Idle Air Control Valve (IACV) Replacement DIY for 2001 Pathfinder

[sroberts]

Can anyone point me to a DIY or a decent writeup on how to remove the idle air control valve on a 2001 Pathfinder? My searches only turned up a bunch of chatter.

Thanks!

[Buzzman]

One way to do it is to pull the throttle body off as a unit. Then you can remove the AICV and at the same time, clean everything up.
The IACV is held in with two screws, so it can be removed in the truck.
I pulled everything out and cleaned and replace the IACV and the valve body.

[atraudes]

Also plan on the screws not coming out nicely. I had to use an impact driver set to remove them and replaced the screws with some hex head bolts. Full thoughts here.

[sroberts]

I installed a Hitachi ABV0043 IACV a few months ago, I believe it is now bad. According to the "EC" manual, EC-424, the resistance between pins 2 and 1,3, and 5 and 4,6 should be 20-24 ohms @ 68deg F. I measured 9.3, 18.4, 23.0, 22.8. The 9.3 is less than 50% of spec. I suppose the resistance will get lower and lower until the engine control module fries. I just ordered an OEM IACV.

[atraudes]

I'm curious, what prompted you to check? Did you notice any symptoms?

[sroberts]

Symptoms started with occasional stalls at idle, becoming more and more frequent. I tried the air volume re-training but no help, and cleaned the MAF though it was not dirty, which also did not help. Then the SES/CEL light came on and the truck would not idle at all. I carefully drove it to the auto store and had P0505 read, which I kind of expected. So I removed and cleaned the air intake and throttle body, checked vacuum and all connections, tested the throttle position switch, inspected the IACV, and did a basic test to be sure its motor operated when the ignition went on and off. And the truck still did not idle. So I removed the IACV motor and found its resistance was out of spec. I ordered the OEM part, but I'm not convinced it being out of spec is the culprit. After I receive it and install it I'll post an update.

[atraudes]

Hm, good to know. I installed mine about a year ago and haven't had any problems, but recently I've been trying to track down an intermittent issue where my idle will drop a bit and become rough after coming to a stop. Sounds like it'd be worthwhile to test mine too...

Could you compare the OEM unit you bought to the Hitachi? I'm curious if the part numbers, markings, etc. all match up.

[yngw13]

Hi guys,

Did ALL of you replace the TPS after ECM repair?

I ordered a TPS just to eliminate future problems.
Mine just died but never had idle issues....

[atraudes]

I replaced my TPS because I had an oscillating idle caused by it going bad, but I remember seeing that it was a good idea to replace the IACV and TPS at the same time (I think because they have a similar lifespan). When you say "mine just died", are you referring to the TPS? What were you seeing that prompted the replacement?

[yngw13]

I meant that the truck just stopped idling...-died and didnt start anymore
It didnt suffer any bad starting or idle problems prior IACV/ECM failure...which I think the TPS is responsible for.

[atraudes]

Gotcha, thanks

[sroberts]

I have not replaced the throttle position switch / sensor. Mine is seemingly okay from a basic ohmmeter test along with the feeler gauge test per the EC manual.

atraudes, my failed IACV is a Hitachi ABV0043, I bought it from PartsGeek in June 2015 and it probably has less than 3000 miles on it. I ordered an OEM IACV, p/n 23781-4W002. I should have it by the weekend.

[Buzzman]

Hi guys,

Did ALL of you replace the TPS after ECM repair?

I ordered a TPS just to eliminate future problems.
Mine just died but never had idle issues....

Did not replace the TPS on mine, only the IACV.
BTW, a bad TPS will not take out the ECM, but a bad IACV will.

[yngw13]

^^^

Ok in that case Im taking my ECM/IACV to the shop tomorrow.
I was going to wait for the TPS in the mail...

BTW...does replacing the TPS require an Idle Relearn?


Thanks Buzz

[sroberts]

I received the "OEM" IACV today, installed it, and my Pathfinder now idles just perfect. Before installing I confirmed the resistance between the control pins was in spec.

My new Nissan OEM and failed Hitachi ABV0043 IACVs appear to be exactly the same, and are likely produced on the same equipment. Even the smallest markings and mold seam lines match. The only differences I found are:
- One ID stamped is different, my guess is it indicates a different production run ID
- the Hitachi has a ABV0043 sticker, the OEM does not
- The OEM comes in a NISSAN Genuine Parts box, the Hitachi comes in a Hitachi box
- The OEM is $150-$300 depending on your source, the Hitachi is around $90

I suggest anyone having idle problems, and especially a P0505 code should follow the P0505 diagnosis guidelines in the "EC" manual (http://www.nicoclub.com/archives/nissan ... nuals.html) including testing the resistance on your IACV with an ohmmeter. If the resistance is below spec you should consider parking your Pathfinder pending IACV replacement or run the risk of damaging the ECM.

New OEM labeled IACV on top, failed Hitachi labeled OEM on bottom:

[atraudes]

Thanks for posting those photos! Hitachi certainly does seem to be the OEM, which is good and bad news. Good because it means OEM can be had for around $90. Bad because we don't have much certainty that the more expensive part is going to last any longer... I'm willing to bet every other brand you can find out there is probably made by Hitachi too. That's what I found with SMP when I was looking at fuel components. Well, here's hoping you don't have to think about this thing again one way or the other!

[TheReplay]

I just replaced mine with a Hitachi unit (FYI i ordered mine from amazon and my mechanic told me it did NOT come with the gasket). The IAC fried one of the ICs in the ECM. So I ordered a couple replacements off ebay and soldered a new one (total cost was 15$ for two ICs). I looked over the printed board very well for burned up traces and other damage but did not see anything. I didnt want to send it out for repair because I have a schedule that wasnt going to work with the downtime.

Anyways, my mechanic replaced the IAC valave, but stopped short because he couldnt get the relearn to work, so I brought it home and repaired the ECM. so far so good, it was idling @ 900-1000 when I installed the repaired ECM. after relearn its at about 800-850 in park/neutral, and then drops to the 700 mark when in gear.

Fingers crossed that I didnt need to replace the TPS (I bought one, but Im not sure I knew how to replace it and set it, I wanted to go one step at a time, and so far this is working).

My truck has been sitting for a long long time, so I am happy to get it back on the road.

[yngw13]

I just replaced mine with a Hitachi unit (FYI i ordered mine from amazon and my mechanic told me it did NOT come with the gasket). The IAC fried one of the ICs in the ECM. So I ordered a couple replacements off ebay and soldered a new one (total cost was 15$ for two ICs). I looked over the printed board very well for burned up traces and other damage but did not see anything. I didnt want to send it out for repair because I have a schedule that wasnt going to work with the downtime.

Anyways, my mechanic replaced the IAC valave, but stopped short because he couldnt get the relearn to work, so I brought it home and repaired the ECM. so far so good, it was idling @ 900-1000 when I installed the repaired ECM. after relearn its at about 800-850 in park/neutral, and then drops to the 700 mark when in gear.

Fingers crossed that I didnt need to replace the TPS (I bought one, but Im not sure I knew how to replace it and set it, I wanted to go one step at a time, and so far this is working).

My truck has been sitting for a long long time, so I am happy to get it back on the road.

Thanks for sharing!
do you have pics of the board and/or fried chip?
And what is the model.name # of the chip?
Its nice to know that this is doable...

[TheReplay]

Whats that they say about coutning chickens before they hatch...?

So today I replaced the belts and the bank1 sensor2 o2 sensor.

cleared my codes and went for a drive trying to cycle the OBD2 system so I can bring my truck for emissions... I pull into my driveway after about an hour or so running errands and...

No engine light, but I plug my code reader in and find p1448, P0455, P0505 (IAC) ---

The car is running just fine, not like it was before... I just dont get it... it never ends... I was relaly hoping to get this truck back on the road, but the more and more I try the more discouraged I get. I set my limit @ 1000 bucks to get this thing on the road... so far with a new IAC/new coil pack/new belts/new o2 sensor/labor/ I am @ about $450... I need to factor in registrations, and a set of tires -- I just think it may be time to cut my losses.

Anyways the chip was part number STA509A and located @ IC17 on the board... I dont have a pic of the board but here is a pic of the chip and as you can see it burnt up and actually cracked..

[yngw13]

...how did you do the idle relearn?

I would think you have to bring to the dealership to have mechanic do it.

[TheReplay]

...how did you do the idle relearn?

I would think you have to bring to the dealership to have mechanic do it.

There is a procedure that is done without the tool that the dealer uses.

[wmj259]

Please post the procedure that you used as I am having so much trouble with this truck.........

[04pathse]

Please post the procedure that you used.

The idle relearn procedure can be found here on page 71

http://www.nicoclub.com/FSM/Pathfinder/ ... der/ec.pdf

[wmj259]

For the PRECONDITIONS, can you elaborate or better explain what they mean?

Battery voltage: More than 12.9V (At idle)
- Engine coolant temperature: 70 - 99°C (158 - 210°F)
- PNP switch: ON <<<<<<<<<what does that mean?
- Electric load switch: OFF <<<<<<<<<what does that mean?
(Air conditioner, headlamp, rear window defogger)

[wmj259]

I tried doing the turn key on off crap so many times especially with the hold gas pedal for 20 seconds.

[wmj259]

.
Just saw this video to lower my idle rpm. The video is on a frontier/xterra.
Will this be possible for the pathfinder? Also how do I confirm BTDC?

[sroberts]

For the PRECONDITIONS, can you elaborate or better explain what they mean?

Battery voltage: More than 12.9V (At idle)
- Engine coolant temperature: 70 - 99°C (158 - 210°F)
- PNP switch: ON <<<<<<<<<what does that mean?
- Electric load switch: OFF <<<<<<<<<what does that mean?
(Air conditioner, headlamp, rear window defogger)

I think it pretty much means to warm up the truck and make sure your accessories are off, including A/C, headlights, etc. If you performed the training and your truck still does not idle properly, you'll want to check the TPS for proper adjustment (described in the EC manual). If you've not already, check the MAF and IACV as well.

[wmj259]

I lowered my rpm by turning the tps. MY Snap-on scanner is telling me there is a screw on the IACV valve. I do not see a screw on it. Someone help me with this.

I've done the relearns probably 20 times now. But the only one I cant get done is the IACV one. When it says in the step to hold the gas pedal for 20 seconds till the SES light comes and stays on?
But the thing is I dont have any lights on at the moment. cluster is clear of lights.
It comes on and it just doesnt stop flashing. It probably stays on for 2 seconds and flashes and 2 seconds over and over again. Is that what it means?

[wmj259]

I guess the issue is with the TPS or IACV that I just got. Not getting any SES light or any codes. :/ :/ If I follow this

Throttle Position Sensor NAEC0419 Throttle valve conditions Voltage (at normal operating temperature, engine off, ignition switch ON, throttle opener disengaged)
Completely closed (a) 0.15 - 0.85V
Partially open Between (a) and (B)
Completely open (B) 3.5 - 4.7V

I measure this by putting a wire into the TPS brow connector middle port.






I moved the tps back to about its original position, and my idle rpm is about 1800 now at normal engine temperature.

[sroberts]

I've done the relearns probably 20 times now. But the only one I cant get done is the IACV one. When it says in the step to hold the gas pedal for 20 seconds till the SES light comes and stays on?
But the thing is I dont have any lights on at the moment. cluster is clear of lights.
It comes on and it just doesnt stop flashing. It probably stays on for 2 seconds and flashes and 2 seconds over and over again. Is that what it means?

When I did the programming on my 2001 I also never had the SES light stay on and was not sure if my training took hold or not. But it idled just fine after replacing the IACV. Also I was under the impression that the ECM would eventually train itself, but I could be wrong about that.