D1 STEPPER MOTOR ON A D2 MANIFOLD

[miles]

First off I would like to say thanks to BLKnight.au for his info on the 14cux
and especially his referals.

I read the artical by BritishV8.

This now begs me to ask the question, when installing a Thor manifold onto a 3.9 D1 engine and using the D1 fuel injection system 14cux. when connecting the 14cux stepper motor & housing to the thor manifold, PhilipA suggested to connect the main vacuum hose to the brass vac take off spiggot on top of the manifold.

However the article by BritishV8 on " Service and troubleshoot 14CUX Electronic Fuel Injection says the Bypass Air Valve vac hose should be connected to the plenum before the throttle body.

In PhilipA's advice to me, he said he used the vac spiggot on the bottom of the Thor manifold throttle body to hook up the rocker cover breather hose.

The question is, is it imperitive that the Bypass Air Valve (stepper motor)
be connected before the throttle body?

I run a Haltech E6 Engine management and not the 14CUX unit. The distributor is modified for the Haltech, no MAFE, other than that the system uses the same components as the 14CUX.

Incidently I also use a Haltech Stepper motor, a standard stepper can be used, but mine stuffed up so on advice from my engine tuner I fitted a Haltech Stepper motor ( that was 2 years ago and still functioning well)

[bee utey]

When installing a Thor manifold onto a 3.9 D1 engine and using the D1 fuel injection system 14cux. when connecting the 14cux stepper motor & housing to the thor manifold, PhilipA suggested to connect the main vacuum hose to the brass vac take off spiggot on top of the manifold.

However the article by BritishV8 on " Service and troubleshoot 14CUX Electronic Fuel Injection says the Bypass Air Valve vac hose should be connected to the plenum before the throttle body.


The stepper on a D2 takes air from the intake hose before the throttle body and drops it in the 1 inch port on top of the manifold. If you are running LPG the intake of the stepper must be connected between the throttle and the mixer. Otherwise it needs to be connected between the throttle and the MAF. I believe the British article refers to the port on the side of the plenum/throttle that is part of the standard D1 manifold. This opens into the intake just before the throttle plate.
The pic shows a standard D2 with a LPG mixer and MAF installed using VN Commy air intake hoses. The original D2 hose has a spigot for the stepper intake, I used the elbow section only.

[miles]

Thank you Bee Uty. This is exactly what I thought.

I have made up a plate for the 3.9 stepper motor housing (where it bolts onto the D1 plenum) and corresponding to the open square hole I will fabricated a 1" spigot and plumb it into the 1" branch on top of the Thor.
A job for tomorrow.