L29 411 Swap P0300 code

[Beeffajitas]

So this seems odd to me. I did the 411 swap several months ago. Ran fine out of the gate. I had it dyno tuned over the summer. The truck has been sitting for a few months due to a rear axle swap. Once I got it running again, it throws the Crank Relearn Code. I have HPTuners now, so I did the relearn, twice now. Now it's throwing P0300 and P0304 codes. The other day it was actually flashing the SES, which I assume means it thinks it's a really bad misfire. The engine seems to be running fine when warm. It does stumble when it's cold and I know I need to address the cold engine tune, but it doesn't throw the code then.

I'll double check cylinder 4 spark plug, etc. But, has anyone had this issue with the 411 swap. It just seems really random to me.

 

[Christian Steffen]

Did you do any other engine mods? Log your misfire counter. I'm assuming it is from have a different cam, but at idle my truck was constantly kicking up misfire count but there was absolutely no sign of a real misfire. Anyway, this would throw the random misfire code and point it to different cylinders occasionally, so I maxed out the low rpm misfire table and that fixed the issue.

Email me your log and tune if you want, I can look it over.

[email protected]

 

[Beeffajitas]

No mods, yet. Stock motor. I definitely had some misfire counts before, but it never kicked a DTC. I was watching it on the Torque app.

 

[Christian Steffen]

I wonder if with the colder weather, the engine just runs a little rough because of the tune being off, and that is showing as misfire? Watch when the misfires are happening, if it just at idle and you can't feel it, then I would reduce the sensitivity and see if that fixes it.

 

[Christian Steffen]

Curious what it made on the dyno?

 

[Beeffajitas]

Ended up at 225/330. I need to sit down and make a build thread one of these days.

BTW, I sent you my file a few hours ago.

 

[Supercharged111]

Did you copy the warmup fueling over from either the black box 454 or the 411 8.1?

 

[Beeffajitas]

Is there a copy of the black box tune floating around?

I'll grab an 8.1 tune off HPTuners and take a look.

 

[Supercharged111]

For EFILive, yes. For HPT you'd have to search.

 

[Christian Steffen]

There is a black box tune on the hp tuners website. I don't think there is anything useful in the idle airflow tables though.