2000 TJ - I6 4L, 5 Speed Manual - 163K mi
P0300 P0302 P0306 - Multiple Misfire
This is our plow jeep and we occasionally use it to run around town.
I changed the head to a TUPY head in November 2022 due to loss of compression which was attributed to leaking valves.
New parts used: Remanufactured Head, Head Gasket, Head Bolts, Hydraulic lifters, pushrods, rockers, spark plugs (Champion 3412), coil pack, crank position sensor
The new, reman head, did the trick and instantly we got a major power boost from the engine that was never there before. In the process I discovered that the Crank Position Sensor wire was nearly severed so I replaced it with a MOPAR sensor. All was well with it and plowed our driveway etc no worries.
July 2023, all of the sudden it has developed a severe misfire in multiple cylinders with near complete loss of power.
I can smell gas when it is running, plugs have a new black soot on all 6 of them. It sounds to me like there is a timing issue... or maybe a short... or a sensor has failed
OBDII Codes - P0300 P0302 P0306 - Multiple Misfire
OBDII Powertrain Live Data at idle:
PCM PID
Fuel Sys 1- CL
Fuel Sys 2 - N/A
Calc Load - 9.8%
ECT - 142F
STFT B1 (-5.5%)
LTFT B1 (-33.6%)
MAP - 14 inHg
Engine RPM - 790
Vehicle Speed - 0 mph
Spark Advance - 9.5
IAT - 183F
TPS 18.4%
O2SLoc - O2S11/2S12
O2S B1 S1 - 0.840V
STFT B1 S1 - (-5.5%)
O2S B1 S2 - 1.100V
STFT B1 S2 - 99.2%
The Code Reader (Innova 3100RS) shows that it successfully monitored the following:
What I've physically checked thus far:
I can run a compression and leak down test if need be, I am good with a DMM and I have access to a power probe IV.
I'd like to diagnose the problem, not throw parts at it.
Appreciate everyone's help!!!!
P0300 P0302 P0306 - Multiple Misfire
This is our plow jeep and we occasionally use it to run around town.
I changed the head to a TUPY head in November 2022 due to loss of compression which was attributed to leaking valves.
New parts used: Remanufactured Head, Head Gasket, Head Bolts, Hydraulic lifters, pushrods, rockers, spark plugs (Champion 3412), coil pack, crank position sensor
The new, reman head, did the trick and instantly we got a major power boost from the engine that was never there before. In the process I discovered that the Crank Position Sensor wire was nearly severed so I replaced it with a MOPAR sensor. All was well with it and plowed our driveway etc no worries.
July 2023, all of the sudden it has developed a severe misfire in multiple cylinders with near complete loss of power.
I can smell gas when it is running, plugs have a new black soot on all 6 of them. It sounds to me like there is a timing issue... or maybe a short... or a sensor has failed
OBDII Codes - P0300 P0302 P0306 - Multiple Misfire
OBDII Powertrain Live Data at idle:
PCM PID
Fuel Sys 1- CL
Fuel Sys 2 - N/A
Calc Load - 9.8%
ECT - 142F
STFT B1 (-5.5%)
LTFT B1 (-33.6%)
MAP - 14 inHg
Engine RPM - 790
Vehicle Speed - 0 mph
Spark Advance - 9.5
IAT - 183F
TPS 18.4%
O2SLoc - O2S11/2S12
O2S B1 S1 - 0.840V
STFT B1 S1 - (-5.5%)
O2S B1 S2 - 1.100V
STFT B1 S2 - 99.2%
The Code Reader (Innova 3100RS) shows that it successfully monitored the following:
- Misfire Monitor
- Fuel System Monitor
- Comprehensive Component Monitor
- Oxygen Sensor Monitor
- Oxygen sensor Heater Monitor
What I've physically checked thus far:
- Coil appears to make good spark on all 6 cyls by using a spark plug inserted in the coil boots and grounding it via jumper cable to the body ground.
- I tried a brand new coil to be certain and got the same results as with the existing (new in Nov 2022) coil.
- I don't see any issues with wiring
- Visual check of vacuum lines
I can run a compression and leak down test if need be, I am good with a DMM and I have access to a power probe IV.
I'd like to diagnose the problem, not throw parts at it.
Appreciate everyone's help!!!!