383 stroker

[bamcis]

Have you tried switching plugs in #5 cyl? If the misfire code follows that plug then bingo! I had this happen on my truck. Plug looked like new but for some reason was causing misfire. Replaced and haven't seen code since.

 

I'm sure you read that it could be the mechanical SFI (spider ) fuel injection. You can upgrade that to electronic MPFI for about $300 ~ $350. I'm still running the old SFI injection. Everything works good except cold starts it tends to flood the engine a bit on first start.

 

 

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Been awhile since I've logged on. But I'm still getting the pesky code. Especially when I go into states with 80mph speed limits.

 

I "upgraded " to the MPFI when I swapped the motor out.

[sputtle]

Have you tried anything to rule out the issues lately?

 

I think you're on the right track with a software problem. I don't see why anything should be causing a misfire on a new engine at that RPM, other than a fuel pump going out. But I'm thinking you've probably already replaced that. If all the commons are already resolved (fuel pump, filter, regulator and injectors,) then I would recommend taking it back to the dyno and start over. Even going as far as using a stock tune (if it would even run on that, I wouldn't know) and see if the misfire is gone. If it is, start your tune over again. I think you'd find some good results there.