Need help troubleshooting 98 pfinder that wont rev properly

[woodc]

I just purchased a rough, high mileage 98 Pathfinder SE automaitc 4x4 that needs some work.

The engine starts and idles OK (it has a slight stumble once in a while, especially once it has warmed up) but it will not rev past about 3K RPM before it just falls on its face (this is in Park, not under load) and sounds like it is bogging...it will not rev all the way up period. Lower RPMs however...just dipping the gas pedal for example, seems to work as expected.

I plan on starting with the low hanging fruit...spark plugs, wires, cap/rotor, etc (air filter is new) but just wanted to throw this out in case there is some Pathfinder specific issue that you guys know about If that does not make any difference I will probably try a fuel filter then it will be time to check the electrical timing (any write-ups on this) and mechanical timing (what a PITA that will be)>

Thanks for any ideas :-)

[pathfinder9035]

MAF sensor. On some cars if maf is faulty it wont let u rev past 2-3k. remove the maf and see if the vehicle runs better (on most vehicles this works). if it does then the maf is your problem. But yeah definitely do all the other stuff also..plugs, wires even distributor should be replaced.

[KLL]

i agree with 9035. when you disconnect MAF sensor it acts same way as you described. when idling it is ok but when you want to rev it,it refuses.

Also when your engine is cold and no issues and if it is warm and it shakes, it stalls, it consumes so much, smells bad, it can be related to oxygen sensor(s). (you have 4 - 2 on each bank)

[woodc]

Speaking of MAFs: I have a 97 Pathfinder (bought it with a locked up engine....I am collecting dead Pathfinders apparently) but the MAF looks different (the thingy inside that the air passes over is a different shape) and has different part numbers. Should these be interchangeable...the connector is the same?

Thanks again

[woodc]

I checked at Autozone and the MAF has different part numbers for 97 and 98....

Suck!

[KLL]

its hard to answer. but engine is same. it should do the trick. do you have a photo of yours?

[woodc]

No photos yet...but I confirmed with 3 sources now that they have different part numbers so....yay Nissan <sigh> The good news is the 96-97 ones are more expensive than the 98-99 ones :-)

[woodc]

OK...over $100 later one known good replacement MAF installed....no change <sigh> I also changed 5 of the spark plugs (the back driver side one made me its b****).

Any other ideas?

When stone cold it starts and revs great up till about 3K RPM then it bogs. Once it warms up it will eventually die then not run at all till it cools back off (even after a couple of hours it did not want to run when I tried to move it out of the way this evening)

I will try swapping the front O2 sensors next I suppose....since I have a spare pair readily available and the part number is the same between 97 and 98...

[woodc]

I figured out today I cannot get the O2 sensors out of the headers sitting in the garge without an O2 sensor socket....much less the ones installed in the Pathfinder <chuckle> I was going to try swapping the coolant temp sensor the ECU uses from the 97 to the 98 just for grins...but the spot where it is on the 97 (right next to the coolant gauge sensor) is blanked off on the 98. Damn the changed a bunch of stuff between 97 and 98 <sigh>

[woodc]

After swapping out a ton of stuff (TPS, MAF, O2 sensors, wires, etc) the issue ended up being the distributor. I put another one on there and she revs just fine and continues to work even after she is warmed up.

Now it is time to adjust the TPS and timing <snicker>

Thanks all