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Jay, Nissan Technician
Category: Nissan
Satisfied Customers: 20386
Experience:  20+yrs experience with Nissan & Infiniti Trained & Certified.Currently still working for Dealer
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2003 Nissan Altima 2.5... car has surging rev... already

Customer Question

2003 Nissan Altima 2.5... car has surging rev... already replaced throttle, pedal, ecu, and IPDM... please help!
Submitted: 4 months ago.
Category: Nissan
Expert:  Jay replied 4 months ago.

Hello my name is ***** ***** thank you for your question.

Did you perform a idle relearn when you replaced the throttle chamber? Also where did you get the part? or should I say Parts?

Customer: replied 4 months ago.
performed idle relearn... parts were pulled from a working vehicle
Expert:  Jay replied 4 months ago.

Do you know if it accepted the relearn? Are you still getting a P0507 code?

Customer: replied 4 months ago.
relearn accepted at least scanner is saying that! I currently have no codes in system... yesterday the car would not go above 2000 rpm and had no rev... now rev is surging and it has power
Expert:  Jay replied 4 months ago.

Did you check for vacuum leaks? I have seen that cause the acceleration issue and also cause the throttle chamber to make the idle go up and down like you are describing.

Customer: replied 4 months ago.
No didn't check for that yet
Expert:  Jay replied 4 months ago.

Then that would be the next thing I would check for. Most common is the intake air duct cracking. I would start there.

Other wise, if you have no Service Engine Soon light on, and no vacuum leaks, you could have a bad MAF sensor. 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 the engine not to 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.

Customer: replied 4 months ago.
Already replaced MAF
Expert:  Jay replied 4 months ago.

Did you replace it with one from your local auto parts store?

Customer: replied 4 months ago.
Expert:  Jay replied 4 months ago.

Perfect! Glad you got it from the dealer. Allot, and I mean allot of people make that mistake when it comes to electrical parts.

So then I would check for the vacuum leaks and monitor air and fuel trim to verify that. When you put the car in gear does the surging stop?

Customer: replied 4 months ago.
Still surges
Expert:  Jay replied 4 months ago.

That may require a Idle Relearn with a scanner if no vacuum leak is detected. But the Throttle Chamber is the only thing that can cause that.

Customer: replied 4 months ago.
I tried to do idle relearn from scanner and it will not complete??? Any ideas
Expert:  Jay replied 4 months ago.

If it does not complete with a scanner, I have seen where power steering pressure switches go bad and stay on, where it can keep the relearn from completing. You need to keep loads off, and engine has to be with in a certain operating temperature when performing the relearn. Some times simply just unplugging the steering pressure switch will work as well.