v6 to 5.3 swap PCM might be bad???

[brandon6.0]

hey I just got done swapping a 2005 Silverado v6 to a 2002 5.3. We used a 2004 dbw harness that I had originally and used his v6 pcm. The v6 pcm are all dbc so I added the tps and iac to the 04 harness to keep his dbc. I thin looked up a matching 2005 express 5.3 van tune and segment swapped the engine side with a "write entire". After doing all this I went to start the truck and all is does is turn over and crank thin stops. It does this as long as u try it. Never had one do this. (by the way battery and all fuses are good). We checked over everything even park/neutral safety switch and couldn't find any issues with it. So we figured something has to be up with the tune or pcm. I looked over everything and cant come up with nothing. I turned off all cods, vats etc. for the swap. Still no fire.

So, my buddy went and borrowed a 2004 pcm from a friend to try. We installed pcm and truck started up and ran until vats kicked in. We were surprised it actually started. So as to my question what could be the cause of this? Is the other v6 pcm bricked and unusable? or should I try another different segement swap into it? thanks in advance.

[Ely907]

Did you check you injector firing order and did you add for the extra wires for the injectors

[brandon6.0]

yea all that was good. I added an original 5.3/60e harness I had laying around from another Silverado. It had all the necessary hookups for plug and play for the v8 swap. Hines the reason it will start up with the borrowed pcm that we tried out. so the harness and all wiring is good. But with the original v6 pcm that I had tuned for the swap wouldn't but barely turn the engine over by the starter. like only a inch of a turn at a time. like an attempt to turn the motor over and thin recognized something wasn't right and would fully turn over. we even jumped the starter relay and had it spinning over just fine, but it still wouldn't start. so we tried starting fluid without any luck. so that tells me that even when we had it turning over the injectors and coils were off. I checked codes and only had one code for crank relearn needed. but I needed to start it up to initiate crank relearn correct? so this is why I'm asking could the pcm be fried? I drove the v6 Silverado into the shop before performing the swap. so everything was in perfect order before trying to tune the pcm. beats me with whats wrong with it. I'm thinking the segment swap didn't take and I should try a different segment in it. Just don't know at this point.

[brandon6.0]

here are a copy of the stock v6 tune and thin a tune with the 5.3 express van segment added in.

[brandon6.0]

ok got it figured out and got the stock v6 pcm to work. I ended up having to do a write entire with another express van tune and it worked. everything is good to go now. thanks.

[travisn]

Some of the express vans have a different ignition system (optispark??) and won't properly fire individual LS coils, only #1 (but not at the right timing, seems 2-3x too fast). I ended up writing a camaro tune and it fired.

[Jon S.]

Both of the tunes that you attached in post #4 have the Low Resolution CKP active. That setup was originally paired with a distributor - which is why the individual coils would not work correctly.

[Jon S.]

Some of the express vans have a different ignition system (optispark??) and won't properly fire individual LS coils, only #1 (but not at the right timing, seems 2-3x too fast). I ended up writing a camaro tune and it fired.

1996 to 2002 full size vans with the Gen 1 SBC engine used a Low Resolution CKP and a distributor. 2003 to 2007 full size vans with the Gen 3 (24x CKP) engine used individual coils.

Optispark was used with the Gen 2 SBC in the mid 1990s.