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Mike V.
Mike V., Nissan Technician
Category: Nissan
Satisfied Customers: 25331
Experience:  Nissan factory trained and Certified Subaru Technician.
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Jay I was chaging the spark plugs on a 350z yesterday and I

Customer Question

hi jay I was chaging the spark plugs on a 350z yesterday and I cleaned the throttle body out while I was at it and then when I had everything done an went to start it I idles high then drops from 2000-1000-2000-1000 an so on what do I do ?
Submitted: 1 year ago.
Category: Nissan
Expert:  Mike V. replied 1 year ago.

Hi there,

Did you remove the throttle body or intake when doing the work?

Possibly disconnect the battery?

Customer: replied 1 year ago.
I did while I was working on it and I've already done a few other tricks that I've read online like the Ecu relearn disconnecting two spark plugs a whole lot
Expert:  Mike V. replied 1 year ago.

You disconnected 2 injectors and then did the relearn?

Customer: replied 1 year ago.
Correct while it ran I disconnect two injector an then did the relearn
Expert:  Mike V. replied 1 year ago.


next step is to check for any intake leaks. With it running spray some carb cleaner along the intake and see if the idle smooths out. Sometimes if they are searching it's due to vacuum leaks. If none are found, try unplugging the mass air flow sensor and starting the car. If the idle smooths out, it may be an issue with the maf sensor. Finally, if none of that proves to be the issue, then the throttle body likely got damaged during the cleaning and will need to be replaced. They aren't supposed to be cleaned as the varnish can get into the motors and mess em up.

Customer: replied 1 year ago.
Because last night after this happened I took the car to auto zone to read the code and it came up as something about the Throttle body and nothing about the MAF
Expert:  Mike V. replied 1 year ago.

What was the code?
If it was P0507 that just means the idle is messed up, which you know already of course.

Customer: replied 1 year ago.
Yea but can the MAFs be bad even if they didn't come up in the reading ?
Expert:  Mike V. replied 1 year ago.

Yes, if it's reading wrong then there won't be a code. The computer will just adjust to whatever the maf is telling it. I am not saying it deff the maf sensor, but, if the idle stabilizes with it unplugged, then it's the likely culprit. You will see when you unplug it, the check engine light will come on and give you a maf code. This is because the computer will not see any info from it. That's when it says "OK, we have a problem" Otherwise it's not smart enough to know it's out of range and will just keep trying to make the right adjustment to the fuel.

Customer: replied 1 year ago.
Ok I started it up with out the mafs and it still idles the same 2000-1000
Expert:  Mike V. replied 1 year ago.

Ok, that tells me the maf is fine, so check it for the vacuum leaks, if that doesn't work then I am afraid you might need the throttle body. Since the manual relearn didn't work, you might want to have it done with a scan tool before you replace the throttle body.

Customer: replied 1 year ago.
Scan tool? Like at a auto zone?
Expert:  Mike V. replied 1 year ago.

No, AUtozone only has a code reader. A scan tool needs to be used. Either the dealer or contact a couple shops to see if theirs is capable of doing the throttle relearn.

Customer: replied 1 year ago.
An they will determine if the Throttle body's are truly going to need replacing ?
Expert:  Mike V. replied 1 year ago.

Yes, because if it won't take a relearn via the computer and scan tool, then it will be the problem. There is some room for error when you try to do it manually. This will eliminate that possibility.

Please let me know what more I can do to assist you today. Also, please remember to rate my answer, Just Answer does not compensate me for my time and resources. Follow up questions are included in the price of your question. If you are using the free trial, a rating is still required.
Thank you so much!