The new 8.1 only firing on 4 cylinders.

[gogger]

So I got it in, started on the first crank. Took it to the lake and it started right up, good oil pressure. Didn't sound quite right. Before I could run it much more it stalled and wouldn't restart. Backfired, blew the muffler off the flanges. Pulled it out and took it home. Pulled the plugs and only 4 indicated burning fuel. Then I put new plugs in and it definitely isn't firing on all 8. Starts but running rough. Checked all the connections. Guess I need a MEFI 5 scanner tool to see if it is throwing codes. Any other suggestions while I try to find a scanner.

Bad coil packs? They are brand new I believe.

Just grasping at straws.

[michael hunter]

What fuel and ignition system are you running?

[cadunkle]

Any other suggestions while I try to find a scanner.

I know what I'd do to fix it...

[wotan2525]

I know what I'd do to fix it...

If the only tool you have is a hammer, every problem looks like a nail.

[Moor]

Lots of funny in this thread so far lol

[gogger]

I think it would be hard to find a carb and distributor for the 8.1. It's fuel injected and no distributor. I guess the ecm controls everything. Really a let down after pulling some late nighters and getting it installed. Then a ignition problem. Or so I think.

[gogger]

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[cadunkle]

I think it would be hard to find a carb and distributor for the 8.1.

If you look on some of the go fast forums it's actually a fairly common conversion. Many people have had issues with the electronics so far as reliability and driveability, and of course past a moderate HP increase it becomes a limiting factor. Intakes are available and the block will accommodate a distributor. Not sure if the cam has a gear or not but that's an easy swap too. I wouldn't convert a perfectly good running stocker in a tow boat for the heck of it, but if I was in as deep as you are I'd definitely be upgrading while it's apart. Also if oil starvation was the cause of the original failure I'd be looking at upgrading to a larger oil pan with baffles if your primary use is surfing.

[michael hunter]

Start with the basics. Run compression on all cylinders. Compare the 4 that fire to the 4 that don't.

[2500HD]

efi is easier to work on than you think. I put a 2004 4.1L in my 74 260z and the efi is awesome to work on, so easy.
Were all the plugs that aren't firing on one side of the Block? If so then your not getting power to coil packs or injectors. The other problem could just be a map sensor or maf sensor. From the look of the plugs i would guess map sensor.