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96 XJ Running Rough..thowing mulitple codes

Bobby@Bullydog

NAXJA Forum User
Location
Texas
Ok so Ive searched everywhere and done everything known to man BUT solve my problem with this.

Basically I bought it Jeep and it was running rough...would blow some black smoke when heavy in the throttle.

Threw a p0171 - System Too Lean
Replaced the first o2 sensor and that code went away

Then a week later the light comes back on and it starts running rough again..no smoke now but it trys to idle very low around 400-500 rpm and sputters at idle like a tractor. runs fine off idle and through the rest of the RPM range though.

I get these codes now

p0300
p0301
p0303


I was able to swap injectors this weekend. Just swapped one and two beings it was throwing a code for misfire on 1 and 3. Didnt change a thing so it still comes up Misfire on 1 and 3. So that rules out the injectors, plugs, wires, cap, rotor, pick up coil. Not sure what else to check other than swap out with another ECM.

Got another code on start up this morning P0141 Oxy Sens Heater Circ (bank1, Sens2)


Any ideas guys?
 
Yea all the wiring is good there. Ive pretty ran over everything I could think of and now im just stumped and had to resort to getting help. Hurts my pride not being able to fix it myself.
 
I believe there is a fuse for the O2 sensor heater in the PDC? Sens 2 would be the downstream sensor I think. I missed how you eliminated plugs, wires, cap and rotor? Throttle body and idle air controller nice and clean?
 
Eliminated them by replacing it all!!

IAC is clean and working properly and so is the TB.
I actually ran some Sea Foam through that and cleaned all the carbon out of the motor.
 
isnt there a fuse for the o2 heater curcuit?

yes It is powered thru the ASD relay.Fuse # 20 -30A
If that fuse was blown -you wouldn,t be having a miss-fire-- It would be a No Start condition.

Have you replaced the distributor ? A worn shaft/bushings will cause a miss fire.Keep it up long enough and the cat will be gone too.

Wayne
 
No i didnt replace the Distributor...wouldnt make sense to only misfire on 1 and 3 though.

and the cat has already been removed...dummy pipe in place with an o2 sensor in it.
 
Any more ideas?

I dont think compression matters....2 cylinders just arent firing half the time.

Whats weird is it runs fine when off of idle but at idle it just sputters like crazy

I still get 16-18mpg on the highway
 
It has all new Cap and rotor, plugs and wires and the problem is still there and did not change a bit. Replaced pick up coil and it still did not change.
 
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