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Discussion Starter #1
Hey guys, well I finished my 5.9 swap into my Jeep Wrangler and after a few tweaks to the fuel sync the engine was running beautifully! I took it for a spin down the road and all was well for about 3 miles, when the engine died.

No weird noises, just dead. It did re-start, but was running very rough and there seemed to be a "ticking" like lifters or an exhaust leak. I was able to limp it home, but it has not run on all 8 since (happened on Sunday night). I haven't noticed any weird noises since then, and have narrowed the problem down to the #3 & #5 cylinders.

So here's where I'm at:
-verified cam & fuel sync timing
-checked compression on all cylinders (all between 160 & 175psi)
-inspected rap & rotor
-check resistance of plug wires
-replaced all 8 plugs (original plugs were new, but figured why not)
-removed and inspected injectors, re-installed in different locations to see if problem cylinders moved (they didn't)
-checked torque of rocker arms and inspected for proper lash
-reset computer
-re-loaded stock tune and then re-loaded custom sct tune
-checked wiring between PCM & injectors
-compared risistance of injector wiring on #3 & 5, to other cylinders
.....

Nothing has made a difference. I am getting 3 codes, none of which are related to the engine (1491, 1765, 0753).

The engine was just rebuilt, and has the following parts:
-comp cams cam 0.480/0.512 205/210
-hughes air gar intake
-bore +0.030
-headers
-Accel 21lb injectors
-all new sensors (except MAP)
-All new ignition parts
-new hughes iron ram 1.92 valve heads
-headers & custom exhaust
-PCM is out of a 2003 dodge ram 1500 4x4 5.9, and has been tuned by hemifever

Tonight I plan on verifying fuel pressure, turning the engine over with the the injectors out of the intake to verify operation, adding an addition ground strap (just in case), and throwing a dial indicator on the valves and verifying the lift.

What an I missing???? Did my PCM just go crazy? Did it suddenly decide it's a 6 cylinder :jester:

Sorry for the long post!
 

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Who did the SCT tune?
I had the same problem initially when I got the 1st SCT tune for my 390. It turns out that it was running too lean, and we just had to start bumping up the fuel trim from that starting point.
 

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Mine started that way, but it moved around to different cylinders.

Hemifever did mine too. He is really good about responding to e-mails.
 

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Discussion Starter #7
Thanks for the responses! I'm dying to drive this thing!

At first I was thinking maybe the valves were sticking in the heads, but with good compression that doesn't seem likely. Now it seems like it has to be a fuel issue, when pulled the 3 & 5 plugs are not wet, maybe a hint of fuel but they are not soaked like you would expect from a lack of spark...but why would only 2 cylinders suddenly stop working?

BTW, I have verified that 3&5 are not running by checking the exhaust temperature and disconnected the injectors while running. It is still possible I am having intermitent problems with other cylinders and just don't know it.
 
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Just throwing a suggestion out there, but have you put one of the other plugs in the wire and grounded it to the engine block to verifiy spark at the plug? :huh:
 

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Missed compression in the list. Oops!

A cylinder with stuck valves could still pass compression but when you checked lash they would have been WAY off since your 1/2" lift has to go somewhere. Plugs not being soaked is a good indicator as well but them having even a hint of fuel means they may not be sparking.
 

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Discussion Starter #10
I will ground out one of the old plugs and check spark tonight.

I did hook a timing light up to the plug wires and verified power was passing through them, and am getting no misfire codes; but I suppose that tells me nothing about the strength of the spark. If it is spark I wonder what could possibly cause a poor spark on 2 cylinders all of a sudden that is NOT a damaged distributor cap, bad plugs wires etc.
 

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Discussion Starter #12 (Edited)
No factory plug guards. The wires are new Taylor 8.2mm units, so I'd hope the boots are in good shape, but I have some extra msd wire laying around, I could make a couple new wires and see if that changes anything.

I'm making my list of things to check tonight, so keep the ideas coming. I promise once this thing is running right I'll post up some good pics and audio/video!
 

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Discussion Starter #13
Okay, so here's the update for tonight:

-Spark looks good on all cylinders (grounding out test plug on engine block)
-Fuel pressure is steady ~48psi
-Injectors are all functioning (tested with injectors removed from intake manifold)
-checked ground & auto shut down wiring
-adjusted fuel sync + & - (only made it run worse)
-Inspected valve operation with engine turning over
-Checked ignition advance on #1 cylinder at idle (~20 deg)
-....

Good compression, spark and fuel and it still running poorly! Think the PCM could be bad? What are the symptoms of a bad MAP sensor?
 

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Did you e-mail hemifever yet?

Your problem is in the tune. Give him some time to get it right. He did a great job with mine.
 
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