ManualMaxima

iTrader: (10)

Thank you! I've come to the same conclusion concerning an OEM IACV, and we ordered one 2 nights ago. We'll see how that goes. Thx again pilm...

TunerMaxima3000

iTrader: (4)

I'm not buying an OEM IACV until it's the last freaking option I have. This one isn't shorted, and I can physically watch it move in and out during it's cycles, so that's good enough for me.

The idle setting point is a huge part, I don't think I can accurately do anything until I ensure the Idle is 'learnt' 100%, because the ECU clearly looks for a specific parameter in RPM and if that's wrong, bam, P0505.

I think I might have a vac leak recently started also because my Long term fuel trims are at 10%, So I need to address that and get my idle set.

I'm going to be checking/replacing the Mosfet in the ECM whenever the replacement arrives and I get time, but until I get the idle properly set and any vac leaks fixed, it's all pointless.

olypopper

I went to Napa and Orielly and tested both IACV's they had in stock and neither one passed a resistance check. I ordered one from Nissan as I feel that it will be much better quality than the aftermarket options. Also, the original on my car lasted 160k miles so even though it seems initially to be a poor design, it lasted an awefully long time.

FYI-I just got my IACV from Nissan and tested it, 21.8-22.0 ohms per circuit. The aftermarkets were 9.0-25.0 ohms per.

TunerMaxima3000

iTrader: (4)

That's very interesting info!

olypopper

I got mine back together tonight and it runs great. I opted to have my ECU repaired by Digital Auto Technology in Corona, California for 200.00 vs. 700.00 for a factory reman that would need to be programmed by the dealer. My ECU only had a burned STA509 chip and suffered no board damage to speak of. I really lucked out in that respect because when I installed the new OEM IACV and the repaired original ECU the car started right up with no codes and didn't even require a re-learn of the idle function. I did spend a little extra time cleaning grounds and intake plenum, etc as well as making certain the throttle on/off portion of the TPS was functioning correctly and making sure the TPS had a smooth transition from idle to WOT position. This ultimately cost me about $500.00 including shipping so I can't complain. The dealer quoted $2400.00 for this repair and acted like they had never heard of a failed IACV! I'm glad I found this site.

ManualMaxima

iTrader: (10)

^
Happy to hear at least one person has a good ending to a p0505 story. Glad it worked out for you...

Pilm

My experience was identical, idle was spot on after installing a new OEM IACV and a self repaired ECU, no codes and didn't need to do an idle relearn. I also recalibrated my TPS since I removed it to make sure it was working properly. It's been a year now and hasn't come back so hopefully you'll have the same fortune.

TunerMaxima3000

iTrader: (4)

Awesome, but counting your chickens before they hatch maybe I hope it doesn't return

olypopper

ManualMax, what's up with your car? I want to see you win this fight! I drove my car all day today and had no issues with the exception of scaring the hell out of myself by trying to start the car with an unprogrammed key!!! I finally realized what happened and then got my head out of my a** and started it with the correct key. PM me if you have questions. I'm no pro but I spent a hell of a lot of time diagnosing this problem and have quite a bit of this maxima figured out.

olypopper

A quick update on my fix. It's been running good but tday when I started it up (outside temps hovering around -7 F) it started ok but immediately started a slight surge. No codes, just a small surge. I let the car warm up fully and drove to work (probably a 15 minute warm up) and let it sit outside, not plugged in until lunch time. I started it up cold to warm up and it started surging again. Let it warm up fully and drove to lunch, no issues. Tonight after work I plumbed the IACV coolant hoses back to the IACV and topped off the coolant. Cold start was much smoother with no surging. I'm going to start it up again in the am, cold to see if it's that touchy on the cold start. Looks like some cars may be a bit finicky when it comes to the IACV coolant bypass trick. It would probably be fine if I weren't in the frozen Arctic!
(FYI-Car has been in a garage until last night and today when it was outside, I think that's why I had no problems with surging till today)

TunerMaxima3000

iTrader: (4)

What are the temps there? I've never had a cold start issue on my car with the TB bypassed all the way down to -25* C

olypopper

It's been down to -10 F. I had it in the garage all night and it fired up straight away and ran great. This afternoon after sitting outside all day it fired up and ran well also. My car seems to be picky.

TunerMaxima3000

iTrader: (4)

strange dude

ManualMaxima

iTrader: (10)

Well I never want post with a problem and not report the outcome, so here it is after getting it fixed today! After we were at our wits end with this problem, and the car sat for awhile, we finally broke down and took it to the dealer for diagnosis. First let me tell you the "Consult II" diagnostic computer the dealer uses is amazing! It took all but a few minutes to find the solution to same problem that we had spent A LOT OF TIME ON. The tech who worked on it took us back to the garage and showed us the readings as he was working on it and actually controlling the IACV from the Consult. Well here my problem/solution is; the ECM

Note: I had the original ECM fixed / it fried again along with taking out the replacement IACV / we then sent it back to get it fixed again, and are told by the repair company tech that it wasn't their fault the ECM failed (it was mine apparently); and not covered under their limited warranty / they fix it again and we get it back for round #2 after paying for service again. Once back and after we install it (also #2 new IACV), I couldn't get it to accept relearn at all. At this point, as I've posted before we went rounds and rounds with this car checking and double-checking everything. Well the dealership with their Consult II went right in and determined it was the ECU, which just happened to be the one part I couldn't and hadn't had the tools to test, and believed to be the one part I could count on as not being the problem. I've been all over this damn engine and the whole time it was a bad ECU that the repair company said was good not once but twice!!! Don't even tell me to go demand my money back from these people because tomorrow morning we are getting some apologies and a damn refund ASAP if not more (they advertise on the net specifically for fixing this nissan ECM issue). I got the dealership to put in writing the cause and specifically that the ECM wasn't controlling the IACV valve even close to proper specs!!! This company wasted my time, my money, and has given me a headaches to no end. I'll post my results with them as well after I talk to them tomorrow and if I'm not satisfied with what they will do for me I'm going make it my personal mission to tell everyone my negative experiences with this company especially on any forum their name comes up (but I will give them the CHANCE to try to make things right before I do so).

On one hand I'm mad of course, but also I am glad to see the Max purring perfectly at idle now as we dropped in a new ECM and just had the dealer re-key and do the idle re-learn. And hopefully I learned my lesson on rebuilt ECU's, as from now on I'll always just spend the extra dollars and go right to a new ECM. Glad to see her running again...

defiance

iTrader: (1)

Oh wow im glad it finally got fixed ! To bad you had to take it to the dealer though,but atleast its fixed ! I don't even want to ask how much you had to pay the dealer for the diagnosis and new computer !

TunerMaxima3000

iTrader: (4)

Thanks for posting the resolution! That's very good to know, sounds like these guys just replace the one chip and that's it. This is vital info for the rest of us!

Pilm

Glad you got the car working again. I hope you get a positive resolution with the ECM company b/c they obviously failed to repair it properly. I never liked it that they put that bogus warranty void seal on the repaired ECM which discouraged you from opening it up and checking what they did. And then they charged for the 2nd repair anyway, so bogus! If you don't get positive resolution be sure to publish their name here and I'll help spread the word about them as well.

2001M20

So happy to find this thread while looking for answers on this issue. I was so disgusted to smell that burning smell so soon after getting my system repaired and I am not looking forward to going through this again. I will pass this info along to my repair man and hopefully he can avoid some of these headaches. I will also post any helpful learning I gain from this hurdle and hope it's a long term fix you found. I think they failed to undo my elec. motor mounts like I asked in the beginning and I will research this fluid issue as well as looking into the bypass of coolant etc. Thanks!

2kMaxim

Im glad the partys involved in this thread got it resolved! I have never had this issue, nor any warnings of anything going downhill as far as the IACV. Do I need to worry about this and replace something before I get this code? Or does this only happen on some max's....

olypopper

ManualMax, did you get the resolution you were hoping for?

Darkrock

Read most of the postings but this I know...the IACV is a piece of junk! I posted the following a while back but seems to be another cycle of problems.
--->IACV Oversensitive or Underlying Design Fault
On 1/09/2012 daughter breaks down in Maxima and I go to fetch her and "it" hopefully. Cold starts fine and idles at 7-750 and I am thinking a bad batch of fuel. Until "it" warms up and the throttle commences to surge on warmup while running up the Stevenson at 12am and it doesn't like 2000rpm at all. Drives better over 2k than under 2k and at idle "it" is high at 1500rpm. These symptoms remain...Cold start and idle are in spec ...until "it" warms up...Surging (2-3K) at idle and running and when not surging a high idle of 1500. There are 2 codes for the dreaded P0505 and thi8s cannot be...
1. This is a 2001 A/T GLE and "it" eats IACV! In Fall of last year "it" ate another IACV and an ECM and I documented the repair under the thread ECU Fried In Seconds post and finalized with a Coolant Bypass of the IACV. It cannot be the IACV at fault it is now bullet proof...with the repairs I made.
2. I run through the litany of EC faults in my head and decide to do an Idle Relearn. I do it several times NG.
3. Break out TunerMax's checklist and start going through it and I am testing the IACV and each of the 6 pins are between 21-24ohms. Note I did not check CONTINUITY!
4. Decide to retune the TSP by using the .05 & .15mm gap at cable and multimeter at lower set of pins. Finally get it done. TSP relearn done. Same symptoms remain and I pull the IACV out again and check the pins which all test within spec. But this time I check CONTINUITY AND PIN NUMBER 4 MAKES A SLIGHTLY DIFFERENT SOUND! Note the ohms are all in spec at 21-24ohms.
5. Return it to AZone check the new one in the store for resistance and continuity and reinstall it with TSP retune and it purrs very nicely. Maybe 6 hours of actual frustration to correct it back to normal. What is there in this design that has such little tolerance for error? Sorry just a little rant!

ManualMaxima

iTrader: (10)

No I didn't! Cannot recommend Circuit Medics at all! Kept telling me that they had never had a failure with any ECM they have repaired "EVER". After many emails I finally had to send them the ECM back and send paperwork from the stealership for them to agree they messed up. So got my money back on that one, but they then wouldn't budge on the first repair that also failed. I couldn't prove they messed it up (tamper resistant tape all over the repaired ECM), and they sure weren't going to tell me they messed up, so I got ripped! It was my opinion that after all their "we've never messed up talk" and finding out they did mess up, that really cast doubt on the first repair. I hate em!!! Shady shady shady, would never recommend them and still get upset thinking about how much time I wasted even dealing with them. Beware...

-This is the very shortened story :-(