.tun file help for 98 ~ 00 Black Box 5.7 Vortec / 4L80E

[dave w]

PM Lextech for a diagram, he's got them all dialed in for the 0411 swap, probably very easy to go 97 to 98, same plugs. little wiring change, PCM looks the same and drops in.

Excellent suggestion. If this was the original 1997 Suburban that I was converting to the '0411, I think Lextech diagrams would be used.

I've been thinking about some of the differences that might not be in Lextech diagrams, because of this diesel to gas conversion. The donor 1997 Suburban wiring harness is for the 4L60E transmission and the 1998 K2500 has a 4L80E. There are going to be some changes required in the donor 1997 Suburban wiring harness because of 4L80E transmission. The diesel computer is under the dash, so I'll need to splice some of the diesel computer wiring (TOSS, TISS, & VSSB comes to mind) from the old diesel computer into the donor 1997 Suburban harness.

dave w

[EagleMark]

Oh... wow... didn't realize the diesel PCM was different location, so gas motor and harness and PCM relocate? Big job...

Ahhh... doesn't the diesel use a different TCC? Stall speed?

[dave w]

Oh... wow... didn't realize the diesel PCM was different location, so gas motor and harness and PCM relocate? Big job...

Ahhh... doesn't the diesel use a different TCC? Stall speed?

Yes, big job.

I don't have the program downloaded from the diesel computer, so I'll need to do that and check the TCC parameters. Thanks for letting me know there might be difference.

dave w

[EagleMark]

I don't think stall speed is a PCM function? Have to check tranny specs on TCC. IIRC diesel TCC stall is much lower then gas...

[bmc10258]

The diesel converter stalls a little lower than what would have come in that combination from factory. Even the factory converter stalls two low and makes the engine work just to pull away from a stoplight.

This past fall I rebuilt my 4L80E in the 98 K2500 because I broke the reverse band. I used a reman converter from a 99 G2500 van with a 4.3V6 and 4L80E. The converter code is B82. This is the highest stalling converter from factory for a 4L80E that fits the L31. You need the 6 Lug flywheel which you should be using anyway when swapping to the 4L80.

This was by far the best mod I have done to this truck. It gets up and goes at any speed and shifts and locks up perfect with the factory PCM and factory tune. With no codes.

[Hog]

The diesel converter stalls a little lower than what would have come in that combination from factory. Even the factory converter stalls two low and makes the engine work just to pull away from a stoplight.

This past fall I rebuilt my 4L80E in the 98 K2500 because I broke the reverse band. I used a reman converter from a 99 G2500 van with a 4.3V6 and 4L80E. The converter code is B82. This is the highest stalling converter from factory for a 4L80E that fits the L31. You need the 6 Lug flywheel which you should be using anyway when swapping to the 4L80.

This was by far the best mod I have done to this truck. It gets up and goes at any speed and shifts and locks up perfect with the factory PCM and factory tune. With no codes.

That 4.3 TC behind teh V8 trick is a good one. I did the same thing with my 4l60e in my 97 Vortec 350 rcsb truck. I used the 4.3 DBLF TC and can brake stall to 2800rpm, much better launch and about 400rpm less rpm drop at the shifts which helps smooth out those big ratio changes of teh 4l60e.
Just imagine when yupgrading to an actual performance TC.

peace
Hog