Has anybody played around with the proms proportional gains for the 747 @ 0x4A8. I'm experiencing surging at steady loads at 2500 and over. Just wondering If anyone has had sucsess changing gains.


Form DIY-EFI.ORG

"PROPORTIONAL ERROR TERM:

Once the slow filtered error term is calculated, it is used as a
lookup index into the proportional gain table at: 0x4A8.

Another lookup is done for a proportional multiplier term, indexed
by airflow in gms/sec, at: 0x4C7.

The two above terms are multiplied together, divided by 256 and
the result is used as the adjustment to the CLT term.

The math:

PropTerm = (Gain @ 0x4A8[O2err] * FlowGain @ 0x4C7[gms/sec]) / 256.


This makes the FlowGain (@ 0x4C7), dictate a percentage of the gain
table (@ 0x4A8). The end result will always be lower then the starting
gain term.

To create the CLT, the proportional term is either subtracted, or added
to the INT term. If the O2 sensor is lean, the prop term is added to the
INT. If the O2 sensor is rich, the prop term is subtracted from the INT
term. The result is the CLT term.

The CLT term is then used to adjust the BPW calculation.


For highly tuned engines (IE: hot street stuff), the proportional
gains can to too high. The effect is the engine surging under steady
state cruising. Reducing the gain and multiplier values can reduce
this problem. The values in these tables can sometimes be cut in half."

 

well hook up a vacum guage and watch the o2 swing. if it looks out of wack start at 25%. if it settles down and needs a bit more tweaking go another 10% then just toy with it till its perfect. you get the picture. you already answered yr question.