LS3 - 408 Popping - 6L80e not shifting ....

[6600DURAMAX]

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]

everyone loves pics ....

[Willie Makeit]

I would find a new tuner

[RustyPile]

Originally Posted by Willie Makeit

I would find a new tuner

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

[6600DURAMAX]

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]

Here is a plug I pulled

[Accelo]

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]

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]

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]

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

[6600DURAMAX]

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

[biketopia]

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

[6600DURAMAX]

Running on a PSI harness with a HP Tune

[biketopia]

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]

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

[leegreen]

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

[6600DURAMAX]

Originally Posted by biketopia

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?

No exhaust leaks - I have ordered a Mpvi3 from HP tuners - going to plug it in and put some run time for data logging then send to another Tuner that I have found in the area. Indiana Muscle Cars - he will look at the data and make tweaks if necessary . Hopefully this fixes the popping issues

[6600DURAMAX]

Originally Posted by Joyridin

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

Yes adjustable very close to the fuel rails - set at 60psi at idle - all new fuel system - Areamotive Pump, filter and regulator with a return line

[6600DURAMAX]

pic

[6600DURAMAX]

Originally Posted by leegreen

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

No in regards to the tire/ gearing all is set for 37'' tires with 4.56 gears

I'll check fluid level

Maybe the HP Tuner will log something that is notable

[LockDoc]

-
I would try unplugging the main harness connector on the transmission and plug it back in, making sure it is seated all the way in. I was having shifting issues with my 8.1/Allison combo and that is what my problem was. Just a shot in the dark but it doesn't cost anything to try it.

[WorldsCrappiestTruck]

It sounds ridiculous…..but ohm out from the ECU, to each individual coil trigger wire on all 8 cylinders to make sure 1-1, 2-2 etc.

I bought a set of coil harnesses online somewhere, that were mis-wired. It would idle ok, drive Meh ok at low throttle then all hell broke loose at WOT.

An infared gun at idle on each header tube was the first indicator. I had say 200* on a couple runners, and 120* on 2 others.

Plugs were just firing whatever off-time residual fuel was in the cylinder. They weren’t dead, and it didn’t show up much at idle.

Maybe you have a similar situation and that’s causing stuff to go into Help Me mode and not shift right?

Just a thought….