Anyone successfully fixed their idle problems?

[zach7685]

My problems began a year ago on the coldest day in December. In my situation, I was leaving work and the car pulled like it was under load all the way home. Got home restarted the car and there were no issues. The next week (on the coldest day) it was about 27 degrees out and the car would not start. I had it towed to my mechanic, who told me that it had spark but no fuel. After a couple days, he found a burnt out fuse. He replaced it, but it kept blowing. Eventually he found that the idle air control valve was stuck. He replaced it with an aftermarket unit, but informed me that it would stall out until it ran for a few minutes.

I get the car home and the idle begins fluctuating from 500 RPM- 3,000 RPM. My mechanic sends me to a Nissan specialist, and they inform me that the aftermarket idle air control valve was the cause of the idle problems. They replaced the IACV with an new OEM unit and re-program the system. I get the car back and it ran like it was supposed to. After about a week of having the car back, the idle was off, fluctuating, and I need to give it gas to stay running. They told me that I needed to replace the IACV with a new ECU as they think that the one I have is shot.

Fast forward a year later, it still requires gas to get it started up in the morning regardless of temperature, but idles fine after about 8 seconds of me keeping it at idle. When I let off the gas it idles low but it does not stall. For reference, it idles low enough that the A/C clutch disengages. This year again on the coldest day so far, the idle fluctuations began again.

On the first cold day the car does this when I first started it: https://www.youtube.com/watch?v=1SIdvj4RmdE. After i restarted it it worked fine.
It appears that there is a correlation between cold temperatures and idle problems, at least in my experience.

Anyone else with similar issues or has successfully fixed the issue with a computer replacement? Sorry for writing an essay but I had a lot to see if others have the same problem.

[Buzzman]

Last year at this time (winter of course. Never happens in the summer): Intermittent, then no idle.
Replaced IACV with new Nissan part (no fooling around with used or third party parts for this problem),
repaired ECM, did idle relearn....running like new for the last year.

[zach7685]

Did you fix or replace the ECM?

[Buzzman]

Did you fix or replace the ECM?

Fixed. Sent it out to Circuit Board Medics (In one of the Carolina states, not sure if it was North or South).
$250.00 flat rate repair.
New OEM IACV.

Are you getting any fault codes?

A P0500 or P0505 is a pretty solid indicator that your ECM is blown.

[zach7685]

I do have a P0505 code some times it says pending some times it does not.

[Buzzman]

I do have a P0505 code some times it says pending some times it does not.

In most cases, the ECM will not go bad the instant the IACV starts to act up.
What happens is that people continue to drive with a flaky or bad IACV.
Eventually the ECM says enough is enough, and the circuit controlling the IACV goes bad.
When that happens the truck will not idle at all.
If I were you, I would replace the IACV before blowing the ECM.
Even unplugging it may save the ECM.
You can always tweak the throttle cable to help it idle without the IACV working.

[zach7685]

I've replaced the IACV 2 times so I guess it is the computer. Im guessing if I fix the ECM I'll need to buy a third IACV so as not to fry the new ECM.

[Buzzman]

I'm guessing if I fix the ECM I'll need to buy a third IACV so as not to fry the new ECM.

Not necessarily.
In a funny kind of way, this situation is a one way street.
A bad IACV will take out an ECM, but a bad ECM will not take out the IACV.
That's why you should never fix the ECM without replacing the IACV.
Doing it the other way around is OK though.

Depending on where you got your IACV's (new, used, OEM, third party??), I suspect they are OK.
Now it's just a matter of getting the ECM checked out.

[zach7685]

That makes sense.
I guess I will tell them that I replaced the valve a year ago and see if I still have to buy a new one for the warranty on a rebuilt ECM.

[atraudes]

Where are you getting the OEM IACVs? RockAuto and Amazon both only show Wells and SMP, and infinitipartsusa.com doesn't have the part at all. Auto Zone and Advance Auto's website both indicate that the Hitachi ABV0043 fits (and is the OEM part, I'm presuming, since the rest of the throttle body is Hitachi), but other sites show that it doesn't fit. It's also ridiculously cheap compared to the others ($100 vs 200 and up).

I'm so cornfused

[Buzzman]

For me last year, I bought the IACV and the housing at a Nissan dealership in Florida.
It wasn't cheap, but it was still priced lower than what I would have paid back home in Canada.

[Km1ll3r91]

I literally have the exact same start up senario as you and have also done iacv ecm repair handling it myself, u should look into idle air return, supposedly you can do it yourself but I notice no difference however having the dealership do it did fix the problem however my car must have forgot or reprogrammed on it own and is back to the same non sense so I just deal with it rather than pay I for a idle air volume relearn there are also Bluetooth android obd2 apps that provide work support for the idle relearn however I never noticed any difference I was following all FSM directions while perform both methods myself

The idle air relearn can be found in the EC section of the Full service manual worth a try since it is fairly simple just unpluggi the iacv in the correct sequence

[Buzzman]

After I replaced the IACV and the rebuilt ECM, my idle was steady, but over 1000rpm's.
I got an idle too high fault code as a result.
I must have tried the idle air relearn process as per the FSM a dozen times. Never worked or took hold.
I took it to my dealership where the tech I always deal with did it in less than 5 minutes with his scan tool (no charge).
It has idled and run perfect for the last year.
Was I doing something wrong? Could be, but I never figured it out.

[Km1ll3r91]

so @buzzman your saying that the idle relearn did ultimately fix the problem for you?

im thinking about redoing all parts, iacv and crank cam sensors with nissan oem parts. i know i used all oem spec parts but not from nissan. followed up by the idle relearn.

[Buzzman]

so @buzzman your saying that the idle relearn did ultimately fix the problem for you?

The new IACV and rebuilt ECM fixed the no idle problem.
The relearn fixed the high idle problem.

As I said in the previous post, after replacing the parts, the idle was rock steady at just over 1000 RPM.
The relearn brought it back down to the normal 750.
It has been dead on steady ever since.

[Geo46]

My 01 pathfinder died. Towed it to the dealership got a diagnosis that the ECM and IACV is bad. Towed car to home. Purchase new IACV and had ECM repaired at Digital Auto in California. Today we replaced the IACV and reattached the repaired ECM, changed the engine oil and oil filter but the car still will not idle. Any ideas or suggestions?

[atraudes]

Reference the EC section of the FSM and perform the "idle air volume learning" procedure. If that doesn't work, start double-checking your work and make sure everything's connected properly and seating properly.

[Buzzman]

Today we replaced the IACV and reattached the repaired ECM, changed the engine oil and oil filter but the car still will not idle. Any ideas or suggestions?

Does the truck start and run if you keep your foot on the gas?
Are you getting any fault codes?

After replacing those two pieces, it should run and idle, although the idle may not be at 750RPM's.?

Also, when you replaced the IACV, did you remove the throttle body to do it?

[asnorton44]

My 01 pathfinder died. Towed it to the dealership got a diagnosis that the ECM and IACV is bad. Towed car to home. Purchase new IACV and had ECM repaired at Digital Auto in California. Today we replaced the IACV and reattached the repaired ECM, changed the engine oil and oil filter but the car still will not idle. Any ideas or suggestions?

MAF?

[jl2002]

Don't forget to change the 10a fuse under the hood. In the box on Pass side. Engine won't run until fuse is changed.

[QCtech]

Does this apply to the 2003 Pathfinder model? There is no IACV in the parts diagram for 2003,just the throttle chamber but yet I have exactly the same problem.

[Legend11]

BUMP - Any last minute advice on going OEM IACV vs HItachi IACV from RockAuto? The savings is tempting, but concerned about the quality of the Hitachi part. The gamble in frying my ECM is starting not to seem worth it, but I'm curious on other forum members results with the Hitachi IACV.

[Pathie]

Legend11
I only recently signed onto NICO but have been a long reader of.
Here is how my IACV/ECM failed.
I was aware of the coolant issue in the IACV and two years ago when changing plugs etc., I made it a point to check the throttle body for leaks. Every thing looked fine.
This winter when the temp was -20, and I park this vehicle for the winter, a lot of magnesium chloride is sprayed on the roads, when I notice a coolant leak from the throttle body. I removed, replaced gasket, and did notice a very small amount of coolant in IACV chamber, cleaned and re-installed.
I just started driving recently as spring is coming, took a 200 mile trip and upon start up, (200 miles away) the bugger would not idle, ran fine otherwise, had to feather the throttle all the way home.
Pulled IACV and number three coil failed, pulled ECM and it looked perfect, no signs of damage.
Purchased the less $100 Hitachi IACV (Amazon) and installed, note, the purchased IACV looked identical, same press marks etc. Started vehicle and still the same, no idle. I drove to our only Nissan dealer and told them exactly what I wanted to have checked, ECM for damage with their Consult tool, this was a waste of money $59 and they would need more time to diagnosis.
The part in the ECM as you probably know is a mosfet that controls the four coils in the IACV, which I had and ordered at the same time as the IACV. I tried to test this mosfet on the board which is tough to do and did get a little error on the same number three.
I checked out our only electronic repair business in the area 'UBreakIFix, was going to do my self but would have required my to purchase a lower temp iron, solder sucker etc., but this guy at the business above let me look at some of their tools and work he had done and I was pleased. Cost me $40 to solder in the part.
Runs perfect now, but did have to to the idle relearn procedure.
Here is the last caveat, this Nissan dealer is expecting me back for an air bag recall, and only the recall, of course they wanted my to buy factory IACV $300, and ECM $2200.
One last thing I disabled the coolant to throttle body with no ill effects.
Good luck
I have 135000 mile on this vehicle.

[Legend11]

Legend11
I only recently signed onto NICO but have been a long reader of.
Here is how my IACV/ECM failed.
I was aware of the coolant issue in the IACV and two years ago when changing plugs etc., I made it a point to check the throttle body for leaks. Every thing looked fine.
This winter when the temp was -20, and I park this vehicle for the winter, a lot of magnesium chloride is sprayed on the roads, when I notice a coolant leak from the throttle body. I removed, replaced gasket, and did notice a very small amount of coolant in IACV chamber, cleaned and re-installed.
I just started driving recently as spring is coming, took a 200 mile trip and upon start up, (200 miles away) the bugger would not idle, ran fine otherwise, had to feather the throttle all the way home.
Pulled IACV and number three coil failed, pulled ECM and it looked perfect, no signs of damage.
Purchased the less $100 Hitachi IACV (Amazon) and installed, note, the purchased IACV looked identical, same press marks etc. Started vehicle and still the same, no idle. I drove to our only Nissan dealer and told them exactly what I wanted to have checked, ECM for damage with their Consult tool, this was a waste of money $59 and they would need more time to diagnosis.
The part in the ECM as you probably know is a mosfet that controls the four coils in the IACV, which I had and ordered at the same time as the IACV. I tried to test this mosfet on the board which is tough to do and did get a little error on the same number three.
I checked out our only electronic repair business in the area 'UBreakIFix, was going to do my self but would have required my to purchase a lower temp iron, solder sucker etc., but this guy at the business above let me look at some of their tools and work he had done and I was pleased. Cost me $40 to solder in the part.
Runs perfect now, but did have to to the idle relearn procedure.
Here is the last caveat, this Nissan dealer is expecting me back for an air bag recall, and only the recall, of course they wanted my to buy factory IACV $300, and ECM $2200.
One last thing I disabled the coolant to throttle body with no ill effects.
Good luck
I have 135000 mile on this vehicle.

Thanks for the info. I actually went ahead an ordered an OEM IACV and IACV gasket from a Nissan dealer ($211). I'm also going to replace the Throttle Body gasket as well after I clean it. The only real symptom I have is the P0505 light and a slight rough idle. The truck's IACV did check out fine, so I'm hoping I'm catching it right in the beginning stages. If I still pull the P0505 code, I will check for vacuum leaks, but will start to investigate the ECM. I appreciate the tip on using a local repair shop as it is just a solder job.

[rgk]

For what it's worth, I ordered the Hitachi 'actual OE part' ABV0043 from Rockauto in 2016, and it has been working beautifully ever since. I had an eBay seller rebuild the ECM for $100. If you can return the dealer part and order the Rockauto, I'd go that way and save some money.

I would do some more research if I were you, because I think that if you have the P0505, it might be too late for the ECM.