I jumped into the whole LSx thing with both feet. Stuck a 5.3 and T56 in my 1998 Ford F150. I used a stand alone harness. I have not worked out interface details with the speedometer so my Output Speed Sensor or VSS is not hooked up. Will this affect the performance of the engine? Does this sensor need to be hooked up to allow other engine functions to operate correctly?

 

I did 2 swaps, a 6.0 and a 5.3 both with manual trans. No VSS hookup to the ecu caused stalling issues on both. This happened primarily when depressed the clutch and coasting down from hiway speed.

 

+1 to this... most efi cars need it to keep from stalling, just wish I knew why the ECU just wouldn't keep it running on its own.

So yes, keep the VSS connected to ECU.

 

That accounts for my problems. Thanks!!