error code P0301

Would a new plug in cylinder 1 fix this? The guy at the parts store thought it might.

If it will can anyone tell me how can i tell where cylinder 1 is? I don't want to change the wrong plug after all :) The jeep i have has a spark coil rail.

the exact error says

P0301
Cylinder 1
Misfire detected

Could be several things.... hopefully it's minor (ignition related)

Try finding a factory service manual for your car, it will list the cylinders in order. I would then try replacing the spark plugs (put an entire new set in the car) and wires. If that doesn't do the trick, try replacing the cap and rotor.

Could be several things.... hopefully it's minor (ignition related)

Try finding a factory service manual for your car, it will list the cylinders in order. I would then try replacing the spark plugs (put an entire new set in the car) and wires. If that doesn't do the trick, try replacing the cap and rotor.

Thanks for the info. It only did this once for my wife like always she said the engine light was blinking at the time so she brought the car back home later in the day when i got home it ran fine.......it was still just as cold i don't get home untill night.

It has been really cold here i wonder if that makes the bugs come out today for a overnight low its -4 F yestefad when she ran the car it was around 20F

i had a cylinder that would fire sometimes and sometimes not. it was the fuel injector. not sayin thats it cause i'm no mechanic but i thought i'd share incase you hadnt considered it.

error code P0301

Would a new plug in cylinder 1 fix this? The guy at the parts store thought it might.

If it will can anyone tell me how can i tell where cylinder 1 is? I don't want to change the wrong plug after all :) The jeep i have has a spark coil rail.

the exact error says

P0301
Cylinder 1
Misfire detected

Cylinder #1 on the 4.0L I-6 is the front cylinder in the front of the vehicle. I would replace all of the spark plugs if you're going to go ahead and pull the coil rail off. The 2001 4.0L I-6 doesn't have spark plug wires. It has the coil on plug design.

"""error code P0301

Would a new plug in cylinder 1 fix this? The guy at the parts store thought it might.

If it will can anyone tell me how can i tell where cylinder 1 is? I don't want to change the wrong plug after all The jeep i have has a spark coil rail.

the exact error says

P0301
Cylinder 1
Misfire detected""""



I got a 2001 Cherokee and Have had A Bad missfire in Cyl 6 and I did Replace the plugs and NO Avail. Next thing I did I replaced the one injector on Cyl. 6 And BINGO Runs SO much better now and lookin at the old one it WAS pretty Plugged up at least it looked like it was cause there was so much crap on the tip of the injector!!!

I have a 1999 Grand Cherokee Laredo v6 4wd with P0301 code too. It tries to start with a super rough idle type sound and sometimes fails to start. When this rough start happens, sometimes you have to try a couple of times to restart until you get a 'clean' sounding engine to drive away. Twice the engine has stalled when idling while dropping someone off at the curb.

Replaced spark plugs, did fuel system cleanout at Firestone. Didn't fix. They say there's a bulletin in the Mitchell book about issues with this year/model and valves -- advising me that I might have to get dealer to replace valve. Dealer says it could be as much as $8k once they open up engine and find what's wrong.

Don't know if related, but started at same time, if you just idle in the parking lot, after several minutes the engine will overheat sometimes and shut down.

Can someone advise literally what I should ask for as next steps when bringing to dealer or local automotive shop? Or is this car really dead and I should look for a new one?

Any guestimates also on how much this issue might cost if I have to "replace the valve" or other scenarios?

Thanks.





"""error code P0301

Would a new plug in cylinder 1 fix this? The guy at the parts store thought it might.

If it will can anyone tell me how can i tell where cylinder 1 is? I don't want to change the wrong plug after all The jeep i have has a spark coil rail.

the exact error says

P0301
Cylinder 1
Misfire detected""""



I got a 2001 Cherokee and Have had A Bad missfire in Cyl 6 and I did Replace the plugs and NO Avail. Next thing I did I replaced the one injector on Cyl. 6 And BINGO Runs SO much better now and lookin at the old one it WAS pretty Plugged up at least it looked like it was cause there was so much crap on the tip of the injector!!!

99 didnt have the v-6/ it had the straight six, and there's nothing wrong with the valves as far as i'm aware of.
check your fuel injector.

On a straight 6 the #1 cylinder is always the front one. It depends on the make and model of other cars, but generally if it is a V8 or V6, the number one plug is the one on the passenger side front. If you take the coil rail off, you might as well inspect and at least clean all the plugs, but I would reccomend replacing them. I have had been driving nothing but Jeep Cherokees since 1988 and I can tell you they are touchy about what plugs you use. Make sure you get the right heat range and get a decent plug. Mine would barely run on Autolites or Champion. I had the best luck with the low end Bosch platimum plugs, but make sure they are the right heat range. Also clean off the rubber plug boots and then use the dielectric grease so no moisture gets in. Each coil in the coil pack fires two cylinders so if you are only missing on one, it is not the coil pack. If that doesn't do it, the other thing that might cause it to misfire could be a dirty or damaged injector. I would reccomend replacement. My experience with these so-called refurbished injectors is that all they do is clean them and send them back regardless of what they tell you. If they were clogged or leaked before you send them in, they still leak or are clogged when you get them back. So just get a new one. It takes maybe 15 minutes to change them out. Just be careful not to damage the O-Rings or get new ones. You will also want to get any dirt, dust or dabry off the manafold before starting to remove the injector rail. You don't want any dirt getting in the intake. Make sure to lubricate the O-Rings before re-installing the rail.