BMWGuy
NAXJA Forum User
- Location
- Columbus, OH
Searched and found discussions on cracked exhaust manifolds. 2001 Cherokee Sport, 4.0 with auto trans and 150,000 miles. Fuel mileage sucks (around 12mpg combined). Runs great, no codes, operating coolant temp fine. Poured Seafoam in TB to generate smoke to detect manifold leak. Didn't see any smoke in the engine compartment. Changed pre-cat O2 sensors and that didn't seem to change anything. At a loss for why fuel mileage down (plugs changed at 100k miles, idles fine). If air is sucked into the exhaust manifold to alter O2 readings would that mean I wouldn't see the smoke from the Seafoam?
Sorry for the long post but this is really bugging me. Been going on for several months.
Sorry for the long post but this is really bugging me. Been going on for several months.