So I've got a 2000 XJ with a Golen 4.6 Stroker. Motor has been great since I've dropped it in until about 6ish months ago when I developed a #6 cylinder misfire followed by a flashing CEL under acceleration. Since then I've thrown the parts cannon at it trying to fix it. New plugs (gapped .35), mopar crank sensor, cam sensor, delphi fuel pump (55psi), flex plate, coil rail, PCM (wranglerfix), cleaned grounds, ohmd all injector wires (0 ohms) they pulse with noid light, new exhaust from header back, new O2 sensors, big 7 upgrade, refreshed coil rail connector and all injector plugs (still pulse and 0 ohms), exhaust/intake manifold gasket, compression test (165 all 6cyl) The jeep just isn't running right, whole motor shakes at idle with loud top end noise (audible in cab at any speed). While parked and vehicle in drive it feels like it's going to stall but never does. Under acceleration, it shakes so bad from 1500-2000 rpm, but it's smooth from 2000rpm onwards. Under heavy acceleration, the CEL flashes but goes away while coasting or slightly accelerating. Current code (P0301, P0172) popped at 1800rpm with my STFT -5.5% LTFT -31.3% Things to note:While placing cyl 1 at TDC I noticed that TDC was actually past 0° about a 1/4 turn. Replacing harmonic balancer actually put TDC back to 0°. Timing chain is lined up correctly with 0° and cyl 1 TDC.I have spark (all 6 plugs tested at same time while jeep turned over, good spark all plugs)All 6 injectors click when appling 9v battery to them. No visible cracks either.The cyl misfire code seems random and travels, dumping excessive fuel where it won't ignite. Im running out of ideas as to what it could be. I have spark, fuel, and air. With winter upon us, I'm trying (been trying for half a year) to get this thing running reliably and not trash my (expensive) motor. Any help is greatly appreciated, thank you.

 

Ok, I read that many times and I think I got everything. It's a lot.

I have a few questions:

P0301 is a cylinder 1 misfire, but you say you have a cylinder 6 misfire.

The top end noise is suspect. Have you pulled the valve cover and checked your rocker arms? Wiggle them with each cylinder at TDC on its compression stroke.

What injectors are you using?

Have you tried moving components from cylinder to cylinder to see if it follows that part? For instance, swap the spark plug wire from #6 (or is it #1?) to another cylinder and see if the code changes to that cylinder. Now do the same with the spark plug, fuel injector, and even the fuel injector connector (#5 with #6, or whichever one).

Get a magnetic base dial indicator and see if you can check your cam lift by measuring rocker arm lift on each cylinder. Recently there has been a rash of bad lifter issues, especially for flat tappet cams. Maybe one of your lobes has gone flat?

 

I've pulled the valve cover and only rocker I found that was noisey was #4, but was not check on TDC for each cylinder. All was snug, except #4.

It started with a #6 cylinder misfire, but it travels to different cylinders when a code pops. After the parts cannon, it's fairly consistent on #1 now. I get a pending P0301 code with a reader and no visible check engine light on.

I believe they're bosch, its whatever Chad Golen uses in his builds, and he swears by them with his reputable engines.

I've swapped plugs and injectors, nothing changes. Recept plugs pulled showed #6 covered in gas, #3 #4 sooty, #5, #2 #1 all fine

 

I absolutely hate hate hate the parts cannon mentality. With the terrible quality of parts these days, you could be introducing extra issues and not realize it. Troubleshoot, diagnose, replace.

The loose rocker is probably your smoking gun. Check the torque of the rocker arm bolts. Lifter preload is "not" adjustable on the 4.0. If the rocker bolts are tight and the rockers are still loose, you might need to be talking to Golen.

 

I'

" I've pulled the valve cover and only rocker I found that was noisey was #4, but was not check on TDC for each cylinder. All was snug, except #4."

Doesn't mean anything if you don't check them at TDC

 

I plan to do this ASAP, work (fire/medic) is stupid busy right now (24hr shifts). Thank you all for the input on this, I truly appreciate it.

 

I do sincerely hope it's something as simple as a pushrod or a rocker arm. If your cam has gone flat, there isn't much that can be done, and the head has to come off to pull that cam.

 

Pulled the valve cover and found this, pushrod on #6 dropped down and bent. Putting new pushrod in.

 

After replacing the bent pushrod, the rocker arm to the left of the bent one will not move while turning the motor over. It is quite squishy and springy when I push down on the pushrod. While motor is running with valve cover off and pushing down on the pushrod, I can feel the cam pushing up on the pushrod. However, it's not enough lift to make contact with the valve spring.

I have tried putting marvel mystery oil down the pushrod/lifter with no success in freeing the potentially stuck lifter.

My thoughts are either a failed lifter or rounded cam lobe. Either way, head gotta come off is the next step. Will update as time permits. Got a snow storm coming in tomorrow afternoon and Fire/EMS doesnt get a break with bad weather.

 

Well, as suspected, the squishy lifter was in fact dished out and chewed up. There is a hole in the bottom and I'm going to say a new cam is in order as well.

Pistons and valves look okay to me, but obviously a second set of eyes won't hurt.

Anything else I should do while I'm this deep into the motor anyway?

 

Cam Lobe where the lifter failed is wiped. Time to pull the cam.