Engine issues

Tiny
MICHAELR1870
  • MEMBER
  • 1997 NISSAN PATHFINDER
  • V6
  • 4WD
  • 120,000 MILES
It will start bucking and jumping at any acceleration over 2900 RPM every time you try.(When being driven). It also has a slight high idle issue. Note: that when accelerated to the floor it sometimes backfires and seems as though it is struggling for fuel. (Parked) Mike. 1987 Nissan pathfinder. Sorry
Saturday, November 17th, 2018 AT 10:53 PM

5 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Good morning.

The first thing that comes to mind is a clogged catalytic converter. If the engine is not allowed to breathe correctly, this is a result.

A back pressure test will confirm. The O2 sensor before the catalytic converter has to be removed and a gauge inserted to measure pressure. Anything above 1.5 lbs. is no good.

Also, how old is the timing belt? Valve timing being off can produce this issue as well.

When was the last time you had a tune up?

Roy

https://www.2carpros.com/articles/engine-backfires-while-running

https://www.2carpros.com/articles/how-a-timing-belt-works

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

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Sunday, November 18th, 2018 AT 5:36 AM
Tiny
MICHAELR1870
  • MEMBER
  • 10 POSTS
I have put a new timing belt on fairly recent although it is possible I may have gotten off a notch. If I did, would it cause this? I drilled holes in the catalytic converter also. So what now? Thanks, Mike
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Sunday, November 18th, 2018 AT 7:44 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Drilling holes is not enough. It is more more area to breather if that is the issue. Try removing it and see if it is better.

Yes, if you were off a tooth, it would do this as the valve timing would be off.

Roy
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Sunday, November 18th, 2018 AT 7:48 AM
Tiny
MICHAELR1870
  • MEMBER
  • 10 POSTS
I know I get the same results on RPM's parked (2900)easing into the accelerator as I do on the how at. 2900 TOM's both ways when the problem starts. It is off a tooth. Would that be your opinion also? Mike
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Sunday, November 18th, 2018 AT 8:16 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Yes.

I would start with the catalytic converter before going to the timing belt.

Roy
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Sunday, November 18th, 2018 AT 8:18 AM

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