I was getting 15-16 mpg in my 2001 Cruiser. Had new spark plugs installed about 1000 miles ago. Air filter is clean. All of a sudden I'm getting 12-13 mpg! Any suggestions on what to replace/change/look at? The vehicle has 39,000 miles on it.
With my 01 Limited automatic I get about 18 mpg on average, 24 at best on long trips.
Did you install dual plat Champion plugs and new wires? If not you likely need at least new ignition wires at this point. MOPAR has a performance set I use and recommend.
It is possible your O2 sensor is bad. This can be best checked out at a dealer who will hook it up to their computer. The only other thing I can think of is a restricted exhaust system. Let us know what you find. Also, if you go to a dealer, make sure your PT's computer has the most recent flash of the computer code updates.
Don't know if it's relevant or not, but I had a GM 3.8 whose mileage suddenly dropped by about 30 percent, while continuing to operate normally, and with no check light.
Turned out to be the coolant temperature sensor had failed.
Guess that caused it to always think the engine was ice cold, and operate with the electronic equivalent of the choke on full.
WHAT kind of spark plugs did you install??? ONLY use the factorry recomended part. IF you installed splitfire/platium/tripple spark garbage that could be your trouble !!!!!!!!!!!!!!!!!!
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