Greetings!

I'm new here, hoping for some troubleshooting advice. About 8 months ago, I purchased a used Xterra and have had no problems with it until last weekend.

The truck is an '02 SE S/C, 4WD, 5 speed, 123k miles. While in 4LO climbing a pretty rough hill, the truck suddenly lost power and would barely idle, wouldn't rev. I was only halfway up the hill, so I shifted to neutral and let the truck slowly bounce back down the hill. By the time I got to the bottom of the hill, the truck was idling normally again, but the exhaust seemed louder than normal. I got out and looked underneath, noticed a small hole at the muffler inlet.

On the way home, I was unable to accelerate in 1st gear beyond about 20% throttle without the truck surging/bucking fairly violently. 2nd gear isn't as bad, and higher gears don't seem to exhibit the problem. If I drive the truck using less than 20% throttle, you'd never know there was anything wrong with it; smooth acceleration, and it ran at 70 mph on the freeway all the way home with no problem.

My initial thought was a partial clog somewhere in the exhaust, but the muffler guy I've got looking at the truck doesn't think so. I'm getting a new muffler tomorrow anyway, and he'll give the rear cats a peek while he's in there, but I'm wondering if I should be looking somewhere else.

I should also mention that the CEL hasn't lit during any of this, but it does function. Timing belt, spark plugs & wires, O2 sensor, and a few other tuneup related items were changed 8 months ago. I use only 91 octane gas.

Thank you in advance for any and all advice.

steve lyon
Los Angeles, CA

First thing is to see if there are any codes.

One possibility could be on the air intake. Check the MAF sensor and the intake tube from the air filter box to the engine. A dirty or bad MAF sensor could produce the symptoms. Also, a crack in the intake tube resulted in very similar symptoms on my truck. (If the intake tube is cracked, also check for a broken driver side engine mount -- that was the cause of the crack that I had).

k_enn

Thanks, k_enn. I will give the MAF and intake a close look.

I forgot to mention in my original post that the only code pulled from the truck was a "misfire" code.

Just a repair update in case anyone searches on this problem in the future. The intake boot had a 1" long tear/hole on the underside - not easy to see. New boot was $28 and took about 15 minutes to swap out.

My engine mounts seem OK, but the boot/tube's rubber itself was dried out somewhat; the new part is a lot more pliable. I suspect the old one just cracked from age and heat.

Oh, and thanks to k_enn for the tips!

I've got nothing to add I just think this is the best problem solved post I have seen in a while.

Question, possible answer, correct answer, fixed, update... BOOM GOES THE DYNAMITE!

(funny how cars work. you would think it getting MORE air would make it better but no...)