lm7 1-2 shift fallout
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Teching In
Joined: May 2023
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lm7 1-2 shift fallout hello all im hoping someone can help me / point me in the right direction. i have done a few ls swaps in my lifetime and this one is throwing me for a few circles so heres the powertrain info as i know it
03 lm7 / 4l60 from tahoe
rewired my own harness ( have done about 6-7 with no issues
no tuning just has security removed and speedo adjusted
truck is 1980 shortbed chevy 4x4
so the issue that my buddy is having is every 1-2 shift the truck falls flat on its face and then clears up and will go. the problem is worse with more throttle then less but will do it regardless.
i have a file logged of the issue and am more then happy to answer any questions. thank you!
03 lm7 / 4l60 from tahoe
rewired my own harness ( have done about 6-7 with no issues
no tuning just has security removed and speedo adjusted
truck is 1980 shortbed chevy 4x4
so the issue that my buddy is having is every 1-2 shift the truck falls flat on its face and then clears up and will go. the problem is worse with more throttle then less but will do it regardless.
i have a file logged of the issue and am more then happy to answer any questions. thank you!
TECH Addict
Joined: Aug 2005
Posts: 2,305
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From: Monroe,NY
Does it have the flex fuel injectors and is the fuel system a return style setup? The injector data in the tune says you have 33 lb injectors and the LM7 didn't use that size unless it has the flex fuel injectors..
TECH Addict
Joined: Aug 2005
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From: Monroe,NY
I would also fix your spark tables where it does the 1 2 shift. You can see it drops from 35 to 3 during the shift. that would cause a big bog. And going by the spark table in your log you can see where it actually hits -5 degrees.
Thread Starter
Teching In
Joined: May 2023
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Idk much about the swap, it came from an 04 tahoe but I'd guess they're flex fuel ones. That tune has never been touched to my knowledge besides removing the security. Could something be causing this spark drop?
TECH Addict
Joined: Aug 2005
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From: Monroe,NY
If you look at the scan when it shifts it goes into a part of the spark table that is a very low number or a negative number. I would fix that part of the table. Also do you have vss hooked up? If it doesn't know the speed it will not work properly.
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Thread Starter
Teching In
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Yes I have the speedo hooked up it showed on the logged file. I just looked at the tune file and used a compare file to a "stock upload" from hp tuners and I don't see any part of the tunes that doesn't really line up for stock. I must be missing something. I also appreciate your help
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TECH Enthusiast
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excessive torque management?
knock retard due to some noise with the shift causing false knock?
did you put new spark plugs in it? i had a 5.3 making me chase my tail once with tuning issues etc, turned out to be junk plugs the whole time
knock retard due to some noise with the shift causing false knock?
did you put new spark plugs in it? i had a 5.3 making me chase my tail once with tuning issues etc, turned out to be junk plugs the whole time
TECH Addict
Joined: Aug 2005
Posts: 2,305
Likes: 126
From: Monroe,NY
Look at the scan spark when you shift 1-2 on the spark chart and you will see where it goes in the spark table which is a very low or - spark number. Not sure why it is going in that area during 1-2 shift but i would fix that area of the spark table in the low and high octane tables.