[Diy_efi] Holley projection questions

Simon Juncal sjuncal
Fri Mar 10 06:08:19 UTC 2006

Hello new to the list here. I found some of this lists posts googling my 
pro-jection problems and thought maybe I could find some help and opinions.

I got the digital 1d system used for next to nothing, open loop for now, 
So I've got a bunch of ideas and questions... like has anyone hacked the 
ECU so that the fuel maps can be programmed via laptop?

I notice the closed loop "system" they sell for 200 dollars is just an 
o2 sensor, 3 wire harness and a proprietary connector... has anyone 
patched in their own o2 sensor? Does anyone know which post in the input 
connector accepts signal from the sensor?

I've asked holley tech sup a few basic questions and gotten canned 
replys and multiple copies of the instructions sent to me in PDF :)

The PO of the system had it on a Sazuki Samurai, on which it ran super 
rich... it's now on my Jeep 4.2, (with 4.0 head conversion, original 
intake and 4.0 header) which is the target aplication of the 1d system. 
The PO along with the help of someone at Holley had the TPS wiring 
turned around and spliced in the harness ground, the voltage range is 
3.7 to 4.7 nowhere near the 0.63 holley's instructions recomend. I can't 
explain why, because as near as I can determine this range ENRICHES the 
overall fuel mix (making it harder to lean out via the ECU knobs) and 
makes the fuel curve more drastic.

That said this TPS setting get's me a running, smoothly idling (for a 
jeep) engine but it runs constantly rich, doesn't start easy, gets 10 
MPG (16 to 18 is normal)... SLOWLY leaning it out in the tuning process 
gets me JUST to the Stoich on my autometer gauge, better MPG, hessitant 
acceleration, and inconsistant dropout's where it leans totally out if I 
_barely_ touch the throttle, but riches back up when I get further into 
the pedal. Crusing with foot resting on pedal leads to long off the 
scale lean conditions, and occasionally it leans out at idle, and will 
stall if left alone without pedal.

Problem is just reversing the wiring back to what the instructions show 
doesn't get me any fuel, the ground as I said is spliced in or Y'd to 
the Grey TPS wire both then going to the black harness wire back to the 
ECU... Seems strange to me but I can't find anywhere else in the harness 
that the ground wire might actually have been attached to.

There's only one black wire at the ECU input connector, the TPS has a 
black wire, and this ring terminal ground. are they really supposed to 
be Y's together like that?

Sorry for the long assed post, but I've never been too worried about 
being in over my head. I'm too used to the feeling :)

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