad fuel pump ... there are lots of possibilities.. including faulty wirings

Try injectors cleaners first because its the cheapest otherwise you will start changing parts one a t time and can cost quite a bit. check ecu codes if you can

This really does seem like a common problem. My car has the same problem but at around 2,500 rpm. Any time the turbo is spooled car drives great but if it is at idle like I come to a red light put it in nutral and just slow down with the brake it goes down to like 100rpm (sometimes dies) then up to 800 then to like 200 and back to 800 and does that pattern like 1 or 2 more times then settles at 800 and idles smooth just feels like it's missing every once in a while at idle and the car also boggs down at around 2,500 rpm when crusing and if I don't give it any gas it keeps on bogging but the second I give it gas car quits doing it so I find myself accelerating everywhere I go :)

same... i have idle problems similar to this too. Is there a way to verify that it definitely IS the MAF? if so i wouldn't have to go thru the plugs, wires, rotor/cap and 02 sensor...

Had the same problem in the Altima, but after the rotor, cap, plugs, wires, it stopped.

Had the same problem in the Altima, but after the rotor, cap, plugs, wires, it stopped.

oh sounds good. i'm on it then. haha...

Umm this thread is a year guys. desimontreal start a new thread next time instead of reviving a year old thread. ;)