Kaleobz

2001 Maxima SE 5-speed. 165k. Last week my wife gets home from work and lets me know our Maxima is acting funny. Idle was low and rough and feathering the throttle would stall it out sometimes. I have had a SES light on for some time now for pre cat function (p0430) but haven't addressed the issue because it hasn't affected drivability. Drove the car to autozone to have it scanned for additional codes since the SES is already on. Got a P0505 that concerned me because the car wouldn't run all of the sudden at autozone. I had to give it gas to start it and keep it running otherwise it would stall out and i drove it home like this about a mile. After researching this code I became really concerned after hearing of others ordeals replacing IACV's ECM's TPS's etc. sometimes multiple times. My IACV failed the tests from the FSM and there were signs of coolant leakage on the lower IACV coolant hose. I pulled my ECM and opened it up to check for obvious damage. Nothing. It looked and smelt fine. So I crossed my fingers and ordered an IACV off ebay for <$70. Removed the throttle body to remove the old IACV and the seal was definitely leaking. Cleaned up the throttle body and installed the new IACV that came with a factory seal and put it all back on the engine. The Maxima started right up. After warm up the idle was good and I could tell it was trying to figure itself out after having the ECM disconnected. It drove well and I could not get it to stall anymore. No SES light. I checked drivability again later and all was good. At that time I went ahead and performed the idle relearn without consult and I think I nailed it on the first try as the idle is holding steady now and not trying to figure itself out. Im hoping this is where this will end and that I was fortunate to catch the problem early before ECM damage.

moogotzskillz2

I had a similar issue couple weeks ago, cleaned my IACV helped the idle for a couple of days then stalling happened. i replaced the MAF and air temp sensor(i think its called) located on the ram air intake behind radiator. that fixed the stalling...

Btw i hope u clean ur throttle body just keep it maintained..

a33nismo

Looks like you might have caught it in time since once coolant starts to leak into the iacv motor it almost always fries the ecm.

But if it did fry you should see it easy looks like a mini fire on the chip.

Kaleobz

Yes, I saw many pictures of burnt ECM's like that one. I think I am fortunate that I caught the P0505 in time and my ECM wasn't compromised. Today is the first normal driving day and after 20 miles the Maxima is driving great thanks to the clean throttle body, MAF, air intake, and the idle looks solid at around 650rpm thanks to the new IACV and idle re-learn.

My advise: If you have rough or erratic idle and or stalling symptoms suddenly and a P0505 code pops up, stop driving ASAP. Test your IACV and if its bad, check your ECM for obvious damage.

My IACV was bad but my ECM looked good and replacing the IACV fixed my problem. This is not the norm from the research I did. More often then not others had to replace their ECM's as well.

noahrexion

Mind sharing where you ordered your iacv from? Seems most have problems w/ aftermarket; apparently you did not.

nsnrider

iTrader: (59)

change out the iacv with oem parts.

ps...i've seen a bad ecu without any visual signs like the photo posted above. don't drive the car untill you replace the iacv. don't waste money on a used one either.

Kaleobz

Got my IACV from eBay seller: autotecpartsusa
They have good feedback ratings and the part was cheap. It came with a factory nissan seal but no screws. I figured if my ECM turned out to be bad and shorted the new IACV then why would I buy an expensive one? My worst case scenario appeared to be another IACV and an ECM repair. I am fortunate that it did not come to that. Hopefully my new IACV will last.
Now I guess it is time to tackle my P0430 code which keeps popping up. eBay had a pre-cat for $125!

Flizr6

Since I don't have this issue yet (119,000 miles), is there any preventative measures that could/should be taken?

Child_uv_KoRn

iTrader: (7)

*sighs* (at least it's in a relevant thread haha)

Bypass the water connection to the IACV. Get a new piece of longer hose and just completely bypass it.

This is basically mandatory when you buy a maxima with an IACV. Also, unplug the motor mount(s).

Darkrock

Kaleobz,
Child uv Korn suggestion is a good one--> "Coolant Bypass" get a simple hose mender kit (I used a brass fitting) from the hardware store and cap off those 2 pipe ends. Not sure if MT has electronic motor mounts but the Final check needs to be at the TSP loosen those screws and dial it in__go easy on the tightening of the screws__the plastic is brittle. Good Luck!

Child_uv_KoRn

iTrader: (7)

Yeah, oops, I think only auto has electronic mounts.

Kaleobz

I will have to try the coolant bypass for the sake of the new IACV. Why does the IACV have coolant pass through in the first place? Cant be that important if many are just bypassing it.

Darkrock

I re-posted this on a different thread but it seems relevant here as well. There is a quality problem with the manufacturing of the IACV and I dont think it matters who made it. You must check RESISTANCE AND CONTINUITY before installing a new IACV.====>>>


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!