I find the air filter can be sneaky on 4.0's with high mileage because
the engine sometimes will spit an oil film onto it. Even my CJ's just
messed up catching me by surprise. I went camping a couple weeks back
and used a full tank of gas for 210 miles! 70 freaking liters! I
haven't driven the CJ much in the last year so have very little miles on
that filter, but it was blocked with dust anyway.

It would be worth checking the wires too. They can back off a plug or
work out of the distributor cap sometimes.

Have you changed fuel brands recently? I do find a difference in
performance and mileage between brands.

Mike

Herb wrote:
>
> thank you everyone for the input. I don't believe it's my imagination. I
> drive it everyday, I know in dry day, it gets more power.
>
> Mike, I bought the plugs, cap, roter, and wires from the dealership. the air
> filter was changed 10,000km before.
>
> Is it possible the wires cracked(which I did not check) not insulated, or
> the end of the wires not fully pushed into the plugs.
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:42288892.93CC4A86@sympatico.ca...
> > How is the air filter? When they get older humidity can affect the air
> > flow through the dust.
> >
> > I don't know what plugs you used, but I have seen a pile of those
> > expensive bosch platinum plugs burn out fast in the 4.0 and 4.2
> > engines. They last for 6 month or a year, then the engine power up and
> > dies. The best is a Champion in my opinion.
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> >
> > Herb wrote:
> >>
> >> I have a 92 cherokee, 4L auto, 320,000km. I can feel it has more horse
> >> power
> >> in sunny days. In wet days it's lack of power.
> >> I changed plugs, ignitions wires, cap and roters 30,000km before.
> >> Anything I need to look into?
> >>
> >> thank you in advance.
> >>
> >> Herb

 

I find the air filter can be sneaky on 4.0's with high mileage because
the engine sometimes will spit an oil film onto it. Even my CJ's just
messed up catching me by surprise. I went camping a couple weeks back
and used a full tank of gas for 210 miles! 70 freaking liters! I
haven't driven the CJ much in the last year so have very little miles on
that filter, but it was blocked with dust anyway.

It would be worth checking the wires too. They can back off a plug or
work out of the distributor cap sometimes.

Have you changed fuel brands recently? I do find a difference in
performance and mileage between brands.

Mike

Herb wrote:
>
> thank you everyone for the input. I don't believe it's my imagination. I
> drive it everyday, I know in dry day, it gets more power.
>
> Mike, I bought the plugs, cap, roter, and wires from the dealership. the air
> filter was changed 10,000km before.
>
> Is it possible the wires cracked(which I did not check) not insulated, or
> the end of the wires not fully pushed into the plugs.
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:42288892.93CC4A86@sympatico.ca...
> > How is the air filter? When they get older humidity can affect the air
> > flow through the dust.
> >
> > I don't know what plugs you used, but I have seen a pile of those
> > expensive bosch platinum plugs burn out fast in the 4.0 and 4.2
> > engines. They last for 6 month or a year, then the engine power up and
> > dies. The best is a Champion in my opinion.
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> >
> > Herb wrote:
> >>
> >> I have a 92 cherokee, 4L auto, 320,000km. I can feel it has more horse
> >> power
> >> in sunny days. In wet days it's lack of power.
> >> I changed plugs, ignitions wires, cap and roters 30,000km before.
> >> Anything I need to look into?
> >>
> >> thank you in advance.
> >>
> >> Herb