jk rough idle and EML with codes

[BillyK83]

Hey folks,

Not sure if this is the correct forum for this but here goes.

My 2008/09 3.8 man jk wrangler recently started idling rough and throwing error codes. The codes are p0300 and p2305. I have tested the leads and the alternator already and they are fine. It has livewires, screamin demon coil pack, champion platinum plugs all 6 months old. I am reluctant to take it to dealer as in WA they charge like wohnded bull's and I would like to do what I can first to diagnose the problem. I am hoping it's not the PCM. The faulta are for multiple random misfires and 2nd coil insufficient ionisation I believe. The EML light flashes and alarm chimes.

Any guidance, ideas, options would be greatly appreciated.

Cheers,

Will

[humdingerslammer]

Same problem not 2 weeks ago. I had Champion platinum plugs (25000 km) and Live wire plug leads (25000 km). They should have been good for at least 65000km. My original OE leads did 120000 km and the original plugs about 60000km without a problem. So I took them all off/out. The plugs seemed OK but the gap was possibly a little bit wider than should have been.I think this is a problem with the platinum plugs, from what I can gather from Jeep forums in USA. Some soot here and there on the plugs. Replaced with stock standard NGK plugs from Repco. I replaced the wires with Omix-Ada OE ones.I always have a spare set on hand. JKU now like new.

[BillyK83]

Originally Posted by humdingerslammer

Same problem not 2 weeks ago. I had Champion platinum plugs (25000 km) and Live wire plug leads (25000 km). They should have been good for at least 65000km. My original OE leads did 120000 km and the original plugs about 60000km without a problem. So I took them all off/out. The plugs seemed OK but the gap was possibly a little bit wider than should have been.I think this is a problem with the platinum plugs, from what I can gather from Jeep forums in USA. Some soot here and there on the plugs. Replaced with stock standard NGK plugs from Repco. I replaced the wires with Omix-Ada OE ones.I always have a spare set on hand. JKU now like new.

Thanks, I pulled out the plugs today, closed the gap a smidge and gave them a clean put them back in and same problem. 2 and 6 were grubby but the rest looked ok besides the electrodes looking a little flat. Will replace the plugs and test then replace the leads also if need be.
Failing that it will be off to the shop.

Dissapointing when you fork out cash for what is supposed to be a premium product.

Cheers for the advise.

[Redbox]

have a 2008 JKUR, i have had this fault before, my PCM failed earthing #2 coil all the time the ignition was on, opened up PCM found #2 transistor of the ingnition blown of the bourd, had screming deamon, uridium plugs, mix of bosch & live wires ( as had cooked 2 live wires), problem poped up again had gone to OEM leads, uridium plugs & screamin deamon, have swaped ot to Cooper plugs prob gone, the center electrod was melting on 4 of the 6 plugs, i am dosing with injector cleaner, will get an injector flush done as well.

i love my JEEP but some times it shits me!

auy one else have any sergetions?

[MightyMouse]

Revert to stock and see what happens ?

[BillyK83]

Got some cheap ngk's for troubleshooting, fitted and still no difference, VERY rough idle and EML still up and flashing/alarm, vehicle is undrivable in it's current state Error codes p300 and p2305.

Looking for some leads locally to fit and test also and a stock coil from the wreckers possibly as my old one went out in the recent move.

Failing that, anyone know what a new PCM will set me back or if I can just get one from the wreckers? I think I heard that they have to be programmed for the vin#

Also anyone know a good Jeep mechanic in the Perth area?

Worst time of year to be trying to get parts in...

[BillyK83]

Originally Posted by Redbox

have a 2008 JKUR, i have had this fault before, my PCM failed earthing #2 coil all the time the ignition was on, opened up PCM found #2 transistor of the ingnition blown of the bourd, had screming deamon, uridium plugs, mix of bosch & live wires ( as had cooked 2 live wires), problem poped up again had gone to OEM leads, uridium plugs & screamin deamon, have swaped ot to Cooper plugs prob gone, the center electrod was melting on 4 of the 6 plugs, i am dosing with injector cleaner, will get an injector flush done as well.

i love my JEEP but some times it shits me!

auy one else have any sergetions?

Hey Redbox

Did you get your pcm repaired or replaced?

I have reverted to stock everything and still have the same problem. I was sure I had it sussed when I tested the screamin demon coil and 2 - 5 had no resistance telling me that it's shot, replaced with stock coil but same problem. I imagine that a fault in the pcm similar to yours could have caused the coil to fail.

Any info on what you did would be greatly appreciated as I am in perth also and planning where to take it as I am out of my capabilities beyond this.

Cheers,

Will.