Technical Forums > Fuel Injection

Modified Accelerator Cable

(1/17) > >>

tmsmini:
My swap to a 45mm SC throttle body continues to annoy me. This is not really an injection issue as even some HIF carbs need some special treatment for throttle cabling.

I have made a number of other changes along the way just to complicate things, but it all did work previously. I was trying to fix things that were marginally "broken."

This issue really has nothing to do with the throttle body as far as I can tell. It is an accelerator cable issue, maybe a cable alignment issue.

SC originally suggested using the MPi cable as they thought because I was using an MPi engine I must have an MPi. It is totally inappropriate and I abandoned it before we went to Oregon two years ago, too long, hits the bonnet and both ends of the cable are terminated.

I am using one of their cables which is supplied by the people who make their throttle bodies, AT Power(https://www.atpower.com/). It worked fine for the 50 MM TB.

I have to be making a simple mistake. I never liked having the adjustable ferrule on the pedal end of the cable, but that is what they supply. I added a couple of Venhill(thanks for the tip) cable ends to make the curves as smooth as possible. I trimmed the cable as short as possible, making sure not to hit the bonnet and still have a smooth radius. I have tried several cable lengths. I added some shrink tubing to the cut cable ends to make sure they centered properly in the metal cable ends.

In this movie you can see that the mechanism sticks, yet the cable is not sticky and falls from the weight of the pedal when free. With no cable, the throttle returns to 0 all the time.

https://www.youtube.com/playlist?list=PLNWUxao2Iq7HsRWOL_yeIzjEL5G-26Bpo

The problem seems to be worse on the road. In the driveway, it will not stick all the time. On a drive, it will stick at the first stop sign. Give it a rev and it returns to 0 most of the time. Sometimes one or two strong revs are required to get it back to 0. I thought it was heat related, but I cannot confirm that.

A friend suggested I shorten the threaded portion of the Venhill cable end on the TB bracket to give the cable a longer untethered run to the throttle quadrant., which I have done. It seems to have improved things a bit.

But any other ideas are welcome.
It seems the slight dimensional changes of the inlet manifold and the throttle body have had some consequences I did not foresee...

LarryLebel:
Is there a throttle position sensor that is sticking?

tmsmini:
I thought that might be the case. I swapped sensors with no change and this is a new throttle body with a new TPS and the issue remains.

MiniDave:
Add an additional throttle return spring? Not heavy, but just enough to overcome whatever is causing the hangup? Could it be simple friction inside that radius tube?

tmsmini:
I am looking at an extra spring. The later cars had one on the pedal. I am looking to see if the MK I pedal box will make this easy.

The cable slips easily when loose from the quadrant and falls from the weight of the pedal. I think I tweaked the cable bracket on the 50 mm TB to make a smoother transition, but with the position of the fuel rail and the revised filter location, there is no room to change anything.

Navigation

[0] Message Index

[#] Next page

Go to full version