2001 Pathfinder LE starts but stumbles

A forum for the legendary Nissan Pathfinder and Infiniti QX4.
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microfiz
Posts: 4
Joined: Sun Mar 03, 2019 9:53 am
Car: 2001 Nissan Pathfinder LE

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Some background:
I purchased a 2001 PF LE (3.5 L) 1 1/2 years ago and logged 35000 uneventful miles. She now has 200K on the odometer.

A couple of weeks ago, she started having starting issues. The first start would usually involve a stumble and then stall. Restarting and giving it a bit of gas made it run normal... but it progressively got worse to the point that it would now start and high idle around 1200 rpm for a couple of seconds and then bog down.

So I took in the garage and just tore into it (needed to change the valve cover gasket and inspect the power valves anyway). Also ohmed the IAC valve (checked out good). Put everything back together and it was still the same. I figured maybe the pump and fuel filter are done after this high mileage so I replaced those but still that didn't help. I haven't checked the crank position sensor as another member suggested on another thread, so that's what I'll do next. Anything else I need to check? I looked at the old records and it seems like the PCM on this car was replaced along with the IAC valve early in it's life (around 100K miles ago).

Any tips would be greatly appreciated.


04pathse
Posts: 776
Joined: Sun May 02, 2010 2:55 pm
Car: 2004 Nissan Pathfinder SE
2008.5 Mazda Mazdaspeed 3

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no check engine light/trouble codes?

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microfiz
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Joined: Sun Mar 03, 2019 9:53 am
Car: 2001 Nissan Pathfinder LE

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No engine lights, no fault codes (current or pending).

I could rev it up momentarily but it bogs down by itself. So with the throttle open, a malfunctioning IAC valve should not have any effect (which I have ohmed already). There's fuel (new pump and filter) and spark (new plugs too) so something isn't synching. And again, it started off as a rough idle on first start but over the course of a few days it became worse. As of now, I can start it, it will high idle for a couple of seconds above 1K rpm, and then bog down and die.

04pathse
Posts: 776
Joined: Sun May 02, 2010 2:55 pm
Car: 2004 Nissan Pathfinder SE
2008.5 Mazda Mazdaspeed 3

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could be the fuel pressure regulator or fuel injection system dampener, you can do a search on this forum for more info on it

heavy hitter
Posts: 90
Joined: Thu Dec 20, 2018 2:36 pm
Car: 2001 QX4

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check the maf and tps sensor also

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microfiz
Posts: 4
Joined: Sun Mar 03, 2019 9:53 am
Car: 2001 Nissan Pathfinder LE

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Just seems odd that this thing does not generate a code (I removed the TPS connection for example and it did not generate a fault code).

My W21 which had pre-OBDII even told me it had a bad injector.

I'll probably borrow our work O-scope and check out waveforms for the crank sensors as well as follow the other advice I got/read here.

As much as I'd rather not shotgun this thing and make very educated guesses, it looks like I'm getting to that point. Just a bit frustrating that this thing was flawless and all of a sudden (well, in the span of a few days) starts crapping out and not even giving any fault.

04pathse
Posts: 776
Joined: Sun May 02, 2010 2:55 pm
Car: 2004 Nissan Pathfinder SE
2008.5 Mazda Mazdaspeed 3

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an extremely dirty MAFS might cause the issues you are having so cleaning it would be a good place to start, only takes a few minutes to do. Best to use CRC mafs cleaner, some have used dechlorinated brake cleaner to clean them if you happen to have some of that around.

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microfiz
Posts: 4
Joined: Sun Mar 03, 2019 9:53 am
Car: 2001 Nissan Pathfinder LE

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04pathse wrote:
Thu Mar 14, 2019 1:30 pm
an extremely dirty MAFS might cause the issues you are having so cleaning it would be a good place to start, only takes a few minutes to do. Best to use CRC mafs cleaner, some have used dechlorinated brake cleaner to clean them if you happen to have some of that around.
That's odd. I thought I replied to this (but it's gone).

ANyway, thanks for insisting I check the MAF. I actually thought I pulled the connector on this earlier as a check, but I guess I pulled so many that I missed this one. Anyway, it was a faulty MAF. I pulled everything again and as soon as I got to this, it idled perfectly (PCM reverted to default values) and a fault code. I tried to clean and re-install but the condition came back. I'm buying a replacement today.

Thanks again!

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paranoidjack
Posts: 1417
Joined: Mon Oct 03, 2005 3:57 pm
Car: 2012 M56s
2003 M45
2001 QX4
2000 Q45
1998 Pathy
1996 J30

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Beat me to it - replaced my MAF the other day. By the way, hope you ordered the 2001 Maxima one. It is the same part # and much cheaper. Some folks also say despite being the same part #, it is "better." I don't know if I buy that, but it IS cheaper. Replaced mine on my 2001 QX4 last week and addressed alot of BS with idle, rough, etc.


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