timing is 2 degrees less in the entire table in vcm scanner

[82LSxC10]

New to tuning and my first post here, been messing with hpt for about a year now and tuning my own vehicle setup is just a 5.3 headers and 224/230 cam truck runs good and drivabilty is good, truck runs in SD closed loop logged with a aem 30-0300 ve table is around 5% err or less in most areas its good enough to cruise around 14.7 and wot is around 12.2, also 93 oct fuel anyways what im trying to figure out why timing in the vcm scanner shows about 2 degrees less then what im commanding in the spark tables, both high and low spark tables are the same and im pretty sure base corrections are not interfering with it either, for example im commanding 25* at 5600rpm at .70 cylinder air mass and the vcm scanner shows 23.5 degrees at that range with no knock to reduce it to that value not sure what it could be at this point, any info or pointers on where to look?

Log and Tune file posted below

[blindsquirrel]

Why was injector flow rate changed from 33 to 30lb? Injector data should not be used as a tuning aid.

[82LSxC10]

Yes it was changed to 30 it has 12580681 injectors with nnbs intake

[blindsquirrel]

But none of the other injector data was changed, everything but IFR is still L59/'Z'.

[82LSxC10]

yes i understand no other injector data was changed exept flow rate but fueling isnt really my issue here, unless that some how effects the actual timing that the vcm scanner shows

[2xLS1]

yes i understand no other injector data was changed exept flow rate but fueling isnt really my issue here, unless that some how effects the actual timing that the vcm scanner shows

No it doesn't.

[82LSxC10]

No it doesn't.

thanks, still stumped on whats causing a 2 degree difference from main spark tables to actual spark in the scanner? loose timing chain? cam off a tooth? The master enable for flex fuel is still enabled but that dosent seem to do anything as i dont have flex sensor nor does it add any timing from the flex base tables

[blindsquirrel]

The spark timing displayed in the scanner is only what's commanded, it has no way to check when the spark actually happens.

To check if commanded matches actual you'd have to rig up a pointer and mark balancer for TDC and check it with a light.

[2xLS1]

The spark timing displayed in the scanner is only what's commanded, it has no way to check when the spark actually happens.

To check if commanded matches actual you'd have to rig up a pointer and mark balancer for TDC and check it with a light.

Pretty sure he is saying what is showing in the scanner is not what is in his HO/LO table which are set the same.

OP I can't look at your files but I'd suggest logging every PID that can modify timing if not already. eg. IAT advance ECT advance, Burst knock, etc........ There are many more.

[kevin87turbot]

thanks, still stumped on whats causing a 2 degree difference from main spark tables to actual spark in the scanner? loose timing chain? cam off a tooth? The master enable for flex fuel is still enabled but that dosent seem to do anything as i dont have flex sensor nor does it add any timing from the flex base tables

It certainly could be torque management or burst knock. Just like 2xLS1 indicated...you'll need to add all of the timing retard PID's to your next datalog to know for sure.

[82LSxC10]

Pretty sure he is saying what is showing in the scanner is not what is in his HO/LO table which are set the same.

OP I can't look at your files but I'd suggest logging every PID that can modify timing if not already. eg. IAT advance ECT advance, Burst knock, etc........ There are many more.

thanks, ill log all pids when i get a chance im thinking burst knock is coming into play even though i don't think there's any but i did a little digging and seen a post with a similar issue and some mentioned maxing burst knock cyl.air, ill log all knock pids tomorrow and see if thats kicking in.

[82LSxC10]

It certainly could be torque management or burst knock. Just like 2xLS1 indicated...you'll need to add all of the timing retard PID's to your next datalog to know for sure.

going to give that a shot tomorrow, burst knock tables are still stock ive seen some suggest to max cyl.air burst knock and zero its retard.