Engine chugging/hesitating while off-roading

[richardekirby]

Last week we went to SW Colorado and did some off-roading. The pathy performed very well except for two times when the engine starting chugging and hesitating. Both times it happened while we were on a steep climb up and over 11,000 ft. I was able to reach a safe spot and stop. The enging never died and was not running rough. It went away when I started climbing again and the incidents were on two different days. Anybody ever have this happen?

[NVSteve]

Last week we went to SW Colorado and did some off-roading. The pathy performed very well except for two times when the engine starting chugging and hesitating. Both times it happened while we were on a steep climb up and over 11,000 ft. I was able to reach a safe spot and stop. The enging never died and was not running rough. It went away when I started climbing again and the incidents were on two different days. Anybody ever have this happen?

I haven't had it happen in the Pathfinder yet & I'm often over 11,000-14,000'. But, I have had this happen in a past vehicle due to a not-so-clean air filter.

I know in the old days, vehicles meant for sale in places with low elevations were tuned differently than vehicles meant for higher elevations. I have absolutely no clue if this still applies, but you would think the on board brains would be able to account for elevation gains (lower oxygen levels, etc.). Maybe they are tuned when they arrive at the dealer for elevation. I know when I drive at lower elevations, the PF is like a rocket. Cars I have rented in low elevations all seem to have struggled when driving up to higher altitudes. I'm only rambling at this point. Hopefully some of the guys here who wrench daily have some real answers.

[richardekirby]

Last week we went to SW Colorado and did some off-roading. The pathy performed very well except for two times when the engine starting chugging and hesitating. Both times it happened while we were on a steep climb up and over 11,000 ft. I was able to reach a safe spot and stop. The enging never died and was not running rough. It went away when I started climbing again and the incidents were on two different days. Anybody ever have this happen?

I haven't had it happen in the Pathfinder yet & I'm often over 11,000-14,000'. But, I have had this happen in a past vehicle due to a not-so-clean air filter.

I know in the old days, vehicles meant for sale in places with low elevations were tuned differently than vehicles meant for higher elevations. I have absolutely no clue if this still applies, but you would think the on board brains would be able to account for elevation gains (lower oxygen levels, etc.). Maybe they are tuned when they arrive at the dealer for elevation. I know when I drive at lower elevations, the PF is like a rocket. Cars I have rented in low elevations all seem to have struggled when driving up to higher altitudes. I'm only rambling at this point. Hopefully some of the guys here who wrench daily have some real answers.

The air filter is fairly new and clean. I'm sure it was the computer mixing things up. To fix the problem, all I had to do was stop then it was ok to proceed. Sometimes that's a little difficult when you are in the middle of a steep climb with a 1500ft drop off only a few feet away.

[Captain]

The reason alt makes a difference in engines is from the low levels of 02. The ecm learns whats normal for its idle and daily driving. when you suddenly go from 500ft to 11,000ft the 02 is increadable less and the engine is still wanting to un for 500ft and is over fueling causing it to run sluggish till it learns ( mostly after 10 starts or 10min) then it recalibrates for the new 02 setting. I realy noticed this with me living in Laramie, Wyo and driving to Chicago about once a month for a year with my POS chevy.