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Jay
Jay, Nissan Technician
Category: Nissan
Satisfied Customers: 18891
Experience:  20+yrs experience with Nissan & Infiniti Trained & Certified.Currently still working for Dealer
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My Murano suddenly started stalling and idling rough. It now

Resolved Question:

My Murano suddenly started stalling and idling rough. It now won't even stay running, even in park and my foot on the gas. Vacuum leak? TPS? Fuel filter?
Submitted: 6 years ago.
Category: Nissan
Expert:  Jay replied 6 years ago.

Jay :

Hello and thank you for using JustAnswer.com

Jay :

When the vehicle is running, is there a Service Engine Soon light on?

JACUSTOMER-7udcdpad- : I didn't see one. I was panicking in traffic at the time, and iy ddn't seem to be lit when I tried it when I got home, but itbwas running really badly by them,
Jay :

Does it it idle poor also?

JACUSTOMER-7udcdpad- : Sorry about the horrible typing, I'm my Ipod. It was idling slightly bad about a mile from home, at a light. I put it in neutral and brought up the revs. Seemed to work for a while, then it seem to get worse where it wouldn't even bring up the revs.
Jay :

Are you able to do a quick test?

JACUSTOMER-7udcdpad- : Hmm, I'm not near the car, but I could run out there, yes.
Jay :

Open the hood, and unplug the MAF sensor. Then get in the car and start it. Let it idle, and don't give it gas. Just see if it runs smoother.

Jay :

Do you know what the MAF ( Mass Air Flow ) sensor is and where it's located?

JACUSTOMER-7udcdpad- : I'm sorry to say I don't. I'm an engineer and have done some car repair, but not on this vehicle, and only specific things like o2 and brakes, etc. Give me a hint.
Jay :

Ok

Jay :

Where the air filter goes

Jay :

The MAF sensor attaches to that part of the air box.

Jay :

Got it?

JACUSTOMER-7udcdpad- : I think so. Grabbing a jacket and heading out. Should have reception out there. Take a minute or two.
Jay :

k

JACUSTOMER-7udcdpad- : 5 pin connector between air filter and engine?
JACUSTOMER-7udcdpad- : Started right up, service engine soon light on.
Jay :

I know the light will come on, but how does it run?

Jay :

or idle I should say?

Jay :

Better?

JACUSTOMER-7udcdpad- : Plugged back in, still idling great.
Jay :

So it ran better?

JACUSTOMER-7udcdpad- : Now it's wavering in revs a bit. Sensor plugged in. Unplugging again.
Jay :

If you unplug it with the car running, it will stall

Jay :

What I am trying to determine is if the truck idles better with it unplugged, or plugged in?

Jay :

Don't give it gas, just let it idle.

JACUSTOMER-7udcdpad- : Not giving it gas. Idling well without sensor plugged in. It idles between 1k and 1300, fairly normal.
Jay :

Ok

Jay :

That Service Engine light wasn't on till I had you unplug the MAF sensor right?

JACUSTOMER-7udcdpad- : I believe that is correct, I don't remember seeing it.
Jay :

ok, Most likely the Problem is the MAF sensor. Unplugging it will cause that light to come on, but it's a effective test.

JACUSTOMER-7udcdpad- : I see.
Jay :

To clear the light, just disconnect the negative battery cable for 10 mins

Jay :

90% of the time the MAF ( Mass Air Flow ) sensor heated element which meters the air so the computer can add the proper fuel mixture has fallen out of spec. Not enough to cause a Service Engine Soon light but enough to cause the Air and fuel Mixture to be so off it can cause Stalling, poor acceleration, won't rev over a certain Rpm, and running issues. I would have the Air and Fuel mixture readings checked to verify. Checking the voltage will not show the fault, the air and fuel mixture will. If found to be bad, do not replace with a After Market one. After market MAF sensors never seem to work properly. There heated element doesn't work right which can cause 02 sensors to flat line and have you chasing you tail trying to figure out what is wrong. So the only way to correct this issue if you do have a bad MAF sensor is to replace it with a OEM.

Jay :

If you have any more questions on this, please feel free to ask. Thanks Jay!

JACUSTOMER-7udcdpad- : Wow, that sounds like good info! Can I run the vehicle enough to get to the parts counter, and it looks somple to replace muself. Is it?
Jay :

yeah, it's easy to replace. If your Maf has totally fallen out of spec it may be dangerous to drive

Jay :

I would also recommend you stick with the Nissan MAF, not the After market ones.

JACUSTOMER-7udcdpad- : I'm a better mechanic than a typist...I'll head to the Nissan dealer directly in the morning, once I make sure they have one.
Jay :

I am sure they do

Jay :

Don't get alarmed, I am giving you the heads up

Jay :

The factory MAF sensor is expensive cause of the type of material used for the heating elements.

Jay :

After market don't use the same material, and that is why they are much cheaper, and that is why they never work right.

Jay :

I know how you engineers are. You like to know stuff like that.

Jay :

hehe

JACUSTOMER-7udcdpad- : Lol yes. I design and built radar systems. I understand using the correct materials.
Jay :

I would have the truck checked to verify though.

Jay :

Because the part is expensive, You would want to verify this.

JACUSTOMER-7udcdpad- : Understood. How expensive, ballpark number?
Jay :

around 3 to 4 hundred

Jay :

Where the after market is around 90 bucks. So think about it, 300 to 400 vs 90 bucks. There is a reason why that part is so cheap. Keep that in mind.

JACUSTOMER-7udcdpad- : Gotcha. Not a problem. Maybe I'll have a mechanic check it out, then insist on the OEM part if that is indeed the issue.
Jay :

You got it. If you have any more questions on this, please feel free to ask. Thanks Jay!

JACUSTOMER-7udcdpad- : Thanks! This was very educational and worth the money. I like this process. I'll sleep better!
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