I have a severe hesitation if I give it more than a touch of throttle off idle. It will not idle or run with MAP unplugged, so I'm pretty sure the tune needs adjustment.

Is off-idle open-throttle around 60-100kpa??? Or what?

What's Min/Max BLM for? Will lowering the min allow the ECU to do more correction as needed?

I can burn chips, but I'm not sure exactly what I need to adjust in my prom. No idea what controls the ECU's behavior with MAP unplugged...

Comparing to brdw/63.zip, my VE table appears close with adder table considered.... I know datalogging will help, but will fuel issues do this? It also backfires out TB during the hesitation.


5.7 Vortec-TBI ('96 suburban engine, GMPP intake). 7747. Stock 350 injectors, external AFPR set @18psi with 60psi pump, blockoff plate and plugged return at TB. Mostly new sensors/parts (TPS is old, but ok).

I can't datalog yet, so don't flame me on that... (I think it's my 2ghz dell laticrap's UART, tried 1 transistor and a max233).

What is plugged return?

has anyone ever bought somthing from someone from here? and how do you go about paying and reciving it and how you know your not gonna get screwed

12mmx1.5 bolt with teflon tape in the return line passage =). My external regulator is mounted back by the tank, only 1 line to the TB for right now.

I just tried increasing values in the adder table (43 instead of 39) and decreasing min BLM (98 instead of 108), and the hesitation wasn't as severe.

I once read somewhere it's bad to run with VE of 100? Should I increase my FP more, or is ok to run with high VE's? (BRDW has some values of 96-99)

Backfire out the intake is lean mixture OR spark crossing over OR intake valves not sealing OR exhaust valves not opening. You have a lot to check out. I have the same setup in my Jeep and I couldn't be happier with the combo. I would start with a 5.7 tbi bin and change NOTHING until it works, only after that you can start tuning. Just my .002 worth.

You have to run a return line from the TBI. Can't go return less, doing so causes too many problems.

Note that the TBI body to adapter fitting threads are 12mm X 1.25

RBob.

Thanks, I'll try higher fuel psi. I'm 99% sure it's just a lean problem, not mechanical.

I think I might run a vacuum line to my aeromotive, too, instead of leaving it open.

I talked to a GM tech who suggested maybe I have no serial data because my SES bulb is out (I can read codes with test light on ECM harness.. *grin*).

You need SES-CE light to confirm chip is healthy. key on-engine off you should be "blinK" then steady on to validate chip you just modified. A rapid blink is bad chip. No light is bulb or bad ECU.

Shouldn't run a vacuum line to the FPR unless the ECM has firmware to go with it.

The '7747 will still xmit ALDL without the SES light. It is the older ECMs (CCC mostly) that require a working lamp driver module and SES light to xmit on the ALDL line.

RBob.

I should have been more concerned about the SES bulb. PO removed the bulb socket, ECM was bad. I feel like kicking myself now...

Thank you for all the good advice. I'm getting data now with a junkyard ECM I picked up this morning; now the fun can begin.