P0505, IACV Issues and Solution

[RedRider3141]

So, there I was towing a 4x8 Utility trailer mounded with topsoil and my '01 just up and dies as I round the corner into my neighborhood. Odd? Whatev, Kickit into neutral and start it back up while I'm still rolling. Pull up to my house to back in the trailer. Bleh, it dies again. This goes on a few times as I feather the throttle and brake just to get the thing in the driveway. Lots of fun with some weight behind it. The car will NOT idle, revvs to the moon just fine but will not idle.

 

All through this not a single SES light. I begin to search around and I find many "Solutions' but most everything points back to the IACV which controls the idle.I tried a few "Cheap" Solutions: I needed an air filter, so I did that. I hadn't ever cleaned the MAF in the 35K i'd owned it so I did that. After a few test drives nothing. I even tried the Idle Air Relearn proceedure in the Service manual but got nowhere. Then finally after a few days of testing I got the SES. I scanned it and got P0505.

 

Well in my internet sleuthing I had read about the horror stories of the IACV circuit blowing in the ECM and decided to park it and not mess with it more. I really didn't know if it was too late or not but I didn't want to push it. I ended up ordering the IACV from Parts Geek along with the Throttle Body Gasket and IACV gasket. I paid an arm and a leg for shipping but the grand total was ~$120 which was anywhere from $50-$130 cheaper than Amazon, Rock Auto, Napa, Courtesy Nissan Parts, etc. AND it was the only place I found a Hitatchi brand IACV, Felpro Throttle Body Gasket and Nissan IACV Gasket. Which was my #1 or #2 brand of parts for each of those items. It took about a week for all three parts (shipped UPS, USPS and FedEx) to get to my house another few hours to disassemble and reassemble and now I have a running truck. I run through the Idle relearn from the Service manual and it takes perfectly, idle right back where it should be. For now it seems like my ECM is safe!

 

I couldn't have done it without the help and posts of NPORA and NicoForums thanks guys! You saved me a ton of headache.

 

Old Gaskets, get both they are cheap and after 160K mine where smashed flat and likely to not seal well again.

 

Old IACV, taken apart. Odd little thing, I can see the benefits of fly-by-wire on the '03 on R50s.

[rick88ss]

So it was the IACV? Did you have to remove the upper intake plenum to get to it?

Did you test the old one with a multimeter ?

[RedRider3141]

I removed everything between the MAF and Intake Plenum.So Rubber Intake boot/Resonator and Throttle Body with IACV attached.I ohm'd out the IACV per the manual and tested the plug at the truck end and all but one terminal on the IACV checked out. As I understand it the IACV is a multistage solenoid so anyone could fail and cause issues. The other issue i noticed was a ton of carbon buildup which couldn't have been helping. I cleaned the Throttlebody thoroughly while it was off the rig. I am glad I didn't attempt it while it was on the car.