So, 2002 pathfinder with 0505 code.

Car surges and until it dies at idle, going from 1000rpm to 2000 and back down, revving over and over and it stalls sometimes. Tried to change the iacv, had some problems (thank you to all from the previous post). It was a junkyard iacv. I tested it at home in my shop, the resistance was all good, even though it completely killed the car and didn't even let it idle.

Since it wouldn't idle, I couldn't do any of the relearns because I couldn't drive it, (trans was cold, wasn't all the way at operating temp, etc). Should I buy a new one and mess with the iacv again, despite the good resistance reading on the "bad" one? Or now that it's "idling" somewhat should I meet the relearn conditions and try doing those to see if that will fix my issues? I fail to see how a relearn procedure could fix this issue. Based on the problems, could it even be the iacv? Or could it be something else? Heard 02 sensors and MAFS can cause p0505.

Thanks for listening.

Update: Just ordered an OBD2. I work on old chevys and nothing newer than 1980 mostly. Bout time I got an OBD Reader. Going to read the codes and diagnose further, read that a bad icav can kill the ecm and just a compound of other issues. Wish me luck

Correct, a new but good IACV/ECU will result in a high idle as opposed to no idle.

Most likely your bad IACV fried the ECU. Find an ECU repair vendor on eBay, and replace your IACV with a new Hitachi. Dont put an old IACV in with a repaired ECU, for risk of frying it again.

You can do some Googling to see what a fried ECU looks like, then open yours up to see if that is the case.

How many miles do these go out typically?
My pathfinder was idling funny the other day but has since returned to normal. My pathfinder is at 243k miles I’m kinda curious if I should do this as a preventative fix.

It seems to be a very common issue. Mine went out without warning at around 200k.

These things are now 18 years old, so no surprise that they are failing. At 243k miles, I wouldn't wait.
I'd bite the bullet and replace the IACV with a new one (not rebuilt or junk yard unit).
I went through this a few years ago and it was not a pleasant experience.

https://imgur.com/gallery/SGRVaC4

I could smell it.

Chip and valve on the way. Luckily I’m pretty good with a soldering iron. Any thing I need to be aware of considering the order in which this job is done? Unplug battery? Unplug iacv or ecm first? Or does it even matter when the key is off? I just know both need to be changed.

Doesn't matter.

rgk wrote: ↑

Sun Jul 26, 2020 7:04 am

Doesn't matter.

Thank you!

Replace the gasket between the IACV assembly and the throttle body. Alot of the time that gasket fails and leaks coolant onto the IACV causing it to short and fry the ECM.