QX4 Stalls when coming to a stop. Idles sometimes then dies again

[snufalufagus]

Hello guys. Long time lurker here. Now before I am blasted for asking this question I have read until my eyes bleed on what to do and made it to this point.

So probably a coincidence, but I got in one morning and my low fuel light was on. Drove straight to the gas station and filed up, about a mile down the road she died on me. Started back up and made the rest of the 6 mile trip in to work. Went out to lunch, about a 6 mile trip with no problem. On my way home about half way I could tell she was going to die. When on the gas she drove as normal but let off the gas to coast and the idle started to drop more and more each time until she started to stall out every time. Limped her home using both feet to keep the revs up. Over the next 2 days I tried to start it multiple times. It would start and immediately die. Keep in mind all the while NO ERROR CODES. I did my research and had my plan of attack.

Fast forward to the weekend. First thing I tried was replacing the fuel filter. Afterwards she started right up and held idle. I thought no way could that be it. Let her sit for about 3 minutes and jumped in for a test ride. about 100 yards down the road while costing down hill the idle started to drop and died. Turned around and limped it home.

Next I removed and cleaned the MAF sensor, and checked to make sure the computer was sending voltage. Put her back together and had a CEL for MAF, cleared it. Started her up and she idled fine. Took her for a quick spin. about two miles in, idle starts to drop and she dies. I limp it home using two feet.

Then on to the Idle Air Control Valve. Checked it for voltage from ECM. All checks out good. Pulled it and ohm'd it out and it checked out good. Plugged it in and did a visual inspection to make sure it was moving and it was. Cleaned the Throttle body while I was there. Put her back together and she started right up. This time I let it sit and idle for about 4 minutes until........you guessed it. Idle starts to drop and she dies.

Where do I go from here as I figured it would be the dredded IACV/ECM failure but that doesn't seem to be it?!?!?

[atraudes]

First off, that is some excellent troubleshooting!

It is really unfortunate that you aren't getting any codes and I concur that it probably isn't your IACV. The thing that comes to mind is fuel because fuel issues generally don't throw codes. See about getting a fuel pressure gauge and hooking it up to the fuel rail. You should be able to rent one from a local car parts store. It would be really useful to see what the pressure is at idle, how long the pressure is maintained after shutting it off, and what it is after it stalls out. Depending on what you find, it could be a handful of things.

[snufalufagus]

Atraudes, Thanks for the reply. I will plan on sourcing one for the weekend and give your suggestion a shot as I am trying to get this figured out as I really have no money to bring it to a shop. I did also add some Lucas Fuel treatment to the fresh tank of gas when I replaced the fuel filter.

Any other suggested courses of action?

[atraudes]

It couldn't hurt to pull your spark plugs and see if there's anything unusual there, though I'm expecting not. Also, pull the vacuum hoses off your fuel pressure regulator and fuel damper while it's idling for a few minutes and see if any fuel comes out of the vacuum ports on them. I'd also check your intake boot and look for cracks or tears, especially in the seams.

[snufalufagus]

Noted. I will add all that to the list.

I just spoke with an Infiniti Tech on the phone I was referred to. Giving him the sypmtoms he suggested even though the IACV checks out good he feels that is the issue. He suggested I replace that and see what happens. He even offered for me to come by and he'd do the idle relearn. Good to know people I guess. My question is this, he of course suggested OEM but I can get a Hitachi on Amazon Prime for $95. Does anyone have any insight on these or aftermarket not working in general?

He of course noted to keep fingers crossed that it didn't burn out the ECM.

[snufalufagus]

Just quoted $300 for OEM from Infiniti. Thinking about giving the Hitachi a shot.

Just found your old post that you said you used Hitachi. HITACHI IT IS.

[atraudes]

The only reasons I don't think the IACV is at fault is that it's not throwing a code and it doesn't die consistently. All of the experiences I've read from others on the matter is they always get a code thrown and they can't get it to idle at all. However, yours could be dying in a different way or maybe you've caught the early death rattles.

That being said, if you're up for buying a new one, I say go for it. The symptoms do suggest it as a suspect, and it's a part that is well known to fail on these vehicles, causing expensive repairs. I replaced mine as a preventative measure, so I think it'd be prudent either way.

Yep, as best as I could tell, the Hitachi is the OEM part anyway. I'm still having zero problems with mine.

As for the idle relearn, I doubt it'll make a difference at the moment since you aren't having a consistent idle issue. You will want to perform it when you get the new valve installed. It only takes a few minutes and is really straightforward. The steps are in the FSM and around here somewhere.

[snufalufagus]

That is what the Tech said. In his experiences he said that is where he would start. He thinks it's just been caught early and even though it's ohm'ing out correct it's still starting to fail. Part will be in tomorrow and I will report back, hopefully with good news.

[miamiheat3332]

Got the same issue on the Pathfinder last week. Idles fine when cold but once warms up cannot hold idle. Revs fine and can be driven (drove it over 15 miles on highway) however when you let rpms drop it dies time after time.

Ordered a new maf off amazon, still getting same issue. I know maf is working, unplugged it and wont idle as well, however unplugged wont rev past 2.5k rpm.

Im really ruling out fuel and spark issues because of it being driveable, if it was a pump etc would have been dead.

I ordered the hitachi iacv and gasket off rock auto (2.50 gasket, $86 for the hitachi). Im thinking thats the issue... Will report back as well.

[miamiheat3332]

Adding to last post, i have code p1102 now however first time around had that and p0506, which points to me is iacv. Hopefully thats it for both of our vehicles here.

[Buzzman]

I had the same symptoms start on me about two years ago.
I hesitated to replace the IACV right away, and it cost me a blown ECM.
If I had followed my gut and just replaced the valve when the problems started, I wouldn't have had to go through the ECM repair nightmare.
These R50's are getting older, and these IACV's are failing more and more.
Bite the bullet and replace it right away.
Don't forget the relearn when you're done.

[atraudes]

Im really ruling out fuel and spark issues because of it being driveable, if it was a pump etc would have been dead.

I wouldn't rule it out completely. Fuel pumps can deliver some weird ups and downs in terms of pressure before they actually give up the ghost. The only way to be sure is to see what the pressure is when it dies.

I'm looking forward to hearing how the new valve works out, and have my fingers crossed. It'd be nice if the fix was that easy. The IACV is a lot easier to swap than a fuel pump.

[QX4Cameo]

yeah you don't want your car throwing p0505. Change out the IACV soon. It also wouldn't hurt to pull the ECM first to see if you have the death smell (quick pull to check 20mins tops) fix on the ECM 100-120 ebay.

[snufalufagus]

MH3332, Here is to hoping both of our issues get solved with this fix.

The tech I spoke with just talked about replacing the motor with plunger and if ordered through Infiniti it sounds like that's all you get. Reading it seems like it's a huge pain to get off the whole assembly not to mention I didn't order the gasket for it. Is it necessary to replace the whole thing or do you guys see an issue with just replacing the motor/plunger?

[miamiheat3332]

Forgot to post here the other day when i got the iacv and installed it.

That was the fix, perhaps it was a combination of the MAF since it is the new one from amazon in there now, regardless all is working and i did the idle relearn procedure from the fsm EC-71.

[snufalufagus]

Same here as MH3332. Replaced the IACV and she is up and running again. I guess at least now I have a new Fuel Filter, Clean MAF and clean TB to go along with it. I haven't done the Idle Relearn yet? It seems to be functioning normally though? Should I leave it alone or get it done?

Going to do some more preventative Maintenance soon to hopefully keep the old girl good for a while.