Injector pump timing

[mapleridge]

I replaced my injector pump today. Things went well and the truck runs much better. I only had a snap-on scan tool and not much experience with it. The TDC offset is at -2.36 and the actual and desired timing are the same. I was aiming at about -1.5 but am not sure on how to do the relearn procedure. What does the -2.36 mean ? Can running it here damage anything?
thanks for any info

[w_huisman]

What year is your truck, and what model of pump did you install?

Typical TDCO operating range is -0.5 to -1.94. I don't think a Snap-on scanner will perform the TIMESET and TDCO LEARN funtions for you. Rescan with a Tech1 or Tech2. If TDCO is actually set at -2.36, rotate the pump about 1/3 of a mm to the passenger side (1mm = 2 deg, + to the passenger side, - to the driver side), perform the TIMESET function, and perform the TDCOLEARN function.

When performing the TDCOLEARN function, feather the throttle between idle and 1700 rpm to vary the TDCO. When the TDCO falls into range, hit the "accept", "ok", or "end" key to end the TDCOLEARN funtion and accept the displayed TDCO value. If the TDCO does not fall into range, shut down the engine and rotate the pump as necessary.

Be sure when performing these functions that the IAT's are 80 degrees or higher and the ECT's are 180 degrees or higher. Not having the engine properly warmed up to these values may be the cause for the eroneous -2.36 TDCO value you read previously. If that's true, rescan before you rotate the pump so we truly know how far to rotate the pump.

[mapleridge]

Thank, the truck is a 1996 K3500 with a 5521 pump and new FSD. All readings were with the truck at operating temp above 170. Will it hurt anything to run it like that or is it more of a fuel efficincy thing? What does the TDC offset mean?

[w_huisman]

I'm not sure what the ramifications are of running at that retarded of a TDCO. Someone else will have to chime in.