P0300 and C121C Problem - '06 XK 3.7L

[FLYCAV]

How's your oil level?

Oil level is good.

......... because you have a better chance of getting struck by lighting while you're on your way to collect your mega millions lottery winning than you are to have multiple injectors go bad at the same time to cause P0300.

I just wish the odds of winning the Mega Millions jackpot were more like the odds of my Jeep throwing a P0300 code on the way to pick up a 12 pack.

Normally ECU issues that result in P0300 result in an new ECU, not just programming.

I was afraid of that.

Fuel supply issues could be anything from pressure bleed-off to the pump going bad. Doubtful that its an injector issue because you have a better chance of getting struck by lighting while you're on your way to collect your mega millions lottery winning than you are to have multiple injectors go bad at the same time to cause P0300.

I just might have to invest in that service manual afterall.

[Matt]

Use this
https://dl.dropboxusercontent.com/u/...2005-WK-SM.pdf

[thance]

Use this
https://dl.dropboxusercontent.com/u/...2005-WK-SM.pdf

Do you know of a similar link for a 2010xk?

[Matt]

No, but they're practically identical except for the body and accessories.

[FLYCAV]

Thanks for the link Matt. Thats' awesome.

Replaced the PVC valve this morning and reinstalled factory tune. Still throwing the P0300 code. I guess I'm just about out of cheap solutions.

...and to kick me while I'm down, last night while online researching the issue more I got the dreaded "FBI Cybercrime/MoneyPack" virus and locked me out of my computer. was up most of the night and spent half of today getting that off my computer. (fingers are crossed)

[Matt]

Do you have a scanner that you can see which cylinders are misfiring?

I'd also check the PCM connection. Disconnect it, check the contacts, use some electrical cleaner, and reconnect.

With the engine running spray some carb cleaner around the throttle body, valve covers, etc to see if there's a vacuum leak. You'll know if there is one because the engine will rev up when it sucks in the carb cleaner.

[FLYCAV]

Do you have a scanner that you can see which cylinders are misfiring?

I'd also check the PCM connection. Disconnect it, check the contacts, use some electrical cleaner, and reconnect.

With the engine running spray some carb cleaner around the throttle body, valve covers, etc to see if there's a vacuum leak. You'll know if there is one because the engine will rev up when it sucks in the carb cleaner.

All I have is the Hypertech unit which will just show the DTC's and it has only thrown the general P0300 code no codes identifying a specific cylinder.

I did disconnect the PCM plugs and cleaned them out with electrical cleaner and made sure they were secure again.

I didn't check for a vaccum leak but I'll try that in the morning.

If it's the PCM and I end up replacing, would I need to have a program loaded at a dealer or would it come ready to plug and play? I was actually Googling the part number for the PCM last night. The first search result I clicked on was what cause me to get the computer virus...That would be a little ironic if the PCM was responsible for taking down my Jeep and my computer.lol.