P0300 random multiple misfire

Vcook

Vcook

TJ Enthusiast
Joined
May 21, 2018
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Location
Chicagoland
My jeep is throwing this code again. It stumbled last night driving home and then the CEL came on, the only code is P0300 currently.

'06, 125k miles, 4.0, manual

Last week I changed the plugs and the cam sensor to address getting this code(as well as P0344 and P0335). After that it ran like a top for a couple hundred miles but now P0300 is back. Thoughts on what it might be? Coil rail?
 
Hard to say but the crankshaft position sensor can definitely cause that problem. That's what provides the engine's master timing signal. Also, exactly what brand and model spark plugs are you using? Single-tipped platinum plugs like the Autolite AP985 and Champion 3034 can cause that exact symptom too due to the waste-spark ignition design used in newer (distributorless) 4.0L ignition systems.
 
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What brand of replacement sensor did you use?

Also, what spark plugs are you using?
 
I would install a new computer.



Kidding. This seems a perfect time for a diagnostic tool, not a scanner.
But you have already wasted money 'throwing parts' at the problem.
 
Jerry Bransford said:
Hard to say but the crankshaft position sensor can definitely cause that problem. That's what provides the engine's master timing signal. Also, exactly what brand and model spark plugs are you using? Single-tipped platinum plugs like the Autolite AP985 and Champion 3034 can cause that exact symptom too due to the waste-spark ignition design used in newer (distributorless) 4.0L ignition systems.
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Autolite XP985

Chris said:
What brand of replacement sensor did you use?
Click to expand...
OEM Mopar sensor.

Any idea on the what the part number is for the crankshaft sensor?

While it's true I've wasted some money throwing parts at the problem the spark plugs that were in there looked pretty ratty, E3 plugs with a fair amount of carbon so I wouldn't say it was a mistake swapping them. The OEM mopar cam sensor was 32 bucks.
 
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Vcook said:
My jeep is throwing this code again. It stumbled last night driving home and then the CEL came on, the only code is P0300 currently.

'06, 125k miles, 4.0, manual

Last week I changed the plugs and the cam sensor to address getting this code(as well as P0344 and P0335). After that it ran like a top for a couple hundred miles but now P0300 is back. Thoughts on what it might be? Coil rail?
Click to expand...
Mines been throwing P0300 (2nd and 3rd) ever since i got it and it stopped for good once i got the Throttle Position Sensor fixed. TPS was running high... haven’t had the CIL on ever sense that was taken care of.
 
Last edited:
Jerry Bransford said:
Hard to say but the crankshaft position sensor can definitely cause that problem. That's what provides the engine's master timing signal. Also, exactly what brand and model spark plugs are you using? Single-tipped platinum plugs like the Autolite AP985 and Champion 3034 can cause that exact symptom too due to the waste-spark ignition design used in newer (distributorless) 4.0L ignition systems.
Click to expand...
Jerry what type of spark plugs would you then recommend? I limped home yesterday and got an error code P0300. I will change the plugs since I bought this jeep last summer. Funny thing is the jeep drove "normal" this afternoon no performance issues. Look forward to your response. Thanks!!
 
I replaced the coil rail and plugs on mine a couple of weeks ago and the engine has ran like a champ ever since. NGK coil rail and Autolite XP985 plugs.
 
Well replaced the plugs and crankshaft coil and so far so good. Thank you all for the input now I’m looking for the thread on wiring a hardtop rear heater and rear wash since I just bought a hardtop. This will be for the winters here.
Thanks again
 
I have an 05, 4.0, M/T, sport.
Just got the P0300 multiple misfire code the other day. Jeep lost power and started sputtering. It started back up and ran fine. It started again after reaching 65 mph on highway, then every time I stepped on gas. Took it out for a ride yesterday and nothing, ran fine.
I talked to a mechanic and he mentioned that in 05 -06 they change the CPS(cam positioning sensor) shaft and had problems down the road with the bearings going bad.
Going to put a better scanner on it this weekend to check for timing and to see if sensor is working and go from there.
I have NGK plugs with about 20k miles on them
Any thoughts on if this is the best course of action?
 
So I ended up replacing the cam sensor yesterday, going to see if I have anymore problems or codes.
I also found out the oil pump drive assembly on the 05-06 should be replaced with an aftermarket since the OE bearings do not have a long life.
 
05pf13 said:
So I ended up replacing the cam sensor yesterday, going to see if I have anymore problems or codes.
I also found out the oil pump drive assembly on the 05-06 should be replaced with an aftermarket since the OE bearings do not have a long life.
Click to expand...

And???

I'm getting similar "P0300" after going through a big water puddle on a recent Jeep trip.
 
Coming to work this morning and suddenly the jeep has no power and getting P0300 random misfire codes
Any idea where to start?
 
voodooridr said:
Coming to work this morning and suddenly the jeep has no power and getting P0300 random misfire codes
Any idea where to start?
Click to expand...
My initial thought is a possible crankshaft position sensor issue. If you decide to replace it try to find a top-quality replacement if you can't find a Mopar. Avoid store brands and cheap online brands. NAPA is often a good source for better quality replacement parts if you go for their top premium choice.
 
Thanks, this thing is starting to wear on my last nerve, heater core yesterday now this today and was throwing a P0431 code all last week
And randomly the oil pressure gauge falls to zero when it drops down to idle after driving
 
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