Vortec 454/4L80e HD swapped 1999 Tahoe OBS

[bigfootchiro]

Bad news... started yesterday. Driving down road, TC won’t lockup, then soon after lose 4th gear. Did it on my way to the office, and after losing 4th, truck will hard shift through all gears under acceleration. Also, can feel it stuttering while maintaining constant speed. Fluid level is fine and doesn’t look burnt. Don’t know what the pressures are. I’ve done some quick research as to checking OD clutches, 3-4 shift solenoid. Any other suggestions? Some 4L80e experts on here?

 

[PG01]

Found a bad ground in the area of that diagram above. Just noticed it! Previous owner thought it would be a good idea to “hook” the wires together and put shrink wrap over it, but never heated it either to shrink around. Didn’t even twist the wires together. Throwing a new ground wire on and we will see how she runs

View attachment 225145

Bad news... started yesterday. Driving down road, TC won’t lockup, then soon after lose 4th gear. Did it on my way to the office, and after losing 4th, truck will hard shift through all gears under acceleration. Also, can feel it stuttering while maintaining constant speed. Fluid level is fine and doesn’t look burnt. Don’t know what the pressures are. I’ve done some quick research as to checking OD clutches, 3-4 shift solenoid. Any other suggestions? Some 4L80e experts on here?

Yeah, put those wires you took apart back together dumdum...

 

[bigfootchiro]

Yeah, put those wires you took apart back together dumdum...

Lmao too bad the transmission is doing this even AFTER putting the wire back together! Fix it for me @Galante

 

[PG01]

Lmao too bad the transmission is doing this even AFTER putting the wire back together! Fix it for me @Galante

Bring it up.

But did you not twisty them and not heat shrink them is the question......

 

[bigfootchiro]

Bring it up.

But did you not twisty them and not heat shrink them is the question......

Where you at? The ground wire is fixed now

 

[PG01]

Neuva York

 

[bigfootchiro]

Neuva York

Might blow it up on the way there lol

 

[bigfootchiro]

Here are two screenshots of PID data from a 25 minute drive. Numbers to right go Max/Min/Avg. A couple things to note: LTFT on Bank 2 Max and Average, and the Absolute Throttle Positions. At idle, the throttle would bounce between 0.4% and 0%

 

[bigfootchiro]

Here’s another from this morning. I drove around in 3rd to keep OD from kicking me back into third, and to keep it from hard shifting.

I noticed a few things... as RPMs went up to around 2500, the LTFT on Bank 2 would come down to around 9-10%, indicating a vacuum leak. If I put more load on the engine by accelerating, it would start to rise, which would indicate a fuel issue, as well. If I let my foot off, it would immediately dip back down to about 8-10%, then start rising back up. As you can see, at one point in time I did get the LTFT on Bank 2 down to 0%, but that was probably under one of my harder accelerations to see what it would do. STFT on Bank 2 is still a bit of an issue, but I think it’s related to everything else.

Thoughts?

 

[HiHoeSilver]

If I'm you, I'm looking for a fuel problem on bank 2 for starters.