One symptom is a noise, when you turn the engine off, you normally hear a whistle from the front of the engine, this whistle or whine goes on for around twenty seconds, if you no longer hear the noise, or hear a grating sound, pound to a penny it's the Throttle Box seized or stripping the gears.

Hi ad210358,

Thank you for the reply.
Any sympton while we are driving the car? Lack of power,Alarm message,for example?

Comments anybody on the following thoughts
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1/. What real function does the throttle body do? There is mention of people having the gears mashed yet still driving. So if one stripped the mashed quadrant gear out and set the butterfly for straight through what faults would engine exhibit?
2/. What makers names are seen on these units ? Could we contact the manufacturer and do a group buy of say 50 plastic quadrant gears?
3/. If the throttle body is clogged with exhaust EGR droppings what's the condition of the 4 inlet flaps? Surely they are ready to bust as well?
5/. Has anybody tried setting the inlet 4 flaps at straight through and blanked off the vacuum servo actuator?
6/. I've fitted an EGR blank to my MY2010; has anybody else done it permanent?
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I hope I generate some comments....
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Kind regards from Fred.
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Fred

Not sure about any of your questions except a comment about number 1.

I am sure I have read somewhere that the function of the throttle body on the FL is to aid shut down of the engine when it is switched off by cutting the air supply - it helps to stop run on or in the worst case scenario the engine running on its own oil if the engine is worn or faulty.

I remember on my previous FL it used to make the noise when I first bought it, but realised towards the end of the time I had it that it didn't do the shut down noises that it characteristically makes when functioning properly, and it then also tended to chug a bit and stop with roughly when switched off. I suspect it had failed but didn't make the screeching noises that some have. On my second FL, as soon as I bought it, I realised the noise was there on shut down (whistling/flapping noise) and the engine switched off very smoothly.

I wonder now if on my first FL it failed quietly and perhaps the default is to fail open, so normal operation of the engine is maintained except for when it is shut down.

I may be completely wrong. Just my thoughts.

Andrew 2016 BMW X3 30d SE in red
MY2013 SD4 XS Firenze Red, 19" 10 spoke contrast paint wheels, Signature Strips, Grand Black Lacquer trim, Cold Climate Pack - gone!
2007 TD4 S Stornoway Grey - gone!

Just joined the failed throttle body club. lasted 140k miles though.
When I took the failed unit apart - doesn't everybody? there were two stripped sections, the flap would not have fully opened as the last third of the quadrant gear was badly worn, wonder if this has been the source of the worsening fuel economy? On a long run (say 400 miles) I would have hoped to get 33-34mpg, but was only getting 30mpg, bearing in mind great chunks of the M6 are 50mph zones

The second section that was stripped was in the flap closed position, this jammed and stopped the engine from starting.

The air path was actually very clean considering the mileage, no carbon lumps, no gummed varnish (is that only petrol engines?), the flap was very free to move once the large gear was removed, so no jamming of the flap.

Crossed fingers if the throttle body is relatively clean, then the stupid manifold flaps might be in good order.
Remember though that I do 40miles each way to work, mostly motorways, and I don't have the "environment saving" Stop/Start function, which has got to be easier on the car.

Thanks for the links to the manual, didn't half make the job easier. Tangiers Orange - gone, missing her
Replaced by Ewok what a mistake - now a happy Disco Sport owner

Andy, with you having stripped the throttle body mechanics and looked at the damage ; what is your educated opinion as to the cause of the gear stripping? Is it just old age?
I was wondering if you would reccomend taking the cover off periodically for a clean and regrease?
.
Kind regards from Fred
. 2010GS Auto ex Celeb, Santorini Black, 2011 facelift , spoiler, spats, mudflaps, LED footwell lamps, Witter detach,
Other cars:-
1958 & 1959 Austin J40 Pedal Cars under restoration (I make many J40 parts)
If you have an Austin J40 or Pathfinder Pedal Car looking for a new home pls PM me.
2009 Meriva

There was some oil inside the gear case, not enough to wet things through, but enough that the gears were living in an oily atmosphere - my guess is that the throttle bod9y gets quite warm, so more like an oily sauna.

The center section of the quadrant gear had wear, but it would have carried on for as long again.

That both ends have worn/stripped might imply that the unit was overtravelling.

There is a carbon track that gives feedback to the ECU about the flaps position, if this track was worn/contaminated I wonder would the flap be driven hard against the mechanical stops, stressing the plastic gears?

Then again I could be barking up the wrong tree, maybe it spends most of its life at either end. It might be either fully open and running, or fully closed and stopped.

Definately nothing seized, stiff, or showing signs of friction (apart from the severed teeth) in my case, so I will not be stripping down periodically. Tangiers Orange - gone, missing her
Replaced by Ewok what a mistake - now a happy Disco Sport owner

Just a thought

If you take out the intermediate gear, the flap will remain fully openbecause of the spring, the car will start and run as normal.
OK it might close down with a judder, older cars do this, in some cases for hundreds of thousands of miles without harm.

The ECU will log a fault, but it will not put the engine management light on - as it doesn't effect emmission?
So where is the down side, car runs as normal, MOT not at risk because of engine management light, and one less thing to cause a breakdown? Tangiers Orange - gone, missing her
Replaced by Ewok what a mistake - now a happy Disco Sport owner

I had this a couple of years ago on a 10 reg with about 35k miles. I had the chewed up gears and the car was only just about driveable (kept stalling). A LR service manager told me that if your throttle body is playing up then remove the electrical connector, you will get an engine management light on but it will get you home.

He also recommended undoing a torx screw on the top and squirting some brake cleaner in occasionally to clear the crap out but I have never tried it.

It does seem odd that we rely on plastic gears on an item like this, the return spring is rather strong and I am surprised that the unit works at all. But perhaps that's just my jaundiced view of this well designed but rather under engineered car (ie I think I have yet another wheel bearing going) 3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE