LS3 - 408 Popping - 6L80e not shifting .... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

6600DURAMAX · 10-29-2024, 09:45 AM

Having two separate issues

1. Have a Blueprint LS3 - 408 - makes 595HP engine almost 400 at the wheels - running a PSI Harness and a 6L80e trans - full length headers into dual 3'' stainless exhaust with "X" pipe and 3'' BORLA ATAK mufflers. Engine has about 500 miles or so - oil changed since break in also installed new plugs and Scott's Performance wires.

Question that I have - when accelerating at roughly low to mid throttle input the engine wants to pop through the exhaust - this is especially noticeable right before it shifts. Been to the tuner twice and he states it is not running lean and that it is impossible to tune it out 100%

I'm at a lost here - thoughts suggestions.

2. Have a 6L80e behind a LS3 - 408 - the transmission has a Yank Pro Truck 3200converter in it and is being controlled by a PSI Harness

Question - if I am driving the truck normally - the trans shifts normally ( all the way into 6th gear). However if I accelerate hard, do a burnout, ect..... the trans will not shift all the way into 6th - seems to shift to 5th and just stay there. If I stop and shut the truck off, restart it and take off all seems to be normal ??
The other day the trans wouldn't shift out of 2nd gear( I think it was in 2nd) ....... drove for a mile or so - shut it off.... restarted it... all seemed fine and shifted all the way to 6th

Ideas on the cause of this ??

Any help on either of these issues ???

6600DURAMAX · 10-29-2024, 09:46 AM

everyone loves pics ....

Willie Makeit · 10-30-2024, 10:12 AM

I would find a new tuner

RustyPile · 10-30-2024, 11:27 AM

Quote:

Originally Posted by Willie Makeit

I would find a new tuner

That's also my suggestion.......

6600DURAMAX · 10-30-2024, 01:44 PM

I don't disagree with you guys - its odd however as I've known this tuner to be super reliable per a bunch of people

Anyone know a tuner in the Northwest Indiana area ??

LS3/ 6L80e with a PSI Harness

6600DURAMAX · 10-30-2024, 01:46 PM

Here is a plug I pulled

**Accelo** · 10-30-2024, 02:20 PM

Maybe this will help, some transmission tuning information.
https://www.youtube.com/watch?v=8PCjGINa100

Full throttle in 6th gear? I don't know your gear rations, but the speed has to be very high. Will the Blazer do 160mph?

You have an absolutely gorgeous Blazer.

6600DURAMAX · 10-30-2024, 03:29 PM

I'll try to clarify the transmission question - I'll watch the video, appreciate it

If I am driving the truck normally - the trans shifts normally ( all the way into 6th gear).

However if I accelerate hard from a stop ( 1st gear maybe 75% throttle) the trans will not shift all the way into 6th - seems to shift to 5th and just stay there. If I stop and shut the truck off, restart it and take off all seems to be normal ??

The other day the trans wouldn't shift out of 2nd gear( I think it was in 2nd) ....... drove for a mile or so - shut it off.... restarted it... all seemed fine and shifted all the way to 6th

LS short box · 10-30-2024, 04:06 PM

No help with the 6th gear issue but if you duplicate the 2nd gear issue with your tuner in the vehicle with his laptop plugged he should be able to see? the issue.

Willie Makeit · 11-01-2024, 10:44 AM

pic is blurry, but that plug looks to show a lean condition based on the porcelain being charred

6600DURAMAX · 11-01-2024, 12:22 PM

I agree - plug looks a little lean to me as well

**biketopia** · Yesterday, 01:27 PM

What management system is running this, holley, factory, FiTech??

6600DURAMAX · Yesterday, 06:00 PM

Running on a PSI harness with a HP Tune

**biketopia** · Today, 08:10 AM

Quote:

Originally Posted by 6600DURAMAX

Running on a PSI harness with a HP Tune

So a stock ECU, harness doesn't make a difference unless there's a mixed up wire, but you'd have a constant problem, not intermittent. I would reach out to another tuner, or even the HP tuners message boards and see if someone can look over your tune file. I'm not super familiar with HP Tuners. But your combo isn't something crazy or extravagant, should be very run of the mill. Probably a simple setting that needs to be tweaked. Also are you sure there are no exhaust leaks before, or near your O2 sensors?

Joyridin · Today, 08:46 AM

Do you happen to know what your fuel pressure is? Do you have an adjustable regulator?

leegreen · Today, 11:14 AM

Have tires or gearing been changed since the last tune for the trans? There is a different trans map for WOT, so readings may be going off the map before 5-6 shift if you have changed gearing
HPTuners has several forum posts on similar issues, read through all those and you'll probably know more than I do about how it works

intermittent stuck 1-2 shift could also be low fluid or a sticking check ball, cracked valve body...it could be a separate issue

10-29-2024, 09:45 AM	#1
6600DURAMAX Registered User Join Date: Nov 2000 Location: Wheatfield IN, USA Posts: 1,120	LS3 - 408 Popping - 6L80e not shifting .... Having two separate issues 1. Have a Blueprint LS3 - 408 - makes 595HP engine almost 400 at the wheels - running a PSI Harness and a 6L80e trans - full length headers into dual 3'' stainless exhaust with "X" pipe and 3'' BORLA ATAK mufflers. Engine has about 500 miles or so - oil changed since break in also installed new plugs and Scott's Performance wires. Question that I have - when accelerating at roughly low to mid throttle input the engine wants to pop through the exhaust - this is especially noticeable right before it shifts. Been to the tuner twice and he states it is not running lean and that it is impossible to tune it out 100% I'm at a lost here - thoughts suggestions. 2. Have a 6L80e behind a LS3 - 408 - the transmission has a Yank Pro Truck 3200converter in it and is being controlled by a PSI Harness Question - if I am driving the truck normally - the trans shifts normally ( all the way into 6th gear). However if I accelerate hard, do a burnout, ect..... the trans will not shift all the way into 6th - seems to shift to 5th and just stay there. If I stop and shut the truck off, restart it and take off all seems to be normal ?? The other day the trans wouldn't shift out of 2nd gear( I think it was in 2nd) ....... drove for a mile or so - shut it off.... restarted it... all seemed fine and shifted all the way to 6th Ideas on the cause of this ?? Any help on either of these issues ??? __________________ 1972 K5 - LS3/408 (595Hp) -6L80e-One Tons with 4.56, 20'' Beadlocks with 37'' rubber, full TMI interior, JL Audio ..... 1971 CREWMAX Build.....at body shop for couple more years

10-29-2024, 09:46 AM	#2
6600DURAMAX Registered User Join Date: Nov 2000 Location: Wheatfield IN, USA Posts: 1,120	Re: LS3 - 408 Popping - 6L80e not shifting .... everyone loves pics .... Attached Images __________________ 1972 K5 - LS3/408 (595Hp) -6L80e-One Tons with 4.56, 20'' Beadlocks with 37'' rubber, full TMI interior, JL Audio ..... 1971 CREWMAX Build.....at body shop for couple more years

10-30-2024, 10:12 AM	#3
Willie Makeit Registered User Join Date: Oct 2013 Location: Alabama Posts: 1,228	Re: LS3 - 408 Popping - 6L80e not shifting .... I would find a new tuner

10-30-2024, 01:44 PM	#5
6600DURAMAX Registered User Join Date: Nov 2000 Location: Wheatfield IN, USA Posts: 1,120	Re: LS3 - 408 Popping - 6L80e not shifting .... I don't disagree with you guys - its odd however as I've known this tuner to be super reliable per a bunch of people Anyone know a tuner in the Northwest Indiana area ?? LS3/ 6L80e with a PSI Harness __________________ 1972 K5 - LS3/408 (595Hp) -6L80e-One Tons with 4.56, 20'' Beadlocks with 37'' rubber, full TMI interior, JL Audio ..... 1971 CREWMAX Build.....at body shop for couple more years

10-30-2024, 01:46 PM	#6
6600DURAMAX Registered User Join Date: Nov 2000 Location: Wheatfield IN, USA Posts: 1,120	Re: LS3 - 408 Popping - 6L80e not shifting .... Here is a plug I pulled Attached Images __________________ 1972 K5 - LS3/408 (595Hp) -6L80e-One Tons with 4.56, 20'' Beadlocks with 37'' rubber, full TMI interior, JL Audio ..... 1971 CREWMAX Build.....at body shop for couple more years

10-30-2024, 02:20 PM	#7
Accelo Senior Member Join Date: Mar 2015 Location: washington Posts: 2,280	Re: LS3 - 408 Popping - 6L80e not shifting .... Maybe this will help, some transmission tuning information. https://www.youtube.com/watch?v=8PCjGINa100 Full throttle in 6th gear? I don't know your gear rations, but the speed has to be very high. Will the Blazer do 160mph? You have an absolutely gorgeous Blazer.

10-30-2024, 03:29 PM	#8
6600DURAMAX Registered User Join Date: Nov 2000 Location: Wheatfield IN, USA Posts: 1,120	Re: LS3 - 408 Popping - 6L80e not shifting .... I'll try to clarify the transmission question - I'll watch the video, appreciate it If I am driving the truck normally - the trans shifts normally ( all the way into 6th gear). However if I accelerate hard from a stop ( 1st gear maybe 75% throttle) the trans will not shift all the way into 6th - seems to shift to 5th and just stay there. If I stop and shut the truck off, restart it and take off all seems to be normal ?? The other day the trans wouldn't shift out of 2nd gear( I think it was in 2nd) ....... drove for a mile or so - shut it off.... restarted it... all seemed fine and shifted all the way to 6th __________________ 1972 K5 - LS3/408 (595Hp) -6L80e-One Tons with 4.56, 20'' Beadlocks with 37'' rubber, full TMI interior, JL Audio ..... 1971 CREWMAX Build.....at body shop for couple more years

10-30-2024, 04:06 PM	#9
LS short box Registered User Join Date: Jun 2015 Location: Carlos MN Posts: 2,094	Re: LS3 - 408 Popping - 6L80e not shifting .... No help with the 6th gear issue but if you duplicate the 2nd gear issue with your tuner in the vehicle with his laptop plugged he should be able to see? the issue.

11-01-2024, 10:44 AM	#10
Willie Makeit Registered User Join Date: Oct 2013 Location: Alabama Posts: 1,228	Re: LS3 - 408 Popping - 6L80e not shifting .... pic is blurry, but that plug looks to show a lean condition based on the porcelain being charred

11-01-2024, 12:22 PM	#11
6600DURAMAX Registered User Join Date: Nov 2000 Location: Wheatfield IN, USA Posts: 1,120	Re: LS3 - 408 Popping - 6L80e not shifting .... I agree - plug looks a little lean to me as well __________________ 1972 K5 - LS3/408 (595Hp) -6L80e-One Tons with 4.56, 20'' Beadlocks with 37'' rubber, full TMI interior, JL Audio ..... 1971 CREWMAX Build.....at body shop for couple more years

Yesterday, 01:27 PM	#12
biketopia Senior Member Join Date: Jul 2015 Location: Warrenton VA Posts: 1,089	Re: LS3 - 408 Popping - 6L80e not shifting .... What management system is running this, holley, factory, FiTech?? __________________ 71 c-10 Long Bed, under the knife for a No Limit Engineering Wide Ride Chassis Pack and coil over static drop. 07 Silverado Classic 2wd 95 Camaro 427SBC/TH350

Yesterday, 06:00 PM	#13
6600DURAMAX Registered User Join Date: Nov 2000 Location: Wheatfield IN, USA Posts: 1,120	Re: LS3 - 408 Popping - 6L80e not shifting .... Running on a PSI harness with a HP Tune __________________ 1972 K5 - LS3/408 (595Hp) -6L80e-One Tons with 4.56, 20'' Beadlocks with 37'' rubber, full TMI interior, JL Audio ..... 1971 CREWMAX Build.....at body shop for couple more years

Today, 08:46 AM	#15
Joyridin Registered User Join Date: Sep 2020 Location: Cleveland, Ohio Posts: 544	Re: LS3 - 408 Popping - 6L80e not shifting .... Do you happen to know what your fuel pressure is? Do you have an adjustable regulator?

Today, 11:14 AM	#16
leegreen Registered User Join Date: Mar 2022 Location: Surrey BC Posts: 879	Re: LS3 - 408 Popping - 6L80e not shifting .... Have tires or gearing been changed since the last tune for the trans? There is a different trans map for WOT, so readings may be going off the map before 5-6 shift if you have changed gearing HPTuners has several forum posts on similar issues, read through all those and you'll probably know more than I do about how it works intermittent stuck 1-2 shift could also be low fluid or a sticking check ball, cracked valve body...it could be a separate issue



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