02 Pathfinder Idle Issues

[harrimann]

Hello all,

I'm hoping to get some guidance on an some issues I'm having with my 2002 Pathfinder.

1st off we were driving home from a camping trip and the CEL started to flash and the engine was shaking pretty bad, when we got home I pulled the plug on cylinder # 3 (as this is where the misfire was according to the ODBII) and noticed that the spark plug was in very poor condition. I replaced all the plugs as well as the ignition coil on that cylinder and changed the oil (now this is a whole other issue as the fram computer told me to get this specific filer, which was much smaller than the one i had purchased before, odd i thought. So I called fram and they confirmed that the smaller filter was correct??).

About a week later the Pathfinder started to idle funny. At first the idle would slowly drop until the engine cut off completely. I took off the idle air control and cleaned it with seafoam, re-assembled everything and it seems as if the problem was solved. I might mention that when the idle was dropping the cel came on and the code said "High idle detected, faulty idle control valve". This is why I decided to clean the idel air control valve. However the issue is still there and just yesterday the cel started flashing, so I pulled over and pulled the code. Now it says cylinder 4 misfire, I cleared that code and luckily made it home. I also tried to do the idle relearn procedure, however the car won't idle the necessary 30 seconds, it just dies.

I must also point out that when the idle air control error showed up i also had 2 o2 errors, one for side 1 bank 2 and side 2 bank 2. However when I had the misfire those codes were not there. I should also mention that the resonators were recently replaced as I thought this could be the cause of idle and o2 errors.

So I have ordered a new idle air control valve. However something tells me that this might not be the issue with the vehicle.


Thanks in advance

Harrimann.

[Buzzman]

First, a major word of caution: If the IACV is bad, do not put the new one in without repairing the ECM.
A bad IACV will take out the ECM. Installing a new valve will just kill it again. They are not cheap.
This is a known problem. I've been there and it's not fun.

OK, now having said all that, what codes are you getting to tell you that the IACV is bad? If it's an 0505 code, your ECM is definitely bad.
Here is a two page thread on the subject. My experience is documented in the latter half of the thread.
Hope this helps.

2002-pathfinder-wont-idle-any-suggestions-t530479.html

[harrimann]

So I need to replace the ECM first? Otherwise the ECM is going to destroy the IACV? What part on the ECM fails? Bad caps/resistors? If I take it out and take it to my local electronic shop will they be able to fix it? This makes me sad. I had a 1996 Nissan Pickup that had 350,000 miles on it, and I never had any of these issues. I miss that old truck. This pathfinder has been nothing but issue, after issue. I hope its just the old age of the car showing and not a sign of spotty manufacturing.

[harrimann]

Just thought I would keep this thread updated with what I'm discovering. I talked to the local electronics person and he said that he would not be able to troubleshoot any issues with the ECM unless there were physical signs of damage. He did ask if my o2 sensors were good. I do have 2 codes for bad o2 sensors. Would bad o2 sensors cause the ecm to send the wrong signals and thus causing the car to not idle/misfire? Or should I just plan on sending in my ECM for repair? Can anyone recommend a good place to send my ecm on the west coast?

Thanks in advance for the help.

Harrison

[harrimann]

Well... I talked to some mechanics and he says that the ECM does not really go bad... I've read different. They are going bad all over the place. Is there a specific way to test the ECM? If I take the car to a mechanic is he going to be able to tell if the ECM is faulty?

Thanks again. I will def keep this post updated.

[harrimann]

So while talking to a company that repairs ecm i was told : Attention!!!
You will need to replace idle control valve (IACV-AAC) and throttle position sensor before installing your rebuilt computer, or computer will be damaged again"

W

[Buzzman]

Ok, first here is a link to the company I used to repair my ECM.
After I took out my ECM, I opened it up to have a look. There were no signs of any burnt components.
I have no idea what goes wrong.
When I got it back, the cover had a seal on it with a "do not open, warranty will be void" sticker.
I just put it back in my truck.

http://circuitboardmedics.com/nissan-ecm-repairs/

They did a good job, with a quick turnaround.
I re-installed the ECM, replaced my IACV (new OEM), did the relearn, and it has been running great ever since.

You didn't mention what codes you were getting. Can you provide those for us?
Also, you don't have to replace the TPS. Just the IACV. My TPS was fine.

Lastly, when I had codes for the O2 sensors (a few years ago now), it didn't kill my engine. It still ran fine.
I still replaced them to get rid of the codes, but I never had the kind of symptoms you describe.

Good luck, and get those codes posted up.

[harrimann]

I had three error codes, don't remember the exact numbers on the code because I cleared them from the computer.

1) High Idle Detected, Idle control valve fault
2) Bank2 Sensor 2
3) Bank 1 Sensor 2


I have the exact codes written down at work. I will update the post when I'm back in the office.

I read another thread about someone with a faulty ecu, they took it out opened it up and did not see any damaged components. When they tested it with a multi meter they noticed that some of the capacitors were out of spec (according to the values printed on the capacitors). Once they replaced the bad caps everything was good to go. Can anyone speak to this? I'm thinking of doing the same. The guys at Redwood Electronics said that if I can find the schematics they might be able to bench test the ECM, however they did not sound hopeful.

Thanks for the reply!

Harrison

[stylesjas]

Buzzman, If I replaced my IACV new and not the ECM, will the bad ECM take out the new IACV?

[Buzzman]

Buzzman, If I replaced my IACV new and not the ECM, will the bad ECM take out the new IACV?

In a word, no.
A bad IACV will take out the ECM.
A bad ECM will not take out the IACV.

If the ECM is already bad however, a new IACV will not work, and your truck will be exactly the same as before. No difference.
What happens is that the blown ECM cannot (or will not) communicate and operate the IACV.

The good thing is though, If you put in a new IACV and nothing changes, then you'll know for sure that your ECM needs repair.
If you're really lucky, a new Idle air valve will work, and you'll have dodged a major bullet. (but I doubt it. lol).

Keep us posted.

[stylesjas]

What a relief! I replaced the IACV, then, the high erratic got worse. Found a place in Georgia to fix my ECM for $140.00. Just got it back, but the repair place said that in addition to the IACV being replaced, the TPS needs to be replaced as well. I ordered a new TPS from Rockauto and I should have it by Tuesday. Hopefully, by next week Ol' Blue will be rolling right again.

[Buzzman]

I ordered a new TPS from Rockauto and I should have it by Tuesday.

Just a heads up re: the TPS. There is a mechanical adjustment on these things, so just make note of the exact position of the old one.
Check the FSM just to make yourself familiar with the adjustment/replacement.
Once you have all the new parts installed, you'll still have to do the relearn process.
After I installed the new parts in my truck, my idle was too high, and it generated a fault code (SES light on) for (you guessed it) idle to high.
I had a hard time trying to do the relearn like in the FSM.
I finally took it to my mechanic at the dealership, and he did the relearn for free in less than 5 minutes.
He cheated though....lol...he used his scan tool through the OBD port.
My engine has run like new ever since.

[atraudes]

Is the IACV and TPS something we should be replacing proactively, especially considering that the ECM can get taken out?

I've got a very slight idle issue where it feels like the idle is just ever so slightly too low. Not an issue, but something I've noticed. Based on what I'm seeing here I'll be replacing both next summer just on GP, but I'm sorta wondering if I should do it sooner than later?

[Buzzman]

If I knew then what I know now, then yes I would.
The IACV is not cheap, but compared to the hassles that I went through, and the time lost with no vehicle, I would have replaced them in a heartbeat.

[atraudes]

Word. If my credit card wasn't where it's at thanks to the summer projects, I would too. I guess I'll keep an eye on it.

[Buzzman]

"keeping an eye on it" wouldn't have done me any good.
Mine was a hard failure with no warning.
I was driving home from work when my truck stalled at a red light.
From then on I had to keep one foot on the gas pedal and the other on the brakes to keep it running when stopped.
My first thought was a MAF sensor, so I tried that first, with no difference.
Spent one hour's worth of labour on my techy to troubleshoot the problem, and that was when I got the bad news about the IACV and the ECM.
The rest as they say, is history.
It was not a pleasant process, especially for me as it happened in the dead of winter.
I was working on this thing outside, in -20C temperatures.

[atraudes]

Hmm, good to know.

Man I'm grateful for our comparatively mild winters

[stylesjas]

Well, I finally got Ol' Blue idling correctly, now I got code P0057 - Oxygen sensor/catalytic converter. I'm hoping that I need to just drive it for a little while so the computer can read everything right.

[harrimann]

So bad news

I sent the ECM off for repair and replaced the idle air control valve. The instructions on the refurbished ecm said to replace both the idle air control valve and the throttle position sensor. I replaced both of them and now the car idles smoothly (good i guess) but now when I give the car gas it bogs down... kinda makes a low grumble sound. Now I have 3 errors all pertaining to the MAF and I can't get the car to go above 2000 rpm w/o shaking terribly and making a growl sound.

Any suggestions? Replace the MAF? I kinda don't want to just run around replacing parts unless I have to. The three codes I now have are:
p0101: MAF or VAF A Circuit range/perf
p0102: MAF or VAF A Circuit Low input
p0103 MAF or VAF a circuit high input

Any suggestions?

[atraudes]

It sounds like the MAF sensor isn't plugged in (properly?). Replug it and see if that makes a difference. Maybe try replugging the connectors on the ECM. I don't know what you would check beyond that.

I had exactly the same experience not too long ago and I had simply forgot to plug it in.

If you're feeling gutsy and the local parts store has the part onhand, you could see if swapping in a new MAF sensor makes a difference.

[harrimann]

So the car won't go above 2500 RPM it appears as if the car is in limp mode? Everything is pointing to a bad MAF. So I guess I will replace the MAF unless someone else chimes in.

Yes I checked and I did remember to plug the MAF in. I also checked to make sure the ECU was connected correctly which it was so I'm going to say its a bad MAF. I'm having a hard time determining which brand is OEM. I was thinking about going with a Delphi brand.. any suggestions? Or any links as to where I can find one online. I'm thinking I just need the sensor itself and not the whole housing, as the housing seems to be fine.. any thoughts on that?


Thanks again for all the help. Hopefully I can get this baby back on the road tomorrow (if I can find the part locally)

[atraudes]

I'm fairly sure it's Hitachi, but Delphi makes great stuff. I'd order off of rockauto or Amazon, personally.

You don't need to buy a new enclosure; just a sensor. The sensor is screwed into the housing with 2 star hex screws. Just remove the screws and pull while twisting.

Before doing anything else, though, perform an Idle Air Volume Relearning procedure: post5937820.html?hilit=maf%20multimeter#p5937820 I think you need to clear the codes before attempting this. Buzzman was referring to this earlier.

A few things I can think of to check before replacing it:

- Disconnected hoses/leaks: post6606161.html
- Broken/frayed/shorted wires; test that the wires going from ECM to sensor are all still good using a multimeter or something of the like.
- Pull the sensor and check for contamination and clean with MAF sensor cleaner. Highly doubtful that's the culprit considering what you described doing, but there it is.

It's just weird that you would have all of these problems and to top it off, have an MAF sensor go belly up like that. I guess it could be attributed to the bad ECM though...

[harrimann]

Hello,

I would like to update my thread in case anyone else is having to deal with the same issue(s).

So I replaced the MAF with a OEM rebuild and now the pathfinder is running like a dream.

Thanks for all the help. I will report back in a few weeks/months just to verify that everything is still working as should.

Harri

[CanuckQx4]

I myself have an IACV problem , and multiple units from the junkyard havent solved my issue. I assume it is because I am self diagnosing and have never heard of this ECM issue.

Where is the ecu located on a qx4?? I dont really have the downtime to send my ECM out, Id need to either buy a new unit or a used one from a junkyard (which would be a crapshoot if they even have a working one as it doesnt like it can be "tested"

[harrimann]

The turn around time for the ECM repair was only a day or so + shipping time. It appears as if they replaced the mosfet(s) on the logic board. The ECM is under the steering wheel towards the center of the dash kinda right above the gas pedal.

I recommend you bite the bullet and just send your unit it to get fixed. The cost was 80$ plus shipping. If you know how to solder you could replace all the mosfet(s) on the board as well as the caps and see if that gets you anywhere.

What exactly is your vehicle doing? What year is it? I can send you a link to the place I used, they were in Georgia but there are places all over the country that can do it. I could not afford the down time either, but you are just going to have to do it.

[CanuckQx4]

Oh wow $80, much better than the $250 I just seen on ecu medics. I would greatly appreciate there name/link, I can take a few days downtime and get rides to work, but Im also in canada which would surely add a week to shipping times.

My 2001.5 seems to have a funny idle, and sometimes on initial startup it will stutter/bog until it has warmed up. I believe my IACV is bad though, as it seems seized when I had it out last ( this ecm problem is the first Im hearing ) Sounds like I need to replace both

[harrimann]

Yeah I had to replace both as well as the throttle position sensor and the MAF. Although I think the replacement of the MAF was due to me breaking it while repairing the other parts on the vehicle.

MyAirbags
2005 Boggs Rd
Duluth, GA 30096

678-778-8890


That is the company that I used, I purchased the "service" off ebay so you might want to check that.

[CanuckQx4]

Thanks bud I appreicate it, I bought a new MAF last year no issues with that

So you actually spent the $200 on an IACV and $65 (rockauto prices) for a new tps??

So about $400 all in to repair this problem including sending the ecm out eh

[harrimann]

No, I spent 100 on the IACV from Amazon (OEM), and then the maf was 120 and the tps was 80$. This is all in the US, I'm not sure what your prices are going to be up there. But yeah I ended up spending about 400$ or so. I did not really have a choice. The mechanic wanted way more than that. They wanted 1200$ for a rebuilt ECM then they watned 550 for the IACV. Loco.

[CanuckQx4]

I know Im asking alot but could you link me to that $100 IACV? I dont see one on amazon and that is a hell of a deal I will buy that tonight for sure, I have a US shipping address so I ship things there and make a run a few times a year to pickup parts (i live close to usa/canada border)

Why do you think they require a brand new TPS?