patanga

The throttle on my S2 has suddenly decided to lock on under acceleration. It usually comes good but obviously something is not right. The best I can describe it is that it gets to a point under acceleration where it feels like the pedal cams over and then locks on. Any advice on what this might be and how to overcome??

Jfrahm

Have you cleaned the throttle body? Are the throttle body water lines in place?

peanut

has the car been jacked up in a garage recently ?

Its quite common for garages to put the jacking pads under the front floors which frequently distorts the floor and often jams the throttle pedal.

patanga

Thanks 'peanut'. That doesn't sound good. It had new tyres fitted recently.. How can I tell if what you suggest is what happened? And if so, what is the fix?

peanut

mmmthat sounds like it is the floor.
If you operate the throttle pedal by hand with the engine off ,you should be able to detect any friction or resistance . You might have to temporarily disconnect the throttle cable from the inlet.

the answer is to carefully bash the floor down again until the gas pedal no longer sticks anywhere in its travel. Use a lump of 4"x2" and a heavy hammer . You'll have to remove the carpet of course.
good luck

patanga

Thanks again 'peanut' Your advice is much appreciated. I'm sure it must be the floor but what bugs me is that I saw the car being jacked up and it was lifted on the centre jacking posts and then lowered on to car stands on the front posts. All in all I can't fault the way the car was raised??.. I'm sure now that what you suggest is the case so I will do some careful metal massaging to see if it can be bumped back in to shape. Cheers

ZR8ED

Get your face down in the foot well first, and actuate the pedal by hand and watch and feel the pedal movement first if it is binding at the pedal, you should be able to detect it and then make the planned repairs.
Remember the saying of "inspect Thrice, and hammer once"..or something like that! Goodluck!

peanut

If you are convinced that the car was jacked properly then you'll definitely need to disconnect the throttle cable and then check
a, the throttle cable isn't binding
b the gas pedal isn't binding/sticking
c the actual throttle isn't sticking /binding
You might need to lubricate the cable and throttle etc and re-route the cable so there is no sharp bends

Jfrahm

You can operate the throttle at the throttle body end as well, and check it for crud buildup. If someone has eliminated the water lines it could also be icing up.

peanut

errrr....... I've just said that twice already frahm .... keep up lad

what do you mean by the 'water lines ' ?

Jfrahm

Yes and I suggested it in the first reply to the OP (so keep up) but I do not see that it has been done.

The water lines are lines with water in them that run to and from the throttle body. These lines circulate coolant to prevent venturi icing. The condition could be common in the UK this time of year.

http://en.wikipedia.org/wiki/Carburetor_icing

Some people bypass this system thinking it affects performance. I doubt the effect could be measured in real-world performance.

-Joel.

peanut

Ah ........you were referring to the coolant system If it ever got cold enough for the throttle to ice up then i would think that would be the least of your problems frankly.

Hopefully with all our suggestions he should have it fixed in no time

Jfrahm

No, the issue is that the throttle can ice under conditions where you might just see fog or cold mist but no ice on the roads. It is a common enough problem for motorcycles in the UK and I imagine cars as well. The pressure change in the venturi causes a temp drop and can freeze the moisture in the air even if the ambient temperature is not below freezing. I do not know why the 944S2 and 968 got a heated throttle body in particular, perhaps the sporty cold air intake worked too well in this regard.

I think the UK climate is particularly suited to causing carb icing, and for taking ages to dry out my boots.
-Joel.

Fara

FYI: The front "posts" (or circles in the floor) are almost entirely unsupported. It's much better to support the car from the frame rail at the front.

The "post" you are referring to was used at the factory to move around the empty chassis on the automated system and was, as far as I know, never used when moving the assembled vehicle.

patanga

Thanks again guys. The problem is not icing that's for sure. We are currently experiencing temps circa 35 deg C here in Aus. Interesting that you say the front posts were only used by the factory to move the body shells around Fara. When I looked I thought the posts looked a bit light on in floor support at that point. I will do as you have all suggested regards cable and pedal checking first prior to applying any persuasion and report back with the outcome. Cheers