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96NP - occasional random stall at idle


Wifes96NP
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96 Pathfinder with 200k+ miles

 

No ECU reported faults

 

When car is fully warmed up and idleing (like at a traffic stop) it suddenly stalls. Happens maybe just several times in one hour. I have been unable to duplicate this problem with harness shaking, component tapping (knocking on MAF, etc) and think that maybe the fuel pump is going out.

 

Anyone recognize this problem?

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Years ago my Pathy would stall when I came to a stop, and I could only keep it going if I put it in Neutral as I approached the stop and kept the idle high.

It was behaving a bit like a stuck EGR valve.

 

Turned out to be a cracked ignition coil if I remember correctly.

It doesn't seem intuitive that a failure like that would have that symptom, but it did...and the tech who fixed it was flabbergasted too.

 

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Thank you, I will check the coil. Not familiar with these old distributor types, but I'll refer to my FSM to guide me. It somewhat makes sense as the dilute, lower pressure mix is difficult to ignite and more sensitive to detect.

 

Confident it is not the EGR system because I had to replace the valve for being cracked, and it stalled with cracked valve installed, new valve, and even with system capped and disabled for awhile.

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Sounds like it could be the crank or cam angle sensor. Unfortunately the CAS and coil are built into the distributor. If either one fails you have to replace the whole distributor.

Or it could be the idle valve. Does it start up fine in the morning after it's been sitting for a while?

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Or it could be the idle valve. Does it start up fine in the morning after it's been sitting for a while?

It starts and warms up fine.

 

Just randomly when driven for 10+ minutes does it stall (noticed at idle). It happens only occasionally, sometimes not at all for a day or two, but when it does it will rumble, stall or loose ignition all together. It is not associated with hitting a bump or vibration like a wiring problem would behave. It acts like a system that is used only at a certain threshold is causing it to fail.

 

ECU has no idea it is malfunctioning either

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I will order a distibuter since it's only just over $100 the car has 200K miles.

 

If that doesn't fix it I'll look in to the idle/TB area

 

 

I'lll report back with the news, thanks for the help eveyone!

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Just replaced the distributor in mine, it was doing the same thing. At lights it would idle really rough, lose power and sometimes stall. Got to the point that it would buck while driving too.

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Just replaced distributor. Did not fix it. Interesting thing I noticed was the old distributor was rotated almost full advanced (like it was set this way by the mechanic I recently had change the belts), now using a timing light as such the yellow mark is timed spot -on with it set like this.

 

My question is, if the timing belt was off a notch or so, would the distributor need to be pegged in adjustment to get timing back 15 BTDC. Before I removed the distributor, judging from the factory marks the adjustment bolt scored on the surface, it was recently tweeked to that setting which was just after the timing belt was changed (and we had the vehicle since 1996 so it couldve been no one else).

 

Edited by Wifes96NP
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If you put the distributor off one tooth then you might have to peg it to one side to get the correct timing. Might happen also if the timing belt is off a tooth but it won't run smoothly.

Check the intake for air leaks.Idle control valve..etc

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Thank you for the leads, Beatup96 and rick88ss

 

 

 

The problem with the car is totally intermittent. Has two modes of operation: "Normal" and "weak". Seems like if it goes to weak mode while idling it will die, but it CAN maintain idle once in the weak mode. However it's just my perception on what's going on.

 

Two questions

 

Would an idle control valve cause poor acceleration too?

 

Will MAF problems create intermittent symptoms?

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My cracked MAF was similar to what your truck is doing , if I came to a stop it would stall if I didn't keep my feet on the gas and the brake while stopped .

My mechanic found a hairline crack in the MAF "housing" (for lack of the correct term) , being a friend he tried to save me some $$$ and put some "goop" on the crack .

He drove it around picking up parts , lunch , etc... and it was fine for a while before the stalling came back , the "goop" had separated after drying completely .

New MAF and it never did it again .

 

May or may not be the problem you're having , but checking for cracks is free.... :lol:

 

My distributor went boots up a few years back but never gave me stalling problems , it bucked a few times and then just crapped out .

I can't comment on the relationship between the timing belt and distributor positions though .

 

Fuel filters are cheap , I'd change it and see what happens as it's due anyway .

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I haven't had to adjust my TPS but it should show the proper procedure in the FSM or it might be on this forum. It should have two sensors in the TPS. One switch to show idle or not idle and a variable voltage according to throttle angle sensor.

I bought a code reader/scanner from the auto parts store that will show the idle and throttle open percentage on the little screen. It'll also read the check engine light codes.

Edited by rick88ss
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With a timing light on, and TPS sensors electrically disconnected,

Where should I time it?

 

On what mark that is, looking down from radiator (1 thru 5 as left to right) :

 

| | | | |

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Two problems:

1) left bank cam was advanced off time - fixed. This caused the knock sensor and ECU to go nuts

 

2) MAF is bad, likely the cause of the random stall. I removed the plastic on top, exposing the center pin's wire connection. it was loose. Much too small for me to solder so I just bought a new one

 

 

Car finally has some torque, I mean more than it did 19 years ago new. It has some life to it

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