My 454 Rebuild

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Spareparts

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Did not read anything about that. It almost never gets under 3/4 tank as a rule and was filled this morning from 3/4 tank.
The shop i had it at seems to be idiots. They told me it has no misfires. It does not have a constant misfire but using Dash Command i can see misfires.
Mostly on Cylinders 4 and 7 and not consistent and not enough to trip a code. Most of the cylinders have random misfires. I believe that is causing the - fuel trims.
The only thing i have not changed is the distributor but i have tried two different caps and rotors with no difference.
I also have a injector tester coming also. This weekend ill be taking the upper intake off to check each injector. I have 24 of the GM style so should have 8 that are the exact same for flow and with the intake off changing the distributor is easy.
I just can't think of anything else it could possibly be.
 

L31MaxExpress

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Did not read anything about that. It almost never gets under 3/4 tank as a rule and was filled this morning from 3/4 tank.
The shop i had it at seems to be idiots. They told me it has no misfires. It does not have a constant misfire but using Dash Command i can see misfires.
Mostly on Cylinders 4 and 7 and not consistent and not enough to trip a code. Most of the cylinders have random misfires. I believe that is causing the - fuel trims.
The only thing i have not changed is the distributor but i have tried two different caps and rotors with no difference.
I also have a injector tester coming also. This weekend ill be taking the upper intake off to check each injector. I have 24 of the GM style so should have 8 that are the exact same for flow and with the intake off changing the distributor is easy.
I just can't think of anything else it could possibly be.
My van had a misfire at highways speeds at low engine loads while cruising when the distributor drive gear knife edged. The gear did not even last 80K on my 97.

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Spareparts

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It's a new melodized gear installed with a new cam in the engine. Done it sense first start.
 

Carlaisle

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One simple thing you can try is to park somewhere pitch black, make sure every light you can turn off is off, and open the hood while it's still running. Pull the bulb for the underhood light before you start. If you see a lightning show emanating from your plug wires you likely have a bad/inadequate/missing ground.
 

ralmo94

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Did you turn the dizzy to 0° cam sync at 1100 rpm + or - 2 °?
 

Spareparts

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I don't think it's a bad ground. I have new ground wires from the engine to frame to battery and battery to body and engine to body.
CMP is -0.3 to +0.3 (ish)
Thanks for trying though!
 

Reluctanse

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I’m just going to suggest it, because it keeps coming to my mind. Is it possible there’s a damaged wire somewhere in the harness that is occasionally shorting causing this issue? Some minor harness damage that occurred during engine out/in process?
 

Spareparts

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Well until i find the problem anything is possible. That is what led me to replacing all the cables with new cables. All sensors i can monitor are working in the proper range with none being intermittent.
It does not feel like a intermittent short or loose connection. It is always the same.
 
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