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I have a 1998 Nissan Maxima with 90000 miles and i have the problem above. As you can see i did not drive it too much. Just back and forth from home to work and back. I got it used 6 years ago with 35000 miles on it. So for the past 6 years its been running excellent. This year problems began.
I brought it to PEP Boys and they changed the Knocking sensor and charged an arm an a leg. Two days later brought the car back to them for the same problem and they adjusted something and car was OK but the RPM was still fluctuating to while parked. Now as you can see in the video, while the car is parked, it stalls. Driving down the highway, sometimes i am afraid i am going to run into someones bumper because the car revs up. I am planning to bring it back to them since its doing exactly the same thing but just wondering if anyone had this problem and if they solved it.I posted a video online with the problem while car is parked.
[video]http://https://www.youtube.com/watch?v=Uy99BrU7A1I[/video]This video was taken after i drove the car for about 45 minutes. So the car is not cold.
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The first thing I would check is the idle air control valve because of the stalling It could also be a bad mass air flow or even a small vacum leak
To test the iac try unplugging the electrical connecter the idle should drop if nothin happens its bad you can do the same test with the mad sensor but when the mad is unplugged the car should stall right away
[quote=”Ccagno15″ post=73324]To test the iac try unplugging the electrical connector the idle should drop if nothing happens its bad you can do the same test with the mad sensor but when the mad is unplugged the car should stall right away[/quote]
What is a “mad” sensor? Did you intend MAP Manifold Absolute Pressure sensor?
OP, it would be good to know what, if any codes were gotten when the garage worked on it. It also would be good to know what was adjusted. These things are good items to make note of. I wonder if they wrote these items on your work order?
Is it dying because of loosing fuel or spark?
Lol I actually meant maf sensor I apologize I am typing on my phone and D and F are next to each other
The idle valve will show you sign of dirt. I mean, you will ear a lean engine doing bad combustion. To clean the idle valve require a new gasket and a tork wrench to set the fastener to the correct force. A small wrench is require to get inside the engine compartment.
So personally, I will check and clean the mass airflow whit a sensor spray certified cleaner and check the cable below the steering wheel.
why was the knock sensor replaced? is this a stick or auto?
Is the check engine light on or previous codes? Seeing the car
just stalls. Have you changed the fuel filter? I hope pep boys
did not adjust the idle or fast idle adjustment screw.Hello Guys,
Thanks For all the replies. I took it back to PEP Boys and I think i convinced them it can be the mass air flow and they replaced it. I took last night and today i got stuck in traffic for about 2 hours and everything seemed OK. My only worry is that since this problem happens once a day i am hoping that this issue is resolved. I will keep you all updated as time goes by.
The knock sensor was replaced the first time because they said it came back with an error code which pointed to the sensor being bad. The Car is auto and not a stick. They did a whole bunch of tests and everything passed and that what was puzzling them. I have the paper work and i will scan an attach it tomorrow so you all can see what tests they did. To me it all looks Greek but you might have an idea what they did.
I am going to check the ignition just like the video suggests. After they changed the sensor i noticed that the RPMs were still going nuts most of the time so when i brought it back they adjusted the what i am assuming is the air flow using a screw driver. That didn’t fix it.
They tested the IAC and other stuff. According to them everything passed.
I think after this issue i am going to learn a lot about cars.I would be curios on the codes that was read.I take it the
check engine light was on? if you could post any codes that
were pulled that would be great.I doubt it was an ignition switch issue, I doubt even more that the knock sensor had anything to do with it. Knock sensors can retard timing but don’t control engine idle. I would suspect you either had a sticking idle control valve or some other vacuum leak issue. Idle problems are usually mixture problems. In fact, I’ve written an entire article on it.
http://www.ericthecarguy.com/faq/solving-automotive-idle-problems
Keep us posted if things change. It would be great if you could post the codes that were listed. They can help give us a better idea of what was happening.
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