01 jgc loss of power and gas mileage

[racer77]

my 01 grand cherokee 4.0 120k last year was getting 17mpg.
now only 13.9 and within the last few months it has been real slow. you cant pull of quick into traffic. it just slowly gets up to speed.
also seems like when your already moving, and you want to pick up speed. it just goes up slowly. it dosnt make the loud rev and take off.
i have put in new good plugs. air filter, and injector cleaning service. with no luck.
can someone please help me out?
thanks, jim

[racer77]

Good lookin out people!!
Big help.
This place is useless.
Im off to find a good forum.



C-ya

[fredjacksonsan]

Hey, sorry the traffic isn't what you expected it to be. Some of us can't be on here all the time.

If you rev the engine in neutral, does it stumble above about 2000 rpm? This could indicate a blocked catalytic converter; there was a recall on the 98-99's for that, they might have used one of the bad cats on yours.

Is there a black/wet residue on the inside of the tailpipe? If so, then your O2 sensor could have failed. They fail in the rich position, which leaves a lot of unburned gas in the exhaust, kills your mpg, and can make it sluggish.

Have you put larger tires on it?