Technical Sticky throttle

[Velocemitch]

Daughter had the rather interesting issue of a throttle sticking wide open on the Selecta the other day. She has dared drive it since, so I'd better take a look.
Any ideas what this could be?, it seemed to fix itself for no apparent reason.

 

[Velocemitch]

Re: Sticky throttle (Selecta)

MMmmm
Just been out for a run around and its not very nice this... !. What seems to happen is if you rev the car hard it changes down as it should but when you lift off its holding the power on at the same revs as it was when you lift off.
There appears to be a second throttle cable coming out of the gearbox unit, which I think is causing the issue, I presume the Selecta system has something to adjust the throttle automatically during gear changes and I think its that bit that is sticking.

Its a bit disconcerting as it wont let you knock it out of gear either.....

 

[Sjvarley]

Ok try putting your toe under the pedal to pull it back it could be stuck or frayed within the outer cable try Wd 40 down the outer if you can had this on a auto before

 

[Velocemitch]

No it's not that simple, the throttle pedal does come back up, I think it's the second cable into the gearbox which is holding the throttle open. All the cables look in good order.

 

[Sjvarley]

Ok get the car off the ground one wheel will do handbrake on. All other wheels blocked out in all directions take off front wheel the side which is away from the box now try ithrough the gears on tick over using throttle by hand with the filter removed see the results then rectify. DO THI S ONLY If Your Very confident about the situation this will allow observation of the cables also movement.

 

[Velocemitch]

That sound interesting. What am I looking for?.
I haven't researched this much yet, but I'm guessing there is some sort of sensor in the box which is monitoring the throttle position and decides if it should kick down a gear?.
Or does it actually alter the throttle setting from the box somehow?.

I'd need to be pretty confident the diff won't lock to do what you suggest?.

 

[Sjvarley]

Ok if your not sure lift both wheels off the ground and remove but keep well clear of rotating parts !!!!!!'
It's like a scooter drive 2 pulleys and a belt that work on centrifugal force one gets smaller one gets bigger changing gear then a electric clutch that engages and disengaged

 

[Sjvarley]

Forgot to ask how many miles has it done ?? These type of boxes don't last much more than 65 k Sorry

 

[Velocemitch]

Yeah, I know how it works. Not sure how it would behave under that type of test though. The kickdown system works on road speed, throttle position, engine speed, etc etc. Without any load on it the transmission probably wont behave normally anyway.

 

[Sjvarley]

Really to isolate the throttle action from all other inputs 1st to determine if it is a box or throttle problem as your thread was sticking throttle I know it could be more but 1st things 1st prove it's not the throttle .sj.

 

[Sjvarley]

Really to isolate the throttle action from all other inputs 1st to determine if it is a box or throttle problem as your thread was sticking throttle I know it could be more but 1st things 1st prove it's not the throttle .sj.

As the second exu could be getting not signals it requires to control throttle

 

[Liquid Knight]

I had this with my Fantasia when I first got her.

The rubber cone at the end of the cable has perished and was holding the carb' open.

It also happened on my Cinquecento Sporting.

You can simply pull it off and the car will be fine without it.

Sorry if that has already been covered and addressed but I'm in a hurry and didn't have time to read the whole thread.

 

[panda1408]

I had this with my Fantasia when I first got her.

The rubber cone at the end of the cable has perished and was holding the carb' open.

It also happened on my Cinquecento Sporting.

You can simply pull it off and the car will be fine without it.

Sorry if that has already been covered and addressed but I'm in a hurry and didn't have time to read the whole thread.

I was going to suggest this, but if the pedal is returning as normal I can't see it being the problem. Unfortunately I don't have much experience of the Selecta box to offer any more help. Most Easterly Pandas might be able to though?

 

[Most Easterly Pandas]

Re: Sticky throttle (Selecta)

Forgot to ask how many miles has it done ?? These type of boxes don't last much more than 65 k Sorry

Not so. They tend to die at 15-30k miles or are good for 150k plus from what I've seen and personal experience.

You only tend to hear about failures however

There appears to be a second throttle cable coming out of the gearbox unit, which I think is causing the issue, I presume the Selecta system has something to adjust the throttle automatically during gear changes and I think its that bit that is sticking.

It doesn't. The cable into the gearbox is purely a mechanical kick down for the gearbox when you boot the throttle. From memory the throttle body rotates to pull the cable out of the gearbox when you give it gas, not the other way around. So if the cable is sized it'd either stop throttle from being applied or would go slack and stop the gearbox from operating at optimum performance iirc.

 

[Velocemitch]

The car is low mileage, about 20k so it's not worn much. The rubber cone looked ok, not perished.

So the kick down cable is unlikely to be the issue then, is there any other systems altering the throttle apart from the obvious cable system?.

 

[Liquid Knight]

I was going to suggest this, but if the pedal is returning as normal I can't see it being the problem. Unfortunately I don't have much experience of the Selecta box to offer any more help. Most Easterly Pandas might be able to though?

Pedal spring taking the slack.

The cone is the end of the dust cover at the throttle body or carb' end.

If that's eliminated then you need to manually operate the throttle from the engine bay as it could be something like the bearings in the carb' or body not allowing the butterfly to close. Squirt some motorcycle chain grease in there every couple of years to stop that from happening.

With such low mileage lack of use could make stiffen up.

 

[kolza]

Is the car injected or carved?

 

[Velocemitch]

Car is a very late model on injection.
Just had another look, at the moment problem seems to have gone away, it drove OK despite me prevoking it as much as I could with lots of full throttle work. The kick down is fine, I'm coming to the conclusion it's not really connected to the selecta sytem, which can only be a good thing. Wondering if it's something to do with the stepper motor which I believe controls the throttle at idle. It was very very cold the day it did it, the engine was hot mind, so I'm not sure if those things are connected.

Although it's low mileage, nearly half of the miles have been wracked up in the last 12 months, so it's not lack of use as such.

Totally unconnected I expect, but there is a split in one of the HT leads, which would explain an odd misfire which occasionally surfaces, just off to get a new lead set and some plugs.

 

[panda1408]

Pedal spring taking the slack.

The cone is the end of the dust cover at the throttle body or carb' end.

If that's eliminated then you need to manually operate the throttle from the engine bay as it could be something like the bearings in the carb' or body not allowing the butterfly to close. Squirt some motorcycle chain grease in there every couple of years to stop that from happening.

With such low mileage lack of use could make stiffen up.

No spring on the pedal

 

[kolza]

It is not mechanical fault for sure. Adam had same problem with his parade. intake air pressure or temp sensor was temperamental.