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Jake
Jake, Nissan Technician
Category: Nissan
Satisfied Customers: 4001
Experience:  Experienced collision repair technician, Pulaski Tech graduate and DSM hobbyist.
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Maxima: 2003 nissan maxima 129K, just had fan assembly replaced,

Customer Question

2003 nissan maxima 129K, just had fan assembly replaced, new battery cable and cleaned, revolution sensor replaced, coolant system flushed. When I am sitting at a light in Drive, sounds like there is a puff of air or engine cough and idle drops down. doesn't stall and runs fine while driving. Could there be some air trapped in the coolant lines when it was flushed?
Submitted: 2 years ago.
Category: Nissan
Customer: replied 2 years ago.
It seems to do it after engine has warmed up and does not occur all the time. However, can occur twice while sitting at a red light and other times it doesn't happen at all. RPM needle does not move when idle drops down. RPM is at about 600- 800 while in drive with foot on brake.
Expert:  Jake replied 2 years ago.
Hey there, air in the cooling system won't effect your idle. Generally it will cause overheating at idle that goes away when driving or revving the engine.
Expert:  Jake replied 2 years ago.
I'm not sure I fully understand your symptoms when you say the engine coughs? Is it actually making a noise when it stumbles? Or are you causing the hesitation itself the cough?
Customer: replied 2 years ago.
It sounds more like a puff of air and then the idle seems to drop down however, rpm needle is not moving so I don't think it's anything in the engine. Almost like something is either filling up with air and then releasing or not getting enough air intake.
Customer: replied 2 years ago.
before it does this the idle seems rough and once it makes that noise, then idle seems smoother.
Customer: replied 2 years ago.
does not happen while in park only while brake is depressed in drive.
Customer: replied 2 years ago.
could it be an air intake valve? Never had this problem until I had repairs done I stated above.
Expert:  Jake replied 2 years ago.
Could be the idle adaptations were lost from battery replacement terminal. It's not super common but happens on occasion. The repairs you had should not cause the issues your experiencing unless they removed the intake air box to change the revolution sensor. They could have left a leak on the re installation.
Customer: replied 2 years ago.
Ok I will research the idle adaptations. This makes more sense because I had the revolution sensor replaced about 2 weeks before the battery cable replacement and it didn't start doing it until I had the battery repair, AC cooling fan assembly repair, and coolant flush and power steering flush. All the repairs were done at the same time except for revolution sensor which was done about 2-3 weeks prior.
Expert:  Jake replied 2 years ago.
The idle volume learning procedure is what has to be relearned if adaptations are lost. There is a manual way you can do it without a scan tool as well.
The other thing I noticed is you said the power steering was flushed. If for some reason the power steering pressure sensor was damaged it can prevent the vehicle from accepting the learning.
Customer: replied 2 years ago.
Is there a procedure to follow when unhooking the battery so it won't loose it's KAM. I got this done at my local Nissan dealership so I would think they would have followed proper procedures so as not to lose the KAM. What do you suggest I do - take back to dealer and ask them to reset the idle?
Expert:  Jake replied 2 years ago.
Generally unhooking the battery won't effect it, but every once in awhile it will if the battery is disconnected too long.
If the work was done at the dealer, then it's probably safe to assume they performed the necessary procedures.
Honestly though those were the only issues related to any work that was done, it could be something different altogether, but you sounded like you were concerned that the work may have caused it.
Customer: replied 2 years ago.
only because it started doing that after all the work was performed. I will take back to Nissan and see if it is throwing any kind of code and go from there. I just hope it's not IACV because that is a big expense and I've already spent $1500 in the last month
Expert:  Jake replied 2 years ago.
This year model does not have an IACV, the idle is controlled by the electronic throttle body assembly. When it fails it usually throws a fault code, otherwise it just needs a relearn performed.
Customer: replied 2 years ago.
Just went to a Nissan forum and there is instructions how to perform an idle relearn. Should I try this or let the dealership do it?
Expert:  Jake replied 2 years ago.
Your welcome to try it, just make sure the engine is warmed up and a/c off etc that is in the preset conditions.
You will have to time it pretty good with a stopwatch so you can get the light to flash and know your performing it properly.
Let me know how it goes for you, I can always send you the procedure from the service manual tomorrow if needed.
Customer: replied 2 years ago.
Thank you. Please send procedure from service manual tomorrow.
Expert:  Jake replied 2 years ago.
Here you go