'99 Pathfinder Bucking

[1999 DesertRunner]

Absolutley no recent problems...and putting a lot of miles on it. But, about a week ago, with about 160k miles, it started bucking, the tachometer would jump up and down...lost power, it would recoup and run ok, but a block or two later, the same..the tachometer bucks up and down..it seems like it was getting gas alright. I went over to a buddy and looked things over...found the air intake-elbow was cracked from heat/age and sucking air in. Found the part and waited a few days to get it delivered. Replaced it, cleaned out the soot...it ran fine for about 30 minutes and took it on the interstate and again, started bucking.. I hobbled home down side streets.

Its not throwing out any codes.

Could it be the cat converter, or the distributer, or something as simple as a dirty fuel filter?

[smj999smj]

You really can't tell anything without doing some tests, but I normally associate bucking with an ignition problem. Check the plugs, wires, distributor cap and rotor and check for play in the distributor shaft, first. If you replace anything, stick with genuine Nissan or NGK parts.

[Hans2112]

I think you and I may have same issue. Please, if you discover anything post it. I will do likewise. Good luck

[1999 DesertRunner]

About a week after posting, I took it out again, and it was worse, sounded 'contsipated', and still bucking. I took out the cats....it ran okay, up to around 35mph, but started a backfire and again bucking..tjhere was a sound like bb's rolling around in the muffler, but just pieces of the cat guts

So, did/had the following done: fuel filter, and it ran a code for the knock sensor. Changed that out, and also since I was at about 160k and never knew if the timing belt was changed, had that taken care of, along with the water pump, other belts, radiator flush, etc...the timiing belt was original, and then found out, it never had a tune-up, with plugs wires etc...while the distributer was out, with the intention of just putting on a new cap..found the shaft was binding and small shavings came out...a bad bearing or something else, but not a good sign..so, changed that..

Its running gereat now.

I couldnt isolate what the cause was...maybe it could have been just putting in a new distributer...and could have saved the cost of the knock sensor, etc...but, it was long overdue for a tuneup, and of course, the timing belt!

[Hans2112]

Yep, sounds like I need to do about the same routine. What was your grand total???