EFI Live Tuning Issues - Race Application

[Boyes50]

Hey Guys, Looking for some insight on a tuning issue I'm having with my LS Powered Sled Pulling Truck. First, background on the truck.

2004 Silverado 2500HD, Stripped and Cut Down Competition Truck and Chassis. 4L80E Manual Valve Body. FTI 5,500 9.5" Non Lockup Converter. Pulls in 1st Gear and 4LO in the Transfer Case.

Engine is a LQ4, 230s and .625 Lift Cam, 799 Heads, NNBS Intake, OEM Exhaust Manifolds for Rules. Engine dynode 430HP @ the wheels on a Non-Load Dyno. EFI Live Tuned. VP MS109 Fuel, 50# Delphi Injectors.

Engine runs amazing without load. Running it in the driveway and even hooked to a backhoe in a field, truck redlines to 7,500 and sounds perfect. Zero knock, Zero hesitation. Engine just flat out runs.

Hook it to the sled, and apply engine load, and you can watch the timing curve drop. Without any recorded knock, as soon as the tires get a hold of traction and feel the weight of the sled, the timing automatically drops to 10 Degrees. We have the Knock Sensors and Knock Retard tables turned down and set to 0, but still see this drop in timing.

Any ideas or anyone else ever seen an LS Based Vehicle drop to a constant 10 Degrees of timing under severe load? And, how do I post an attachment so I can share my EFI Log and Current Tune from the last pull.

Thanks for looking!

[joecar]

The sled places a huge load on the engine vs no load...

the higher load translates to higher g/cyl, and this in turn looks up further along the spark table axis, and spark goes down as you go along the axis.

Post your tune file and some log files.

[Boyes50]

How do I post them as attachments? I apologize as I am new here. Unfortunately I don't do much of the tuning myself, but my tuner is busy this week and I have a pull Saturday night

[joecar]

Below the reply box click Go Advanced, start your reply, click Manage Attachments...

~ posted by phone ~

[Boyes50]

21244212452124421245

[Boyes50]

Joecar, That is the current tune file and log from my last attempt to pull.

A couple concerns we have.

1.) The Wideband LM-2 Shows the correct AFR, but when I plug it into the bottom of the V2 and attempt to log it, it never reads the correct value.
2.) I'm not sure the engine is going into PE Mode, as the Commanded AFR does not change much if any. Last season, My Commanded AFR went from 14.52:1 down to 12.8:1 when I went WOT.
3.) You can see as soon as the engine gets up to snuff, the PCM pulls all the timing and it falls on its face. It still holds around 4,500RPM, but loses all power