NOT FIXED P0306 - 2002 Sahara 4.0 automatic (at wits end!)
- Thread starter Smokin151
- Start date
Ok...so we know it works fine without the O2 sensor...right...
So perhaps we need to know if the O2 was actually the cause...or if not having the O2 plugged in forced the computer to stay in closed loop?
Here's my theory... everything works fine in closed loop...but you get a misfire on 6 in open loop...
Thoughts?
-Mac
So perhaps we need to know if the O2 was actually the cause...or if not having the O2 plugged in forced the computer to stay in closed loop?
Here's my theory... everything works fine in closed loop...but you get a misfire on 6 in open loop...
Thoughts?
-Mac
I would check the mini cats. Here’s a melted mini cat that caused a single cylinder misfire code only after cruising on the highway for a period of time followed by limp mode.
Mac,
Unplugged bank 2/1 o2 sensor last thinking the same theory. DTC for that one popped so I test drive..same thing. CEL flashing only under hard load. I hook the noid back up...nothing. key off engine restart I have flashing again. I can't seem to figure out why I loose injector pulse then a quick KOEO and it's back. I came back home to check resistance, ohms out. No O/L. See attached photo. I have traced every freaking wire. I'm drawing a blank as to what is causing this.
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Right...so the wiring is good, the injector is good, the PCM is good, coil is good, you have compression and leakdown says you have good valves...right?
Need to do some research as to what specifically triggers a misfire code in the PCM. Let me do some searching.
-Mac
Need to do some research as to what specifically triggers a misfire code in the PCM. Let me do some searching.
-Mac
With the fact that if I restart and it goes away. I really thought the PCM was my problem. I figured injector driver was going out. Wranglerfix says no problem.
How much of the wiring harness did you strip down? I’m thinking you may have to go deep into it
I'm with @Chris on digging deeper into the harness. These jeeps are known for wiring issues in the harness behind the valve cover.
I would open it up and reinspect for chafed or broken wires. Also inspect the connectors for water intrusion/corrosion.
You said that you Ohm'd out the circuits, perhaps you need to do a voltage drop test.
You can have a wire with all but one strand ohm out perfect but if the circuit is loaded, it can create excessive resistance.
I would open it up and reinspect for chafed or broken wires. Also inspect the connectors for water intrusion/corrosion.
You said that you Ohm'd out the circuits, perhaps you need to do a voltage drop test.
You can have a wire with all but one strand ohm out perfect but if the circuit is loaded, it can create excessive resistance.
I figured I would get it to hard fault and upload the freeze frane data. Maybe it triggers something.
Mostly wondering what's going on with the CPS.
Some good data there...but no smoking gun and I'm sure there are more data points.
-Mac
Some good data there...but no smoking gun and I'm sure there are more data points.
-Mac
I used a Napa Echlin crank position sensor on my 97 AMD that got rid of my misfires.
Definitely need to look at both. PCM data will help or throw parts at it.
New parts are all shit these days. Made in China no quality control junk.
-Mac
Definitely need to look at both. PCM data will help or throw parts at it.
New parts are all shit these days. Made in China no quality control junk.
-Mac
I will get a different scanner tomorrow, it's a lot more detailed then my readers. I will update then. Thanks for your time on this. And I'm so tired of throwing parts at this thing. I can drive 100's of miles with no CEL. The minute I WOT I get this. Seems to run way better cold, once warmed up is when it seems to f'up. I did replace the coolant temp sensor with an oreily I believe. Seems to be reading fine. WE will figure this out I'm sure.
Yeah I'm finally trusting my TJ after three years of fixing things. Replacing bad lift components to fix steering issues. Chasing misfires. Four oil pressure sensors. Evap codes. Then my wife hit it on the freeway and folded the frame...so tub and frame swap. Clutch. Transmission. Water pump. Timing chain.
You'll get there. Just need a little more time and patience.
-Mac
You'll get there. Just need a little more time and patience.
-Mac
I'm thinking I need a junk yard run and try to find a 4.0 and steal the crank sensor if it's stock