L29 0411 Swap - Struggling with crank relearn and P0300

[Reluctanse]

Need a real test drive to confirm but I'm out of time at the moment... it appears fixed.

What did I do? Loosened and adjusted the distributor, the book said go counter clockwise to add offset. Well I did while running the truck and logging, and it made it worse, so I adjusted it back.

From there basically I loosened the distributor and fiddled with it while it was idling, and eventually got it to stay at pretty close to zero. Tightened it back up, did a crank re-learn again just for fun, and it seems good to go.

How did it get out of whack? Will it stay fixed? Time will tell... I need to go on a good 30 min drive out the back roads and I'll feel good that it's dialed in.

Thanks everyone for the help.

 

[letitsnow]

The only sure way to test this is by doing a big smokey burnout, and you might as well record it for us.

 

[Reluctanse]

The only sure way to test this is by doing a big smokey burnout, and you might as well record it for us.

you're not wrong-

 

[Mangonesailor]

What's the offset now that you've done the relearn?

 

[Reluctanse]

What's the offset now that you've done the relearn?

Right around 0, +/- maybe .2 either way, just running in my driveway between 1-2k rpm’s.

Hopefully go for a meaningful test run and log tomorrow or Wednesday after work-

 

[Supercharged111]

Right around 0, +/- maybe .2 either way, just running in my driveway between 1-2k rpm’s.

Hopefully go for a meaningful test run and log tomorrow or Wednesday after work-

Spec is you set it at 1000-1200 RPM, it shifts just a little when you come off idle. I use the bidirectional controls to make it hold 1100.

 

[Reluctanse]

So, for anyone finding this thread in the future with relearn issues, I would say mine is resolved. I can do the relearn at will. My issue was having the rev limit too low, and having stored SES codes while attempting the relearn. I should also note I do NOT need to ground any pins to get the relearn to go, but do need a foot on the brake, as noted in these instructions:

https://www.gmt400.com/threads/bowtie-brodys-namesake-96-454.37609/post-1245947

Still experiencing misfires, especially on #4, but at this point, safe to say not a 0411 or crank relearn related issue.

Might start another thread on it. While warming it up and refilling my coolant for the millionth time (see my build thread if you care for the story) got a flashing SES light with a p0300 and a #4 misfire code. Both cleared up, and the truck actually drove great on the way home.

This is now mirroring an issue I had before the 0411 swap, that I had written off to old spark plugs.

Probably going to swap the OEM distributor back on and go from there… but before I do that, would I be likely to see a problem like this from a bad distributor?

 

[Mangonesailor]

I've heard of dizzy caps developing internal cracks (even new) and cross-firing, maybe there's a bad trace/joint in the cap?

Got another one to try and put on? You said you swapped wires already, right?

You make another log yet to send me?

 

[Reluctanse]

I've heard of dizzy caps developing internal cracks (even new) and cross-firing, maybe there's a bad trace/joint in the cap?

Got another one to try and put on? You said you swapped wires already, right?

You make another log yet to send me?

Not yet, the water pump saga has kept me from driving it more than about 8 minutes at a time. But I think that’s behind me….

I swapped in a new UMP distributor after I bought the truck because I scared myself into thinking the stock one needed to be replaced… it looked fine when i took it out so i stuck it on the shelf… cap and rotor are new with the distributor. I didn’t put a lot of miles on the truck with the old distributor, so not definitive, but all the misfire issues I’ve had are after i installed the new one.

I’ll make a decent run log here in the next couple days hopefully and send over to see what you think.

 

[92GMCK2500]

My bets are on the new dizzy being the culprit!