So i installed new Idle Control Valve and Throttle Position Sensor on 2k1 max, but decided to go with current ECU (i had opened the ECU and the STA509A Chip looks good, the rest of board seems fine as well). After starting the car the idle is still high and the P0505 appeared again. I searched the forum but didnt find a procedure to test the ECU if its bad, should i just go ahead and send it for repair anyway?

pic of ECU

 

I think you have the to the "idle relearn" procedure, from several threads I have read.

 

http://forums.maxima.org/5th-generat...1+idle+relearn

 

Sounds like you did what most people do and just replace the IACV without diagnosing it.

I would advise you to go through this:

http://forums.maxima.org/5th-generat...is-thread.html

I replaced my Power steering switch for under $100 and it fixed my IACV code so far.

 

^^^ A must read.

 

ill try the idle relearn next, and then the "P0505>> Definitive Inspection/Diagnosis Thread" what threw me off was that engine check light came back, but from my understanding even if all parts are good (iacv, tps, ecu) but the "idle relearn" is not done it will still trigger p0505 if the idle is to high (in my case 1k and surges to 2.5k when coming to stop and then slowly drops again to 1k). thanks for help.

 

Check out EC-111/EC-116 (with or w/o Consult II) Throttle Position Diagnostic. I had the dealer perform this when the IACV fried the ECM for the 2nd maybe 3rd time and it needed to be re keyed. Also complete the Coolant Bypass sooner than later. Good Luck!

 

Ur Idle is way too high.

You did the diagnositc and it led you to what exactly? Did you fix anything or come up with something? Or are you just assuming stuff

 

from what i read coolant bypass is not recommended for colder winters, i live in STL time to time it gets colder. I need to stop being lazy and read those pages.

 

yeah i assumed that it was iacv from reading the forum about the p0505 code, tomorrow i am going to do the idle relearn and if that doesnt help go by the manual, probably should have done that originally.

 

Not certain what you have read...since doing the coolant bypass I havent seen any degradation in performance and I am in Northern Illinois. However, I have replaced a number of IACV's and each had some coolant on the pins. I suspect expansion plays a part on the failure of the pin and sealant. It's been my experience that electricity and water do not mix and wish I had bypassed sooner than later. Good Luck!