My ls1 engine swapped earlier corvette runs 16-18 total timing all the time. It NEVER goes out of low octane timing map ever,

I still have 20 DTC check engine codes for all the stuff that isnt used anymore on my swap. But what can cause it to stay in this low timing setup?

 

Probably due to intake air temperature or coolant temperature. There is a table where you can zero out the intake air temp corrections in LS1 Edit. Only way of getting around coolant temps is to run cooler as far as I know.

 

The direct reason for falling into the low octane
mode is persistent knock detects. These, from
either real (tuning needed) or false (sensors
too sensitive, engine internal or external
mechanical noise) knock.

I would start with reading and checking off the
20 codes and see if any of them pertain to knock
sensors being out. Then, some basic check of
mixture and trims. If these look proper then I'd
try chasing false knock which, given a full
mechanical swap, could come in from hard motor
mounts, exhaust banging, who knows?

 

I would suggest making the 2 tables the same or very close to each other. Have you been Datalogging? have you seen any knock? if so correct where there is pinging and all should be well.

 

IMHO this is the stuff that costs people engines.
Making the low octane timing table the same as high octane removes the ability of PCM to pull back timing to stop piston slap and causing long term damage, esp with a SC.

I have seen at least 6 C5s with trashed engines with SC and all had knock turned off

Real knock has to be dealt with and then any false knock be tuned out, not just removing the ablilty for PCM to react to real knock

 

You probably dont have the fuel level sensor hooked up to the pcm since its a retrofit. This might be why the pcm can never reset to the high octane map.