l83 2016 in a 67 c20 misfire issue

[c20]

l83 and 6l80e. Its a low RPM misfire, it is running driving but badly with an intermittent misfire.. I bought hp tuners but need some help with a tune.. Can i export something so folks can see what it has as far as tune, in over my head on this side, i was thinking about trying to work on the tune myself, but after reading some of you guys, maybe i can get some help on it.. Its running a gm mu2101 zl1 fuel module with a controller and harness made for a swap.

l83 / 6l80
4:11 gears
2.5 dual magnaflow
shorty headers
big k&n cold air intake and thats about it as far as custom touches..
drivetrain has 30,000 miles.

really just want it to run in a strong reliable way, not looking for too much more..
thanks in advance for any help or ideas
Zach

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[Robert C Morgillo]

c20, I have a similar issue with a 2016 L83 in a GMC Sierra. I am pretty sure I have a bad coil pack. Though mine only has 44,000 miles on it, there have been a few intermittent failures of coil packs noted on the internet forums. If I am cruising and it is in high gear at low RPM and the converter is locked up, when I try to lug it it will buck. If I keep it up long enough it will set a temporary check engine for misfire. The more moisture there is in the air the more it will act up. It is progressively getting worse. The problem now is which coil pack?

Do you think it could be a coil pack? I will also tell you the control module under the coil pack is sensitive to voltage spikes. More than one has been ruined while swamping LS's around!

I am hoping one of the members can help with using the scanner to detect which cylinder is actually misfiring.

[Ben Charles]

Scan cylinder misfire and look at Each cylinder (you will have to to add these to the channels)

[c20]

Might be the coil, it does seem like an electrical thing but i dont know.. I did put a physical gauge on the fuel pressure (old school i know) that was bouncing around , but it did read 45 psi which at idle i think is right, i will find it in the program and look further and try to run the scan on the misfire.. Back to the manual.
thanks

[c20]

here is the tune thats on it..
i did notice that it has a 2017 ecm that came with my harness and the engine is a 2016, should i worry about that?
it did cost more credits..
c20 full tune.hpt

[JKLTGuy]

I put a 2016 L83/8L90 in a 2008 Jeep. I got the engine with 2016 harness and 2017 E92 ECU. The I/O assignments are different between the two and we had a hell of time getting it to run leaner. Also did not see the fuel rail pressure signal. Turned out we put a 2016 ECU in and it started like it had been running for 10 years. I paid 4 credits to access that 2017 ECU and had to throw them and buy 2 credits to access the 2016 one and I already paid 2 credits to access the Jeep side to kill some stuff there. I can say there is a difference between years of Chev engines and harnesses with them. Why I don't know because the engines are the same.

[c20]

can someone look at the tune above.. I posted it a few days ago, apparently the tune on my engine is a 2014, but the above one i registered somehow with 4 credits .. I have only ever plugged into the obd of THIS vehicle in the few days i have owned HP tuner, nothing else. they want me to pay again but i am not clear on how this was registered, where its from, or how that happened and no one is explaining it to me.. Does it look like it was saved from a car or can you tell? I get the thing where they should be paid for usage, but in this case it literally for nothing, so i am trying to figure how to approach it if i plug in again, and this keeps happening, is this something folks encounter? Might be heading to a big waste of money and these days thats an issue..

[c20]

ok figured all that out..
not sure what i did but i am fairly sure it was my fault..
still have a misfire, getting a professional tune and the tune is going well and the truck runs really good.. still have this little studder, or misfire at low rpm usually when it changes gears.. like a pop pop thing.. I am going to have the exhaust checked for a leak i think might be at the shorty header collector tomorrow, but with a really free flowing exhaust could that really change the way it runs that much? Heard about all sorts of things on here from lifters to coils, anyone have an idea? thank you

[5FDP]

You sure it's a misfire or is it just when the computer pulls timing for the shifts?? No cats or resonators will let you hear everything when it retards the timing a lot.

If this was my vehicle I would disable the torque converter completely for gears 1-4 and only let it engage in 5th and 6th gear. It makes city driving way better.

[c20]

thanks, it is pretty consistent , so i dont think so, but maybe. Its a pop pop pop misfire sound... Its there lightly when idling too.. there is a leak at the passenger side collector right before the O2 sensor, that will be fixed tomorrow then i dont know.. A coil? Seems to be on the passenger side

[c20]

Also can I rule out the afm lifters if the misfire is intermittent?

[c20]

if anyone has experience with l83 misfires, please chime in.. I have heard injectors, coils etc.. for some reason were not getting misfires as trouble codes and i am about ready to do a dod delete conversion on this engine to get rid of it, but knowing me, it will still be there after that expense in time and money.. So is there timing in the program or other that could cause it, mechanical things, other threads? any help.. I can replace things, but if anyone has experience of good places to check, it would be a good time to hear of it

thanks for any help on it

[c20]

here is a scan of it running.....1-27 driving scan low speed shifting etc.hpl

[c20]

I drove it and got on the gas a few times and it seems a bit better, still there , but better.. do these computers "learn"? I mean for a while it actually was fine.. hmmmm.. anyone?

[c20]

finally giving a trouble code.. but a transmission one.. Could this be part of the issue? I also asked the guy helping with the tune, but thought i would put it here in case someone has experience with this..
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