I finally got some big injectors in the TBI, put the pressure at 20 and then set the BPW to (now) 68

spent the day tuning it with the WB, things seem to be going well except that Ive run across a strange leanness as i let off the throttle and come up on alot of vacuum the car instantly goes down to like 17-20:1 afr and spits and gurgles like hell, this seems to be between 1600 and 2000, the fuel cells there im pretty sure are close, if not rich, 30 kpa is where i cruise at and ive set the 20 kpa row very close to what 30kpa is at.

Ive made sure the DFCO is disabled by rasing the threshold rpm to the highest value and lowered the threshold maps to 0 etc, basically made every setting so that no matter what its not coming on.

What gives?

 

btw with the small injectors and 112 bpw the car did not do this.

 

It also does decel enlean in addition to DFCO when you get off the gas.

 

Also, how much SA do you have at low map and mid rpms? I boosted it up untill it was almost the same ammount that I have during cruise and all the noise in teh exaust goes away since it now has enough timing to burn off the fuel.

 

ah, decel enlean.. im not familiar with that one im gonna go look into it.

As for the spark table, im trying to leave that alone for now atleast because with the carb on there the spark table worked great.

 

ok i found it in the hack

; DECEL ENLEAN PARAMS
;
;----------------------------------------------
LD2E0 FCB 3 ; 1% TPS DECEL ENLEAN INCR THRESH
LD2E1: FCB 8 ; 2.5 Kpa DECEL ENLEAN INCR THRESH
LD2E2: FCB 96 ; 0.375 ENLEAN MAP FACTOR
; (Mult 0.375 * map for calc)



There also seems to be alot of talk of closed loop with decel enleanment in the hack, almost seems like its only active in closed loop from what Ive read. Im running open loop but it still seems like decel enlean is exactly what im experiencing as im easing up on the throttle. How would you go about disabling decel enlean entirely on the 7747?

 

Decel enleanment (DE) is in effect with both open & closed loop. It's purpose is to compensate for the evaporation of fuel from the intake manifold walls as the MAP drops. Something to be tweaked but not eliminated. To eliminate it set the delta TPS% at LD2E0 to 255.

Most likely the issue at hand is the transition from sync injection to async injection. Once going to async the AFR is leaning out.

Set the async2sync and sync2async parameters to zero and try it out:

RBob.

 

hmm, that didnt seem to do it