Throttle sticking to the floor!

[heptagon]

The Sigma gave me a fright today, had my foot on the floor overtaking up a big hill on a dual carriageway. Lifted off after the overtake and the throttle remained nailed to the floor. Luckily the road ahead was clear and I was not coming up behind anything else. I tucked my foot under the pedal and it lifted.  I guess I'm looking for sticky action at the pedal or other end of the cable but the fact that the throttle can stick open in any circumstance is frightening.

[Jonathan Kay]

Any recent work on it?

"I guess I'm looking for sticky action at the pedal or other end of the cable"

I'd disconnect in as many places as possible, and then feel the action of each component when worked by hand.

Weren't there some reports of jamming caused by overtightening at throttle bodies?

Jonathan

[heptagon]

Nothing has been done for a long time.  I was out in torrential rain yesterday and did wonder if water ingress could be involved at all.

[SM25T]

Butterfly sticking was with plastic throttle body and overtightened air filter clamp. More likely is sticking pedal pivot. Remove pedal box cover and lubricate it.

[Dixa1225]

What year is your Sigma & does it have a single throttle body? I have had this problem on both my late sigma engined cars.

[heptagon]

It's a 2018 ex-Academy Sigma, same as yours if I recall

BTW that half hood is great, throughly tested it yesterday and it was super easy to set-up, very happy with it :-)

[Dixa1225]

Thought is was an academy car .Send me a PM & I will send some pictures what to check :) Common problem on the later cars.  

[Dave Hardcastle]

In my previous Caterham, the throttle pedal used to 'gum up' around its pivot, over the winter hibernation. I dismantled, cleaned and greased and it happened again the following year.

I then ground some small grooves around the pin to help grease retention. Sold it before I found out whether that cured the problem more permanently. IIRC, it's not practical to install a grease nipple, but I may be wrong.

[Tom_Arundel]

In my experience the problem is that the 2 throttle pot. screws are too tight by about a quarter of a turn which causes the spindle to lock at full throttle......crack them off a bit and give it a try. The TPS should have sandwich plates either side of it but some do not!

[andy_harries]

I have a 2016 ex Academy car and had the same issue with the throttle sticking when the pedal was flat to the floor.  My problem was the pivot on the throttle body sticking.  1/8 turn loosen on the screw and some WD40 to lubricate sorted it.

[heptagon]

Hi all, thanks for the advice.  I had the pedal apart at the weekend so hopefully all fixed at that end.  On the throttle, can someone send a photo of what I should be looking at on the throttle body?  Much appreciated 

[Tom_Arundel]

1. Fully open throttle by hand (mind your fingers!) Does it tend to stick open as you release it?

2. If it does, try easing off these 2 cap screws by a small amount (it helps to shorten the Alan key a bit) don`t go more than a sixth of a turn ( ACW 1 Alan key flat) as you could move the TPS and that would not be good!

3. If the throttle was stuck open, did it release when you eased the screws off?

4. try throttle for smooth open / close with with no sticking (by hand)

 

[Phil G]

#9 agreed.

Happened to me twice in the early days of Superlight Twenty ownership. I believe the throttle butterfly washer/spacer arrangement can cause it to stick open.....very alarming! 

[heptagon]

Many thanks Tom, I'll take a look at this 

[krisfl]

This just happened to me on a windy B road today. Scared the you know what out of me  Had to dip the clutch and brake, the engine bounced of the rev limiter for a second then the pedal sprang back up. It was fine for the rest of the journey.

Will check the points mentioned above this evening.

[7 wonders of the world]

I'd like to think CC would share a workshop technical notice with members for this considering the implications.