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Momentary loss of ignition (?) during long stints on freeway


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Hi everyone,

 

I've to 170k on my Pathfinder and just noticing a problem that's getting more persistent and deliberate. If "feels" like the engine is losing ignition for a split second. Sensation is felt through the drivetrain as power is momentarily lost then regained...a little jolt.  I noticed it a lot during my last trip between WI & Illinois, was nasty cold, wet, & rainy. I'm hoping to avoid getting stranded as I do this commute 4x's a month! *During a 3 hour round trip I felt this about 20 times.

 

Note: No engine light, my OBDII didn't show any stored codes. Truck does have a remote start which might be a potential item to consider. 

 

Any thoughts greatly appreciated!

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Does anything else go out when it misfires? Lights, gauges, radio? Could help narrow down what's flaking out. I'd expect the key switch to override the remote start and make it irrelevant, but I don't know how it was installed. Would be a good thing to check first, make sure the connections are good. If your scanner supports it, I would also check for pending codes (in case it knows there's an issue but can't be arsed to tell you yet), and (with the engine off) check your throttle position sensor by watching the live data while slowly pressing the pedal. If the sensor's got a dead spot right around where you hold it for cruising, it could be telling the computer to let off when you don't want it to, though IIRC drive-by-wire typically has two pots in the pedal sensor and codes if they don't agree.

 

If you haven't done the trans cooler bypass or replaced the original radiator, I would check it for signs of SMOD as well. Doesn't sound like that's what's going on, but I'd check it anyway. See if the gasket for the rad cap is swollen, there's mayo-looking schmoo floating in the expansion tank, or there's what looks like pepto-bismol on the trans dipstick. Like I said, long shot, only mentioning it because it's a common R51 issue.

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Hey, thank you for that response. I think the TPS thoughts are interesting, and maybe that would make sense of no error code. I've had cars in the past that haven't thrown codes for that. Driving at a very steady pedal position for long periods of time might emphasize such a condition, I'd think. I'll do some homework!

 

Thanks again~

 

Dan

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I had a similar issue on my 04...not that these systems share anything, though.  But same symptoms: just steady throttle and then a random occasional throttle surge/hesitation.  Would also happen when using cruise control, and was enough to cancel cruise.

 

Mine did throw some "A-B" throttle position codes sometimes, but not always.  "P2135" seems to ring a bell.  The blips would occur regardless of code thrown (I don't recall checking if codes were pending).  In the end, I pulled the throttle body off and cleaned it thoroughly.  I went a few extra steps of drilling out the rivets on the cover and cleaning all electrical contacts inside.  I probably wouldn't recommend going that far, but basic cleaning might not hurt.

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Hey, thanks for that reply. Yes, sounds exactly the same as your experience. My Pathfinder also does that using cruise control. Thinking back, I purchased this with a torn intake boot so there's a good chance that contaminants made it inside those components. I'll give that a shot!

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