7747: DFCO without a VSS

[Dr_Grip]

Hi guys,
I am running a 7747-based TBI conversion on my Ford 400. After wondering why DFCO does not work, I saw that it's only activated above 15mph. Problem is: I don't have a VSS.

Can I simply set the DFCO minimum speed to 0mph or will this mess with idle or something else?

Any help, as always, is appreciated.

[Six_Shooter]

This is one of the important reasons to have a VSS. ;)

While I haven't tried to use DFCO on a Delco system without VSS, I have noticed that when playing with it (DFCO) that if the MPH thresholds were set too low it was easy for the engine to stall when coming to a stop. Increasing the RPM thresholds helped correct this, but then the DFCO is active for less time than it would normally be...

So my recomendation is add a VSS, and enjoy the benefits of having a VSS input for DFCO, and other speed based improvements, such as a more stable idle and return to idle.

[Dr_Grip]

This is one of the important reasons to have a VSS. ;)

While I haven't tried to use DFCO on a Delco system without VSS, I have noticed that when playing with it (DFCO) that if the MPH thresholds were set too low it was easy for the engine to stall when coming to a stop. Increasing the RPM thresholds helped correct this, but then the DFCO is active for less time than it would normally be...

So my recomendation is add a VSS, and enjoy the benefits of having a VSS input for DFCO, and other speed based improvements, such as a more stable idle and return to idle.

Thank you for your help! Will do!

Do you have a part-# for a matching VSS (Ford plug-in mount)? Ideally, I'd order all parts needed from RockAuto or Summit Racing, not both, cause shipping to Germany is easily $30 and more...

[84Elky]

As Six said, VSS definitely needed for proper operation. Many idle/not idle decisions that affect performance are made in the code based on VSS data. Sorry, don't have part #.

[Dr_Grip]

As Six said, VSS definitely needed for proper operation. Many idle/not idle decisions that affect performance are made in the code based on VSS data. Sorry, don't have part #.

I think I'll need this adaptor: http://www.summitracing.com/int/part...0006/overview/
And this VSS: http://www.summitracing.com/int/part...0115/overview/
Sadly, I haven't found a matching speedo cable at Summit. The only thing that looks the part is #6800 from these guys: http://www.partshp.com/speedometer_gears.htm

Which means double shipping costs, aka sucks.