Novak Conversions Jeep Wrangler TJ radiator

Intermittent misfire and rough idle (2005 Wrangler X 4.0 Automatic)

Did some more diagnostics over the weekend. I rented a fuel pressure test kit and some NOID lights from O'Reilly's

The fuel pressure was right on 60psi for all throttle ranges and at idle. After turning off the engine the pressure dropped to 55-56psi within a few seconds but stayed at that level for 35 minutes.

I physically inspected and did continuity checking on all the main ground wires, loosened and tightened them. I checked the resistance of each injector, and I checked the continuity (or lack thereof) between the two leads to injector #1 between ground and each other. Gave everything a good wiggle and physical inspection all around the loom and back around the rear of the valve cover. Everything looked great, all readings were as expected on the multimeter, so I did the NOID light test and everything looked good there, too.

So I pulled the coil rail and plug #1. To my surprise, the plug looks pretty foul after only 6 months since new.
spark_plug.jpg


I bought a bore scope a while back so I put that thing to use, and I think I found my issue. Looks like a lot of oil is leaking into cylinder 1 around one of the valves.

valve_leak1.JPG
valve_leak2.JPG


The head of the cylinder itself is not in bad shape but it is covered in a thick crust of oil.
cylinder_head1.JPG
cylinder_head2.JPG

The good news (I think) is the cylinder wall doesn't look too bad. I don't see scoring or other indicators of bad rings etc.
cylinder_wall1.JPG
cylinder_wall2.JPG


So, my Jeep gurus, what is my next step? I am thinking valve cover gasket and valve stem seals, thoughts?
What all should I do while I am in there? Should I run a leak down test and compression test now even though I have seen this issue with the bore scope?
 
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read this thread with immense interest, thanks for sharing as I am sometimes experiencing your identical P0301 issue, and from now on I'll be starting from your step 1 to try to seek where the issue is in my Jeep.

curious as well of suggested next steps.
 
read this thread with immense interest, thanks for sharing as I am sometimes experiencing your identical P0301 issue, and from now on I'll be starting from your step 1 to try to seek where the issue is in my Jeep.

curious as well of suggested next steps.

I’m about to finish this thread out and maybe start another one. I do have some lessons learned here you may benefit from.
 
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So I ordered parts to do valve stem seals and valve cover gasket, and while those were coming in I started driving around with the live data scanner sett on misfire monitor. It turns out cylinder 1 was misfiring most of the time, not just at idle, and cylinder 6 had a few misfires but was not throwing the P0306 code.

The parts came in, so I did the following:
-Remove negative battery terminal
-Unhooked air temp sensor and removed intake tube, stuffed a rag down in the throttle body to keep stuff out
-Unplugged and removed ignition coil
-Removed all 6 spark plugs and numbered them. Using a bore scope I saw that cylinder 6 also had oil leaking into it from around the intake valve just like #1
-Used masking take to number all the injector wiring and disconnected all injectors
-Pulled the fuel pump relay

At this point, I put the terminal back on the battery and ran a dry compression test on all cylinders. I wanted to decide at that point whether to take it in for a head gasket and just rebuild the whole head. Luckily, all 6 cylinders showed 120-130 lbs pressure on the first full compression stroke, resetting the gauge each time and doing each cylinder 3 times. I needed a buddy to turn the key in the cab while I operated the gauge.

-Once again unhooked negative terminal from battery
-I put the spark plugs barely into one thread of the cylinder to keep debris out but still not seal so I could easily turn the engine by hand.
-I pulled the heater core hose mount off the valve cover stud and held pulled those out of the way
-I undid the AC line mount from the front of the valve cover and removed the mount
-Labeled and unplugged the coolant temp sensor and AC pressure switch which allowed me to pull the wire loom up off the driver side of the valve cover and out of the way
-I removed the wire loom holder from the back of the valve cover

That thing is difficult.I would recommend toaking the top off it first while it is attached to the valve cover stud. Then remove the nut on the passenger side stud and pulling up while rotating it to the rear. At that point you can move the whole assembly behind the valve cover and get it out.

-Then carefully removed the CCV rigid tube from the rear, and the CCV air inlet from the front.
-Unhook the throttle and cruise control cable from the throttle body, then take the mount off the intake manifold, unclip the cabling from the top of the valve cover, and pull it all off to the side.

I did all of this to allow for the valve cover to be removed without unhooking the AC or heater core lines. Remove valve cover bolts
-Stand on the passenger side and rock the top of the valve cover away from you so that it comes out from the post at the driver side rear of the head.
-Once you are clear from that, lift ht valve cover up, then rotate it towards the passenger side so that the passenger side front lip of the cover can be freed from the AC and heater lines.

There are several good write ups on here about doing valve cover gasket, rocker arms, valve springs, etc which I used to disassembel the valvetrain and replace all the valve stem seals. I won't repeat all that, just remember:
-Inspect any parts you intend to re-use for wear. In my case, I re-used everything except the valve stem seal. Specifically check for wear between the rocker arms and the bridge/saddle. Also make sure all pushrods are not bent by spinning them, and use your bore scope to inspect the lifters below for signs of wear or collapse or becoming unseated.
-Buy a set of valve keepers. You will lose at least one. Use the valve spring compressor and a long narrow magnet. I tried the thing you whack with a hammer and it sort of worked, but I was nervous swiging a hammer around in there, plus I don't think you would be able to get to cylinder 6 with it.
-Lube everything up with oil upon reassembly. I also used assembly gel to help hold the valve keepers on the valve when I went to uncompress the spring.
-I highly recommend the "rope trick" to keep the valves up fully closed while you work on the springs to keep the valves from falling into the cylinder and to keep the valve up higher to make spring removal/install easier.
-Definitely go once cylinder at a time, in firing order, to minimize hand cranking the motor. Definitely torque the rocker arm bolts to spec for each cylinder at its own TDC after compression
-When removing the old bolts/grommets from the valve cover, rettain and clean the aluminum grommet inserts to re-use. The new valve cover gasket should come with new rubber grommets.

By the way, this is a BIG JOB if you are not a mechanic... In addition to that there is a lot of very old very brittle wiring being manipluated here so be very careful not to create more problems for yourself by breaking a connector or causing a short.

Before putting the valve cover back on I hand cranked the motor 6 revolutions and had my buddy watch the push rods and valve movement, give a spin check on the rods, and watch/listen/feel for any unusual noises or binding. Once I was happy with everything, I hooked up the battery and cranked it over with the starter to further verify everything was assembled correctly. Just before putting the valve cover back on, go through the firing order TDC again and re-check torque on the rocker arms.

Put it all back together. and start it up, let it idle up to temperature. Use your long magnet or some other listening device to go all around the valve cover an listen for noise. In my case I was only able to hear the oil movement in the valve train. No clicking, rattling, etc. Also check around your valve cover gasket for leaking. Re-torque valve cover bolts as needed.

While I was at it, I replaced the idler pulley and tension arm/pulley and belt. Not related to my issues but the belt was cracked and my tensioner pulley was noisy and failing.

RESULTS
-It had 1/4 tank when I started her back up, I put a pint of marvel mystery fuel treatment and filled her up witth fresh gas
-Been driving it around with the live data scanner showing misfire counts and I am getting zero misfires anywhere now
-No check engine light, I even had to daily drive it some due to my truck being in the shop, 2 weeks and counting
-I do have a lope/rough idle that only kicks in after it comes up to temp, which I will start a new thread on, this one is getting long...
 
Summary and lessons learned

Through this process I was able to diagnose and repair several issues that were contributing to my symptoms
-incorrect spark plugs and improperly gapped - diminished misfires but not fully solved
-dirty IAC cleaned - SOLVED idle surging after warmup
-several small vacuum leaks - made idle smoother but not fully solved
-faulty B2S1 oxygen sensor - diminished rough idle and misfires, but only temporarily after each PCM reset
-cleaned some very nasty injectors, and replaced some damaged injector o-rings - ran better overall and better fuel economy but still did not solve main symptoms
-throttle body clean and worn shaft repair - ran better overall and better fuel economy but still did not solve main symptoms
-leaky valve stem seals - SOLVED misfire issue on cylinders 1 and 6

I also did a few things that probably weren't necessary... but they were all a calculated move on my part not a blind spend.
-replaced coil rail without really any evidence it was bad - did this while I was doing spark plugs
-replaced IAC - did it while I had throttle body out, probably not necessary but this model is difficult to do without removing TB
-replaced fuel rail with older unit (schraeder valve) and installed the DEI heat wrap kit - the fuel rail made it easy to test fuel pressure/leak down issues

Overall I would recommend everyone get a live data scanner, bore scope, and field service manual on day 1 of digging into one of these. Change one thing at a time if possible, and try not to throw parts at the problem (especially replacing good OEM parts with inferior new parts)

If I had to do all of this over again I would probably have done the compression test and bore scope on the first day when I did the new spark plugs. And if you have a compression issue do the leak down test to determine what it is.

Still have a bit of a rough idle, which I will start a new thread on...
https://wranglertjforum.com/threads/2005-tj-4-0-lopey-rough-idle-only-after-warm-up.83095/
 
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little update on the thread from my side as well: after I bought new ignition coil pack and new injectors, I also changed the new battery that I installed with my old Optima Yellow.
as a result, I am not having misfire/CEL since then. This weekend I'll anyway mount the new stuff, but it is possible in your opinion that a battery can be related with misfire?! I doubt but it is what it is...
 
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follow up on my weekend of works around the jeep: disaster!

after the old optima yellow installation, the jeep was running smoothly and no CEL/misfire for a whole week and in every condition. I was an happy man...

I decided anyway to change all the usual P030x things with new ones: Coil pack with brand new Hitachi, brand new fuel injector bosch 4 holes and result was terryfing: the jeep wouldn't run smoothly at all.
it seemed an old 70s v8 and was not accelerating properly.

after 3 tentatives of mixing new coil with old injectors, old coil with new injectors, new + new and nothing was working properly, I decided to go back to old + old and the jeep came as it was when I started my works in morning.
test drive on the road for 30 mins, from hard acceleration to low rpms and it was perfect....

how's that possible???
more than this, I discovered that on my jeep swapping injectors cable makes no difference, unsure this is normal.

furthermore, when I was parking back the jeep before ending, I heard in the background a noise of sgrunting V8/irregular idle which was not reassuring me...
I'll be in Paris for the full month, so won't be possible to work on the jeep...I left italy sad!
 
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Novak Conversions Jeep Wrangler TJ radiator