1997 Jeep Wrangler check engine light

DFORT233

MEMBER
1997 JEEP WRANGLER
4 CYL
4WD
MANUAL
120,000 MILES

I have a check engine light on, code read the bank 1 running lean, but it was not running lean, I had black smoke come out of tail pipe. The mechanic has taken out the thermostat and the check engine light goes out and runs well. Its fooling the system the engine is not running at its normal operating temp, therefore calling for too much fuel! I also replaced the o2 sensors up and downstreem the cat and new fuel pump and fuel sending mech.I dont know where to turn ! Help me ! Thank you

2 Replies

CJ MEDEVAC

MECHANIC
11,004 POSTS

See my profile, I do not know your rig.

Just throwing stuff at you,

The computer compensates for some sensors not being on-line (yet, such as a "warming up" O2 sensor) Using Preset values (inefficient) to make engine run, until REAL WORLD values, are sent to the computer via each sensor

Now, with thermostat removed, engine coolant temperature sensor is "OFF- LINE" computer is now Compensating for it, with preset (inefficient) values

Too many factors going on at the same time, to have/read an accurate Equation?

Would you not put all back original, for accurate coding, to insure your O2(s) was the problem and is now, "POSSIBLY FIXED"?

Maybe your injector(s) are bad/ need cleaning etc.

Wadda you think?

Love, Turddog

EVEN "WILLY" LOOKS PUZZLED