1996 Chevy Vortec 5700 (L31) engine

March 2010
Having owned this engine for several years I thought I would spend some time going through the loom and seeing if I can get it running for a bit of a challenge in picking through wiring looms.
The main thing that motivated me to get on with this was the fact that you can access all the service information and wiring diagrams online from: www.repairinfo.com

Engine info

Size 5700
BHP 255 @ 4600 rpm
Torque 330 @ 2800 rpm
Compression: 9.4:1
Sequential fuel injection with knock sensor
Roller camshaft

Loom disassembly

The engine came complete with the entire loom, including the speedo and even the fuel pump.

I plugged the loom into the engine and laid it all out:

This is known as the early "black" ecu with a service number of Service Number 16244210. Jet sell a programmer for it (se below) - also there is a later "silver" 411 version which can be tuned with HP Tuners using a base calibration from a 2001 GMC Savana or Chevrolet Express van

After being in denial for a little while, I realised tht the easiest way to pick through the loom was to strip all the insulation of and follow all the wires. There was a large bulkhead connector that went between the engine bay and the interior - I didn't have the wiring diagrams for the inside of the car - so I traced each cable one at a time to be sure that it wasn't needed before cutting it out.

Essentially I removed the rear 02 wiring, the wiring from the transmission position selector (neutral lock out) and the air conditionning wiring.

It runs!

Here's a short clip of the engine running:

I'm currently open to sensible offers on this complete engine package (less the torque convertor and transmission) - as I fancy another engine project. As you can see, its a complete running engine with all ancilaries including even the fuel pump.

Related Links:

From my research Wait4meperformance can rework the looms and modify the ECU's to run standalone.
Painless wiring sell a loom also.
Vortec L31 full description

Jet Dynamic Spectrum Tuner which appears to provide everything you need to remove the o2 sensors etc:

DYNAMIC SPECTRUM TUNERS - Designed for the performance enthusiast who wants total control of their vehicle's programming, the JET Dynamic Spectrum Tuner is a powerful tuning package. JET’s DST software provides you with the tools needed for precise performance tuning using your laptop or PC. Use of this software will give you the ability to modify virtually every aspect of the vehicle’s programming.
Stock programming from the vehicle is initially downloaded and saved to your PC using the supplied JET interface cable that connects to the vehicle’s diagnostic port. The stock programming can be reloaded to the computer at any time to return the vehicle’s ECU to its original state.
The comprehensive, easy to use software allows extensive modification to the vehicle’s software. This allows control of fuel and spark tables, speed and rev limiters, transmission functions, torque management tables and many other functions. Modifications are made using detailed table and graph views for easy and accurate parameter editing. Your modifications are saved as a new file and downloaded to the vehicle’s computer.
DST Gas Part # 14005 Programming Options Include:
Fuel parameters including power enrichment and volumetric efficiency Ignition tables including spark advance versus load, knock retard and more
Transmission shift points, shift pressures, and TCC apply and release Diagnostic tables including fuel and air, ignition and emissions controls
Speed calibration tables to correct speedometer and shift points
Idle controls, fan temperature settings and torque management tables Raise or lower speed and rev limiters
Disable factory diagnostic trouble codes

DST part number 14005 will program the following vehicles:
1996-2000 GM Trucks & SUV's with Vortec 4.3, 5.0, 5.7 & 7.4L
1999-2006 GM LS1 Trucks & SUV's with 4.3, 4.8, 5.3, 6.0 & 8.1L
2002-2005 GM/Chevy Envoy & Trailblazer 4.2L
2002-2004 Oldsmobile Bravada 4.2L
2007 Sierra/Silverado Classic w/ LS1 4.3, 4.8, 5.3 & 6.0L
1996-1997 Camaro, Firebird, Corvette & Impala SS LT-1
1997-2004 Camaro, Firebird & Corvette LS-1
1998-2002 Camaro, Firebird 3.8L
2004 GTO LS1
2004-2005 Cadillac CTS-V

Comments, questions or got answers? Please use the Mez Forums to get in contact or chat about this page.