2002 G20 idle problem -ECU?

[Finselba]

Hello. I just bought my first nissan (infiniti) today. It is a 02 G20, but it has one "issue" that I need some guidance on. The former owner just had it inspected (passed), but then idle issues started. He replaced the IAC, but this did not fix it. To make a long story short, the dealer claims that the ECU needs to be replaced. So I am the proud owner of nice car (120K), and I need to know what I can do to adequately fix this problem without breaking the bank. Some indicators: starts, but stalls at idle unless extra throttle is given. The CEL is P0505 IAC. A new IAC was just installed.
1. Should I trust the dealer assessment of the ECU (can I independently confirm this?) what troubleshooting should i undertake?
2. Can I purchase and installed a used ECU?
3. is there anything specific that requires the dealer's service if I installed the ecu?
4. How involved is it to access the ECU -i know it is in the middle of the center of the dash
-is this a simple task (behind cd player) or does the entire dash gave to come out?
5. has anyone tried to have their ecu repaired?
6. any general thoughts on this? Is this a common problem?
7. what does relearning mean? and how do you do it?

I would be grateful for any insight that anyone could offer. I dont want to pay the $1500 that the dealer is asking for if it can be avoided. Thank you for taking the time to look at my post.

Alex

[Finselba]

I got the ECU repaired and the car now runs. However, the idle is high (1100-1500RPM) and I have the lovely P0505 CEL. I have heard that I will need to reset the base idle or do idle learning, but am unsure of how to do this. I am also curious if anything else may cause this issue. I dont want to goto the dealer if possible. Any suggestions?

[RED_DET]

You can try the idle relearn procedure set forth here and see if it works:

-Warm up engine.
-Turn ignition switch OFF and wait at least 10 seconds.
-Confirm that accelerator pedal is fully released, turn ignition switch ON and wait 3 seconds.
-Repeat the following procedure quickly five times within 5 seconds.
a. Fully depress the accelerator pedal.
b. Fully release the accelerator pedal.
-Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the MIL stops
blinking and turned ON.
-Fully release the accelerator pedal within 3 seconds after the MIL goes ON.
-Start engine and let it idle.
-Wait 20 seconds.

[Finselba]

I will try this procedure, but will this work for the G20? I have read about a different idle relearn which involves disconnecting the brown TPS sensor. Just thought I would ask.

[vk45de]

That procedure didn't work for my 02

I found this in the FSM - that's after you drive car around for 10 minutes and park car in N or P with wheel pointed straight ahead.

[rednessand]

Has this issue been resolved? I replaced my idle control valve because of no idle. The idle control valve had a broken solenoid so I replaced it. I had no code, but now that I replaced it, my idle is high and I have a code to replace my idle control valve.

[B13_Red]

rednessand,
Is the throttle body plate/valve open more than it should be? Strange to have that fault code after replacing the defective IACV.