My 2001 pathy stumbles strangely

[spaceman]

Hello everyone, since I first owned it in 2005 my 2001 Nissan Pathfinder misfires during engine warmup. It had 78,000 miles when I got it, now it has 125K miles.

Here's the symtoms: Runs fine first 5 to 7 minutes, then goes from smooth running to rough for about 30 to 40 minutes, also strangely affects transmission in overdrive but has no transmission affect in normal drive. Finally, after shutting engine off for about 5 - 10 minutes all is normal. No engine roughness, no transmission trouble. This problem began to show when the weather was cool, now its all the time. Checked with my code scanner, during rough period I get a P0300 code - multiple misfires - and 'no troubles' after it runs smooth.

Strange, huh?

What is likely wrong with the car?

[Adnan]

does it have a ups truck feel to it?its a problem mine develloped day 2nd day after i picked it upreplaced the spark plugs and its now buttery smooth

[spaceman]

It stumbles but in relation to engine temperature changes along with the outside weather, like in dry warm air it will run mostly smooth all the time, in warm humid air in runs rough but only during a range of time. In cold air it creeps back even with low humidity. As I said in the first 5 to 7 minutes it's fine, from the 8th minute to about the 40th minute it's rough. Then for some reason when I pull in somewhere and shut the engine off for a few minutes and then start it it runs fine. Stays that way until it has sat for more than 2 hours. I've been looking and asking a lot of questions on line and I get the feeling that it may be my mass air flow sensor or it may be the air temperature sensor. The spark plugs had already been changed recently along with having the injectors cleaned and that did not help.

[pathfinder9035]

i had a similar problem but i just fixed it today! yeah!... it is very common with 2001 pathfinders and qx4. the coils go bad. so what u need to do is iether change all the coils and sparks or take it to nissan to figure out which cylinder it is comming from. i took it to advance auto and i got P1320 and another code saying cylinder 2 was misfiring. i replaced cylinder number two coil pack today and it is normal now and driving great. if u got the tools and hands do it your self. pretty easy job except for cylinder number 4 and 6 which is hard to get to. but yeah its your coil packs from what i experienced. i reccommend just going ahead and replace all 6 coils and sparks so u dont have to worry about in the future,good lucck

[Pathy-D]

I totally agree. I had a similar problem and my OBD reader couldn't figure out which cylinder was misfiring at first, so I replaced the three coils on the side furthest from the air filter and then the reader finally said it was #2 cylinder, so I ended up replacing 4 of the 6 coils. So far so good, but the other two will probably go sometime here, so if you have everything apart, replacing all six is a good idea.

Immediately prior to that, I had to replace my MAF as well. My pathy would lose power for a few seconds when going uphill and then surge back to life. I bought MAF cleaner from an autoparts store and sprayed it, which helped for a bit, but then the problem came back. I bought a used MAF from an autowrecker for $200 (the dealer wanted $620), put it in, and I haven't had any of the same issues since then.