Rough idle/cylinder one missfire
 

My 01 xj has developed a rough idle and code p301.. It didn't start acting up until we got home from our obx 4x4 trip.... I have replaced the spark plugs and coil rail... I have moved the injectors around to see if the miss fellows the injector and cylinder one is still dead... I have confirmed that I have spark and can hear the fuel injector firing threw a screwdriver.... When I unplug the fuel injector to cylinder one nothing happens... My check engine light is also blinking... I sea foamed the engine the other night and the idle has gotten worse.... Can you guys help me out.... I think from my readings I have a bad or burnt exhaust valve... Any input would be great.. Going to do a compression test this weekend..... Thanks for the help

If you have fuel and spark, compression would be a good next check.
What did the plug you removed look like? Wet with gas?

The plug was soaked in gas!! You can smell gas the minute you pull it out.... I did an ohm test on the injector and got 15.1... Idk if that's bad or good... New to the jeep world

Had similar problems with my cherokee. Spent a lot of money on sensors thinking thats where the problem was. Then, took it to a shop and it was throwing codes that the #4 injector was malfunctioning but to me it seemed to be working fine, So I tried resetting my ECU. Check Engine Light Went Away and havent had any problems since. I would try that first before you start spending money.

https://www.cherokeeforum.com/f2/jee...ocedure-46047/

Correction on injector ohms.. It red 13.8 on all injectors... I know the injector is working because the spark plug is soaked in oil....brand new plug is soaked in gas already also

I finally got around to doing a compression test.... I only have 55psi on cylinder one... I added about a shots worth of oil and tested again and it went up maybe 8-12 psi... Does this sound like a valve issue.... 8-12 doesn't seem significant enough to be a ring issue.... Thanks for the help

Adding oil and doing a wet compression test and the psi only going up 8-12 psi would confirm a valve issue correct

Yep, that's the usual suspect.

I believe I have found the issue... Spent a few hours the last couple of days pulling the head off.. Cylinder walls look good but the head... I went and got some diesel and proud it in the combustion chambers... Diesel leaks pretty good out of cylinder one intake port.... Soo got rebuilt head today and will finish putting it back together tmrw.... Diesel leaking def means bad intake valve seal correct

Bad/dirty, valve seat, not seal. Yes.

dosnt any body do cylinder leak down testing anymore

No. Too hard to find the proper tooling or too lazy to make their own.