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2001 QX4 intermittent stalling on startup


urbpath
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I've read so many different articles with different ideas of what this issue could be.

My 2001 QX4 stalls on start up very randomly. It could be hot, right after driving. Or after sitting overnight. It will do it very intermittently. I've done the relearn procedures. I have gotten the SES light twice now. The code was for idle air; I believe P5505?
Work done so far:
-replaced IACV, TPS, MAF
I was thinking if I should replace the alternator, check vacuum hoses, and compression test, and maybe fuel relay and fuel filter.
Please help!!
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Sounds like it could be a fuel issue. Either an extremely clogged filter or a weak pump. Get a fuel pressure gauge and check your pressure during prime and then again when it's running. I think fuel pressure should be somewhere around 46psi at idle. You want to hook it in after the filter to get a good reading.

 

Check and replace all your vac lines if they've never been done, I've found some really bad ones that looked perfect before removing them that we're the source of some pretty serious air leaks.

 

If it were a bad alternator it would still start and run but the battery would slowly drain due to lights and other electronics draining down.

 

 

 

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Ok makes sense. Thanks!

 

Ive actually just found out I have the fuel filler tube recall to do. I wonder if that has anything To do with it?

 

 

Edited by urbpath
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I'm not familiar with that issue but I'd still look into if it hasn't been done, it's always a good idea to keep your tank sealing and venting like it should be. Vapor leaks could be a fire hazard and obviously fuel prices are getting up there.

 

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No way is it the alternator. If it runs fine once it's going, you can rule out compression and probably the fuel filter too (though if you're gonna shotgun parts at it, fuel filters are cheap). I'd expect a leaky fill tube to throw evap codes (though if you can get a new part under warranty, do it anyway). Vac lines are cheap and can't hurt, though I'd expect a vac leak to be a constant issue, not an intermittent one. I'd be surprised if it was the fuel relay, though I have to say it's not out of the question... if the fuel pump isn't getting power, the engine would die once the fuel pressure left in the lines drained down. I'd try to start it with the fuel pump fuse out and see if it starts and stalls like what it's been doing. I'd be surprised if that was it, but it can't hurt to rule out.

I have read about an issue where a bad IACV fries part of the ECU (I'm assuming you've got the 3.5), which then can't drive a new IACV to make the engine run right. But then I'd expect it to idle poorly all the time, not just stall on startup, so that doesn't make sense either.

 

Intermittent issues really are a PITA.

 

 

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No way is it the alternator. If it runs fine once it's going, you can rule out compression and probably the fuel filter too (though if you're gonna shotgun parts at it, fuel filters are cheap). I'd expect a leaky fill tube to throw evap codes (though if you can get a new part under warranty, do it anyway). Vac lines are cheap and can't hurt, though I'd expect a vac leak to be a constant issue, not an intermittent one. I'd be surprised if it was the fuel relay, though I have to say it's not out of the question... if the fuel pump isn't getting power, the engine would die once the fuel pressure left in the lines drained down. I'd try to start it with the fuel pump fuse out and see if it starts and stalls like what it's been doing. I'd be surprised if that was it, but it can't hurt to rule out.

 

I have read about an issue where a bad IACV fries part of the ECU (I'm assuming you've got the 3.5), which then can't drive a new IACV to make the engine run right. But then I'd expect it to idle poorly all the time, not just stall on startup, so that doesn't make sense either.

 

Intermittent issues really are a PITA.

 

 

 

 

Couldn't agree more. I've had a hell of a time trying to figure stuff out. IACV has been done - OEM part used. ECU was replaced by previous owner...unless that's fried again... MAF replaced and tube cleaned...

 

Once in a while after starting, the idle will spike roughly and it will hit 2000-3000 rpms quite violently. I have to shut it off and start it again.

 

I'm running out of options and money...

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