Need help (fuel??). vortec-tbi 7747
#1
Need help (fuel??). vortec-tbi 7747
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).
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).
Last edited by helo; 01-20-2011 at 11:36 AM.
#3
Re: Need help (fuel??). vortec-tbi 7747
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
#4
Re: Need help (fuel??). vortec-tbi 7747
What is plugged return?
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)
Last edited by helo; 01-20-2011 at 02:35 PM.
#5
Re: Need help (fuel??). vortec-tbi 7747
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.
#6
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Car: check
Engine: check
Transmission: check
Re: Need help (fuel??). vortec-tbi 7747
Note that the TBI body to adapter fitting threads are 12mm X 1.25
RBob.
#7
Re: Need help (fuel??). vortec-tbi 7747
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*).
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*).
Last edited by helo; 01-21-2011 at 02:20 PM.
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Car: check
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Transmission: check
Re: Need help (fuel??). vortec-tbi 7747
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*).
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*).
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.
#10
Re: Need help (fuel??). vortec-tbi 7747
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.
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.
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