Hi there -
I have read about modifying the wiring to the turbo boot sensor to increase boost at idle; which will give better dead stop acceleration: Poor Acceleration from a stop / DDEC I II III IV / smoke control / Fix ?? (http://www.busconversions.com/bbs/index.php?topic=1169.0;wap2)
Has anyone by chance done this to their rig? Does the boost sensor have easy access? Feedback on trying it? Thank you -Nick
That information up on another Foreforums thread just a month ago but the link was to a Busnut page: Fast idle? (http://www.foreforums.com/index.php?topic=30507.msg264471#msg264471)
It seems like a low risk to damaging the engine.
I haven't tried it. The sensor is fairly easy to get to. It's right under the 45 degree rubber boot that connects to the air intake on the turbo (which I had off recently). The sensor is mounted on a plate with a short hose between it and the manifold that is right below the turbo. Three wires like they said.
The connector to the sensor looks like these but I'm not sure: Amazon.com: ACCEL DFI 74813 Weatherproof Electrical 3 Pin Connector: Automotive (http://www.amazon.com/ACCEL-74813-Weatherproof-Electrical-Connector/dp/B001HQHGVM/ref=sr_1_2?ie=UTF8&qid=1492009743&sr=8-2&keywords=ACCEL+weatherproof+connector)
A clean way of doing it would be to make a "male-female" jumper with the resistor added in. Easy to swap out. And easy to go back to OEM.
It's on my summer list of things to do. Here is the link again: BNO BBS - BNO's Bulletin Board System: DDEC - engine slow accelleration (http://www.busnut.com/bbs/messages/233/14052.html?1152765043)
It's not the perfect solution for having a four speed Allison but should help and not harm anything. Once the coach is in second gear direct, it's a rocket but by that time, the six speed Cummins and CATs are long gone.
Will post with photos when I do it.
Pierce
Why fool the computer by giving it false signals? Doing that probably hinders other operations and diagnostic functions.
No, it only tricks the ECU into thinking it has 2 psi boost when it has none and is just used to add fuel momentarily to cross an intersection. This is called "smoke control" on the later DDEC versions and can be switched off. Once the intersection is crossed and the boost comes up normally, it has no function.
This is accomplished with a switchable fixed resistor with or without a variable resistor. Depends on the amount of fuel you want to add. Marine ECU add a lot from the start.
Pierce
My coach had a similar problem. An in-frame engine overhaul fixed that. Cost a bit more and took a bit more time, though. ;)
I had a metro bus with a 6v92 DDECIII or IV. I'm familar with the (dis)function :) For the day, loved the 2stoke. But I love my cummins in my RV and boat now. Still have a 4-53 in an old dumptruck. Always starts right up!