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Discussion Starter · #1 · (Edited)
Problems tuning 426. Cam timing?

So my Jeep's been in the shop for the past 3 1/2 weeks for my 426. Engine cam out of an LX, low miles, ran great the vast majority of the time, but occasionally died at stop lights, nothing real serious - we always figured it was the tune, which was done at a Mustang performance shop. Later when we pulled the fuel rails we found that 4 injectors weren't flowing for shit, figured that didn't help anything. :D

Fast forward: the last week has been all tuning. Shop kept saying that they're having problems keeping the Jeep running. I went by and checked it out for myself; Jeep starts up fine, idled a little high - around 900 RPM, revved nicely, put it in reverse, fine. Put it in drive, a little stutter, but fine. Adjust tune to drop idle, take it around the block, struggles at lower RPMs. Bring it back in, tweak the tune, start it - stutters, dies. So I contact Johan, no doubt he has a base tune that will at least get it running a little better! Downloaded Johan's tune, surge, stutter, die. Start, high idle, shift to reverse, takes a second to engage, then stutters, rev to keep it alive, idles high, shift to drive, takes like 5 seconds to engage, stutter, die.

Tuner at shop says, "I think it's the throttle body and/or the cam." The TB is a MM 85mm, the cam was from Inertia - 230/234 .556"/.556" on 114 LSA. While I personally don't think it has anything to do with the TB, or the cam's specs, I do think the timing is off. I think Stu would have degreed the cam when building the engine, but something just seems off. Original engine owner said he always idled at like 1,000 RPM, that the guy who tuned it had to keep it that high for the thing to run. New cam and Apaches are on the horizon...

Anybody have insight? Thoughts? Maybe it just needs to sit at a higher idle with that cam? Maybe timing's off?

Much thanks fellas.
 

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What fuel injectors are in there? My 426 idled around 750-800 for reference.
 

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Discussion Starter · #3 ·
Siemens 80lbs. All of them seem to be flowing properly, but they had to be scaled way down. What did you use?

750-800!?

Damn it. I have to order my cam and Apaches from Andy...if nothing else it will be an excuse to get 'em! Maybe solve this problem at the same time.
 
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