88 runnin super rich/8 mpg

[ktmrider]

88 mj i6 5-speed 185,000 miles

 

Well lately my mj has been running super rich, before i noticed the low mpg i noticed a banging in the muffler like the excess gas is combusting in the cat. I know you guys are gonna tell check sensors, plugs and stuff. But here's where it has me baffled it's doing it cold or hot engine(closed loop and open loop) so sensors aren't even coming into play when cold. I thinks it's the injectors or fuel pressure regulator. Any ideals?

[Eagle]

Oxygen sensor.

[mnkyboy]

X2 I would start with the o2 sensor

[ktmrider]

sorry i forgot to add i jest replaced the o2 sensor and vac lines a few days ago and it made no difference.

[mnkyboy]

Have you checked the plugs for fouling,it would help if you could isolate which cyls are over fueling.

[Pete M]

x2 could be one of the injectors is stuck open or leaking.

[ktmrider]

Have you checked the plugs for fouling,it would help if you could isolate which cyls are over fueling.

 

thats a good ideal i'll check tomorrow or saturday.

[cz777]

x2 could be one of the injectors is stuck open or leaking.

please add in vacaum leaks in map sensor hose and bad grounds ...

[Eagle]

Also check the wires from the O2 sensor. If the signal from the O2 sensor isn't getting to the ECU, the ECU will probably be operating full-time in either open circuit mode or "limp home" mode.

[ktmrider]

ok so i went ahead and did a tune up plugs,wires,cap, and rotor and here are the plug most where sooty but not wet. number 2 and 3 looked the best

 

under the cap it was rusty, never seen that before

 

and here's where the M.A.P. vacuum line plugs in there's a open hole on top. Should there be a vacuum line in there and if so where does it go?

[ktmrider]

anyone??

[tugalo]

the Map sensor is the only thing plugged into the throttle body on that side on my 88.

I believe the Map sensor line goes into the bottom hole and I think the upper one is a dummy.

[dakal]

x2