I have a shorted out IACV on my 01 maxima. I've read through the horror threads cautioning about burning up ECU, burning up new IACV, shorted motor mounts etc. I wanted to ask for any wisdom about what next? I have/had no CEL before this (the 'ol gal won't idle, just dies). I'm not sure if I should go ahead and just replace IACV (I didn't have any codes being thrown?) or if I should look for a short in the motor mounts? What would be the resistance if I should? Thanks all!

 

Just wanted to let people know in case they go through something similar that I replaced the IACV and the car started and idled. I turned it off and am about to try the idle air volume re learn...we'll see

 

You could have tried cleaning the IACV first and the throttle body. It probably would have done wonders and cost you far less than replacing the IACV.

BTW..it really isn't the IACV that fails, but the gasket which you can replace by itself and not the entire IACV.

 

I went through this nightmare. And I didn't do it the proper way. In the end, I sent the ECU out to have AV Pro repair it ($140?), replaced the IACV twice, and disconnected my electronic motor mounts. Initially I only replaced the actual motor of the IACV, not also the aluminum housing attached to the underside of the throttle body - big mistake. The spring inside was bad. Sounds to me like you either got incredibly lucky, or you will be revisiting the problem shortly.

 

NO!
It is the iacv that fails quite often, If you read old threads most iacv fails when the coolant passages behind make contact and short out along with motor mounts.

Don't just plug a brand new unit hoping Its all Gucci.
Actually disconnect the harness and measure reference voltage and ground.
Max 5v with igniton-on

Batt-
To Harness pcm signal

 

as someone else said, if replacing just the IACV fixes the problem you are very lucky because most times the ECU is damaged not long after the IACV fails. if it were me i'd at least pull out the ECU and look at the STA509A MOSFET for any signs of damage, if nothing found, go on your merry way.

 

How does a coolant pass by? Failure of the gasket....so, ultimately the root cause is the IACV gasket and NOT the IACV itself. Why throw $100+ at a problem when routine maintenance of changing out the gasket can prevent it?

 

the gasket that fits between the IACV and throttle body on my failed IACV was in excellent condition and there was no sign of coolant breaching the gasket, so i don't think changing that gasket will help. i suppose there may be another gasket embedded within the IACV that is supposed to keep the coils from becoming wet, but that gasket isn't serviceable far as i know.

 

I was in the same boat as most with a blown ecu to go along with the bad IACV. One of the IACV coils measures 1 ohm and the MOSFET in the ecu was charred along with 2 traces. I replaced the entire valve with one of the eBay $49 ones after some folks said they had 2years on the eBay units without any issues.

One question. Is the motor mount motor issue directly related to the IACV or is it just the same type of issue (ie a motor mount motor failure can smoke the motor mount drive circuit within the ecu?)

Also, what is the purpose of the coolant going through the IACV housing? Emissions?

I didn't do the bypass. I am planning to pull the motor mount connectors

 

The motor mount is NOT the same problem - it just belongs to the same class of problems.

Re. coolant and IACV, ... "the coolant flows through the IACV valve; it heats the cold idle wax pellet type thermo valve during start-up. This valve allows more air to bypass the TB at first start up then as the coolant warms up the wax expands and closes the valve".

I suspect that the main reason is emission, and California emissions in particular.

BTW, I am at the same point with my deliberations: I disconnected the electronic engine mounts on my 2000 SE, and I am pondering what to do about the IACV. I am considering three options:
1. Coolant bypass (partial solution, since the IACV motor can still fail and fry the ECU, at least in theory),
2. Fusing the IACV (best solution, I wish i could find a kit somewhere),
3. Pro-actively replacing the IACV (this is only as good as the quality of the new part).

 

i'm also experiencing problems with my IACV, i think atleast.. my car idles sporadically whenever i'm stopped in drive at a light, it pudders and sounds like the cars gonna die but as soon as i press the gas it goes away, it doesnt do this all the time, maybe 1/3. the car drives fine and i dont have any lights.. could it be the iacv? i thought it was the maf sensor but my car revs above 3500. i'm gonna try cleaning it like you guys suggested and hopefully that remedies the issues.