I just replaced my engine in a 1988 Cherokee with a 2004 model from a Wrangler. It is a 6 cylinder and only gets about 11mpg. The engine seems to run good but is drinking gas. Any one have any suggestions?
If I replace all the sensors, should I buy sensors for the 2004 model engine or the 1988? I paid to have the engine swapped and I am not sure if the sensors were changed or not. If the electrical plugs are the same, most likely they did not replace the sensors from one engine to the other. I would bet money that I have 2004 sensors going to a 1988 control unit.
IIRC the 88's only had one O2 up near the exhaust manifold/header, as they were OBDI's. I want to say that the OBDII's were '96 and up, and they run two O2 sensors, one in the same as the OBDI's and another down after the cat (or near it). Don't know if that'll cause the mass fuel consumption, but it's worth looking into.
Other'n that, try Seafoam through the intake, followed by a routine plugs/wires/dizzy rotor and check the points in the cap to be sure they're in good condition.
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