Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGF Technical - Throttle Body Sticking

I know that this has been talked about recently, but I have been told by the dealer that the throttle is sticking and that I need to replace the whole body.

Can any one tell me if there is a benefit in replacing it with the alu one that has been talked about, anyone know what it costs? Does it improve throttle response?


The main advantage is that an ally one would be less prone to warping, but having said that why does your dealer say it needs replacing?

If it is warped then why is it warped has some one replaced the Rover clip with a Jubilee (worm drive) clip and overtightened it?

Do you have a direct fit filter such as the K&N?

The other thing to look for is it warped or is it just 'gunged' up.

Ted Newman

IMO if it does (not saying that it does) need replacing, i am a strong believer in replacing parts with the best available at reasnoble price. The additional part cost will be minimal (maybe even less if it is not a rover part) and the labour costs are the same, if you are paying for the labour you may aswell get the best put in.

The throttle is sticking abit when you lift off the power, a clean would help I expect, what would suggest I use (WD40?).

Also I am told that rover have modified the part because of this problem.

Yes I do have a K&N fitted, but is this likely to effect this.


One of our MGF racing colleagues reported a sticking throttle due to the build up of 'black gunge'. He simply stripped the throttle body down and cleaned it up with petrol. Job done, and better fuel economy to boot!

There has been an association made between the use of jubilee clips (as used with K&N and other air filters) throttle body distortion. In fact, Rover distributed such a warning- so maybe, if your dealership technicians are aware of this official circular, this is the reason why they are suggesting throttle body replacement.

IMO it would be far more sensible to investigate the condition/ cleanliness of the throttle body- stripping and cleaning if necessary (or you could try a proprietry carb cleaner from somewhere like Halfords) - before instigating throttle body replacement. This is all assuming that the problem isn't being caused by throttle cable sticking...

Slightly off thread, the Lotus Elise owners have had problems with a batch of defective throttle bodies- many of which were replaced under Lotus warranty with alloy items.

Alloy vs plastic? I suspect that they both have a similar performance in terms of air flow (although it is interesting to note that the Trophy 160 has an alloy TB), so toss a coin. Or go for the cheaper. Or go for the one you think will last the longer. I don't honestly think that there is much in it, but overall I personally would choose the alloy one.

Rob Bell

If I remember correctly, Roger said a while ago that all K engines used to be made with alloy throttles originally but were later replaced by plastic due to some problems. Now they are going back to alloy!!
Spyros Papageorghiou

correct, but the early bodies had an integral stepper motor so it would not immediately appear to be interchangeable.

For sleaning there are some carb cleaners, sometimes called choke cleaners, which are in aerosol cans. These provide a strong directional spray which is great for cleaning. Initially spray this onto the inside of the throttle body, which will be quite dirty. Then use a cloth to rub the inside which dislodges most of the cr*p. Then use the spray again to 'flush' the resulting sludge out. Dry off as best you can before restarting the engine.

When restarting hold the throttle slightly open as you crank the engine. This will help overcome the flooding effect that this and other solvents will have and allow a rapid clearing of the induction system so that the system can settle down to normality.

If the cleaning fails and you have to replace then bear in mind that the plastic bodies were a while ago being sold off at around 55 and so I have a new spare. I fancy that the new alloy bodies will be well over double this.

Roger Parker

I'm after a more or less cheap aluminum throttle body since I saw one at an Elise from Moto-Concept.

Common is the use of a Opel (Vauxhall, GM) Omega 3.0 l throttle body with app 58mm centre diameter. Hard to find at crap yards, though. It's original at the GM engine C20NE.
Another alternative is R.E.D. Motorsport who sell a special molded and use it at the Elise also.

The last info I got leads to Jenvey / UK. They have loads of different aluminum throttle bodies and also the supplies including a throttle potentiometer.

IMO there will be no power increase without any other modifications, but such a flap will hopefully not stick.

Just the facts only, but no own experience. I collect all that stuff currently at

Dieter Koennecke

just checked my F build date 23/02/01 1.8mpi and it has an alloy throttle body.

VVC ? or 1.8i ?
I suppose all from VIN 1D522572 upwards will have it
Dieter Koennecke

I was amazed at the sticky gunge behind my throttle when I looked last year.
It wasn't sticking tho
1.8i, K&N +3 years
John Thomas


I have had a problem with my 214 - same plastic throttle body - for some time, in that it is very slow to drop the revs on lift off and sits there blipping the throttle by itself when the car is (supposed to be) idling. That is rather annoying. The garage stuck it on Testbook and the potentiometer failed. They advised a new throttle body at 250 plus fitting and VAT, which I declined. I've since had a quote for a potentiometer on its own at around 62 plus vat, so if anyone has a spare I'd be glad to hear about it. I wonder if this could be the cause of some of the incidents of MGF sticking throttles? It's not easy to diagnose without testbook.

Do new throttle bodies come with all the gear installed, that is the butterfly valve, spindle, potentiometer, etc? I'm just wondering where my garage dug up the frightening estimate for a replacement? It must be over 100 an inch of plastic (some type of nylon, I believe).

On another aspect, all you K&Ners, how clean is the inlet tract between the filter and the butterfly valve? I'm just curious about conducting a very crude survey of filtering efficiency.

Regards, Kes.


Contact me offline. I have a spare. A very long story how I got it! :-)

Also, check it's not the cable/contacts first.

Wouldn't bother with a new throttle body. Just clean it as suggested.
The oily gunge doesn't come through the filter, but comes from the recirculated stuff from the charcole
canister for emmisions purposes.
The inside of the KnN should be clean.
Oh... but remember and clean the KnN on the outside. Makes quite a difference. :-)


Paul Nothard

Kess, the inside of my K&N/ TB inlet is always clean- although the filter itself has to be cleaned every 10-12 months because of the build up of debris on the *outside* of the filter...

Rob Bell

Thanks for all the advice, I cleaned it the other night and touch wood it seems to have cleared the problems (loads of black gunge).


Got my car back on Monday and they only charged me 420.
Mark Brunt

Cor! That's better than expected, but jeez.
At least it works now... :-)
You still going next Friday ? I need Jo to sanction the exhaust. <g>
Paul Nothard


Yep will be at the Phoenix if thats what you mean.

Mark Brunt


Thanks Paul, I have mailed you.

For those desperate to know, in 1994 the K-series was the first production car engine to use a plastic throttle body and inlet manifold. The throttle body and throttle valve were made of Du Pont's Nylon 66, while the inlet manifold was made of Zytel, which is Nylon 66 reinforced with 30% glass-fibre. The weight reduction achieved was 53% for the throttle body and 40% for the inlet manifold. Production costs were lowered and the engine was quieter.

All this and a quite good description of the K-Series engine is at

Do you think you can have too much information?

Regards, Kes.

Kes, great link !! Thanks !!
Dieter Koennecke

This thread was discussed between 26/06/2001 and 29/06/2001

MG MGF Technical index

This thread is from the archive. The Live MG MGF Technical BBS is active now.