$EE LT1 Tuning Questions

[Terminal_Crazy]

Q1: Is the data logging just slow or weird on the 8051 PCM.

I've got a log here , rpm's stable within 30 revs. map increases from 62 to 86 in 6 logs.
The AFR Target moves around.
OK I can understand interpolated data .
open loop AFR target at 85 map is 13.0:1
90 map is 13.0:1

so why does the target at 86 map expect 13.1 ??
.... still wading through logs.


Q2:
What AFR would you target for low map / decel and why?
Stock is 14.3 on the Open loop AFR Target. I'm currently at 14.7
DFCO is currently switched off.


TIA
Mitch

[steveo]

I've got a log here , rpm's stable within 30 revs. map increases from 62 to 86 in 6 logs.
The AFR Target moves around.
OK I can understand interpolated data .
open loop AFR target at 85 map is 13.0:1
90 map is 13.0:1

so why does the target at 86 map expect 13.1 ??
.... still wading through logs.


there are all sorts of interpolated factors as well as rounding of low resolution (8 bit) factors. it's possible you're putting 13.06 into one end of it, and 13.0 comes out in the table but 13.1 in the log. i wouldn't concern yourself too much with such things, target the ballpark then fine tune for results


What AFR would you target for low map / decel and why?
Stock is 14.3 on the Open loop AFR Target. I'm currently at 14.7
DFCO is currently switched off.

you want smooth.

i wouldn't target an AFR rather than by feel. add some fuel, and if it doesn't like it, subtract instead.

factors are cam overlap as well as exhaust velocity.

AFR measurements during decel can be bunk too so don't trust any wideband numbers <30kpa or so, there's usually a lot of hairy stuff going on at that point

big giant open exhaust often wants to be leaned out a bit more in my experience. fueling errors are easy to tune out in decel since you can hear popping if you're way off (which can be either way too lean, ie lean pop, or way too rich, ie fuel continues burning in the pipe) and you also feel way too sharp of engine braking if you're too lean.

sometimes extreme fuel adjustments are required for decel, but don't be afraid, an engine in a state of very high vacuum doesn't really mind whatever you throw at it.