Complex Problem

[V8_Club]

Hi Guys ,

Need your help. I know I haven't been online here for a while but the love is still there . Ok here is a rundown of the problem :

We built a 2008 GMC Sierra 1500 with the following mods :
418 L92 , D1SC @ 14 PSI , 4L80E Swap controlled via a TCI standalone Trans Computer . The swap involved us having to custom cut the driveshaft on the vehicle . The new one isn't perfect but does the job. Side Effect is that it does vibrate at high rpms. Another side effect is the we had the factory TCM unconnected . The same caused the following ECM/TCM Errors :

ECM U0102 ( Cancelled this via Hp Tuners )
ECM U0109 ( Cancelled this via Hp Tuners )
TCM P0787
TCM P0961
TCM P0973
TCM P2764
TCM P2769

The first two we cancelled the rest we couldn't. What happens is this , when we gradually increase throttle input Timing drops down to very low levels ( 4 degrees in the latest scan ) while KR gradually climbs ( 7.4 degrees in latest scan ) . Our theories behind the same :

1- The TCM DTCs are causing the drastic pull in timing ?
2- The makeshift driveshaft is causing vibration severe enough to fool the knock sensors into pulling so much timing ?

For reference WOT AFR is @ 11.1 ( we are still fine tuning it , so keeping it at this level to ensure safety and no Knock )

[TheDastardlyDuo]

I'd say that the KR is retarding the timing off the low octane table, which would give you about 4 degrees of total advance (12-7.4). There's a lot more going on than that however, the TCM DTC's are not effecting timing. You can run those computer without a TCM, it's done all the time.

The Knock sensors on Gen4 motors are very sensitive compared to Gen3 motors. You'll have to desensitize the sensors in order to get anywhere near the amount of timing you'd like too. Also 17 degrees at WOT is a lot for that much boost/load on pump gas, try about 12 degrees.

Please PM me, and I'll give you my number to talk about it over the phone.