TroyN

I've searched several boards and also the Bentley but can't find a) what the correct setting of the cable is, i.e. how much slack, how to tell what is fully open, etc. or b) how to adjust it if it's off. My cable has about 1/8" of slack and with the pedal to the floor, the stop on the throttle body is not contacted. Anyone know? Thanks much.

Macster

I too searched my references and found nothing.

I've never adjusted throttle cable on the Boxster, but I have for a few other cars and motorcycles and lawnmowers.

Basically there wants to be enough slack that with the butterfly valve can rest on the throttle closed stop. The valve should not close completely cause it can get stuck in the throttle bore. Usually there is a small gap. The butterfly return spring or cable return spring (or both if the car has both) must be present and functioning. It is generally not a good idea to substitute a larger/stronger or weaker spring.

IOWs, the cable does not want to be so tight that the butterfly valve can't close all the way cause the pedal (for instance) is against its fully released stop and this holds the butterfly valve open slightly.

As for the fully open part, this is verified -- with engine off -- by having someone press on the accelerator pedal fully until the pedal contacts its stop (there can be one under the pedal on the floorboard) and someone outside the car at the throttle verifies the valve is fully open. If the valve is not fully open the pedal stop needs to be adjusted or if there is a full throttle stop at the throttle this needs to be adjusted. Note fully open may not mean the butterfly valve is completely horizontal. There may be a built in stop that prevents the valve from opening this far. Don't worry, this will not affect top end speed.

Be sure you clean the area under/around the pedal and clean and properly lubricate the pedal pivot -- unless this pivot is sealed -- so the pedal's action is smooth and non-binding. With the cable disconnected at the pedal the pedal action should be smooth and even.

You can disconnect the cable from the bell-crank and work the cable by hand to verify the cable moves in its sheath with no binding or excessive drag/friction. There may be a cruise control module around someplace too which may have to be disconnected.

And at the throttle body with the cable disconnected the work the butterfly bellcrank by hand and verify the butterfly valve action is smooth.

I do not know if the cable requires periodic lubrication.

Needless to say there's no room for messing with this if you're not comfortable with it. Engine throttle cables play a vital role in the safe operation of the vehicle so best to have a professional adjust this and give the system a check out, especially absent service manuals on this item.

Before you start take good pics of everything and note you can see in the pics what the adjustments are for the various stops and such.

Note how the cable is routed and any wiring and such to/from the throttle body and cruise control module.

If you have any doubts about your ability to make the adjustment properly -- and my info above is not intended to replace the proper factory instructions -- and safely take the car to a professional.

Sincerely,

Macster.

TroyN

Good stuff Macster, I appreciate the thoughtful and thorough response. Do you have any idea whether there is a "full throttle/wide-open throttle" switch, or is that just built into the TPS somewhere in the range it would consider WOT?

Macster

Sorry, but no, I do not know if there is a full throttle/wide open throttle switch. I've never been at a pre-e-Gas Boxster engine and do not know what sensor(s) Porsche uses along with the cable operated throttle.

Sincerely,

Macster.