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MG MGF Technical - Sticky Throttle

As I accelerate when my car has just been switched on, irrespective of whether its hot or cold, my revs take longer to drop when changing gear, but after afew gear changes everthing is fine. However when driving to work this morning, about 20mins into my journey, my car was idling at just under 2000 an when I changed gear the revs this time did not move, they would remain at about 3000 to 3500 or whenever I would change gear.

Has anyone had the same problem? If so how did you solve it?

An suggestions will be apperciated.

Olly.
O Scott

How old is the car?? could this be a warped throttle body??

i have had mine changed to the alloy throttle body, i think this can happen if the old one warps, maybe worth getting it checked, or perhaps someone may know the exact problems..

Nick
Nick Walters

Yes, lots of people, a sticky or warped throttle body is your cause. Have you got a K&N? if so you may have warped the plastic throttle body on your 1.8 (non VVC). If you dont have a 1.8, or have never played with the breathing then the throttle can be removed and cleaned. But if I were you I would go to MG Speed (advertized here) and get yourself a new trophy throttle body which will cure your ills and give you more BHP (price a little over £120 IIRC, easy novice fitment). One thing to try first is to reset the throttle position sensor by switching on the ignition until you get all the red lights (not running the engine) and press fully to the floor 5 times the accelerator- this resets the MEMS knolage of the throttle and may cure the fault for FREE!!!.

Will
Will Munns

My car is a '97 P 1.8i, with 45,000 miles. I do not have a K&N. I will reset the MEMS knolage at lunch time today and let you know how I get on.

Thanks for your quick response.
O Scott

IMO useless to reset MEMS in this clear case.

Get a Trophy TB or if you have some DIY skills, then dismantle the old plastic thingy complete until you hold the shaft for the butterly in your hands.
You'll see the problem and can clean and grease the bearings and inner rubber seals.

WD40 to the bearings from inside or outside is useless waste of oil also, cause WD40 will not get to the location were the sticking rubber seals are. Material from this rubber seal is rubbed off and 'adhered' (spelling?) to the rough surface of the brass shaft.

http://www.mgfcar.de/throttle/brass_cp_0454.jpg
http://www.mgfcar.de/throttle/sensor_cp_0459.jpg
http://www.mgfcar.de/throttle/segment_cp_0457.jpg
I'm sorry, only some poor quality pictures.
The 'lead-teflon bearings' inside the TB can't be seen here. They are from good quality and app 10mm deep. Though the outer design with the rubber parts together with the brass shaft makes the stick troubles.

I hope you can read/understand what I mean.

HTH
Dieter
Dieter Koennecke

I had similar-ish symptoms in an 8 month old VVC. Turned out to be a "knackered" throttle cable replaced free under warranty.
David Bainbridge

Dieter, I've not looked properly yet, so please forgive me if this seems completely insane, but do you reckon that the plastic throttle body could be drilled, the throat enlarged and a larger throttle butterfly inserted?

Yeah yeah, I know, easier to fit a Trophy TB, but just one of those wierd Friday afternoon ideas! ;o)
Rob Bell

i had same problem on 1997vvc will reccomended pressing accelerator 5 times which worked, but i had car serviced at B&G on wed and they replaced throttle cable and body i think and it is now more responsive!!! but its not an urgent thing if you want to live with it....

bash

r119 han
BASH

Selling my old throttle body for cheap price :)

say... 20 pounds?

Good condition. No sticking.

+ Postage. Hopefully around 6 pounds odd.
Hanah Kim

> wierd Friday afternoon ideas! ;o)

Nope, nearly impossible. You'd drill or lathe away the bearings and suck wrong air. Would be easier to converting the GM part.
Couldn't you paint a GM TB in black colour and let it look like 'original' ? ;)

Hanah,
to cheap if including the throttle sensor ;)
Or keep the sensor for later spare needs.
Dieter Koennecke

..further to BASH's comments, the blokes at B&G will probably tell you what's wrong just by pressing the throttle pedal. That's all the diagnosis time they needed for mine.
David Bainbridge

Hi Rob,

As Dieter already said; it's better you don't!
About 2 years ago I've tried it myself, on a lathe, and I've found out that the wall of the body become's so weak that it is nearly impossible to put the throttle body back on with no leaking or sticking (new made) throttle plate.
If you don,t wanna spend much money, and if you're a bit handy, you better go Dieter's way and buy a Opel TB, or a Volkswagen's (56 mm).
Arend Groen

Arend,
Rob's little problem is I think the usual MGCC competitions in the UK (sprint and hill climb) and their reasonable restrictions regarding modified cars.
Rob's favourite would be an easy swap/mount TB ;)

Ahhhhhm ;)
You mentioned Volkswagen TB (56 mm). ? *g*g*g*
Not that I want one, but ... which VW engine type do you refer to ?
:)))))))))))
Need more crazy enhancements @ http://mgfcar.de/throttle

Cheers
Dieter
Dieter Koennecke


If that fails, could be something to do with temp sensor playing up. Especially if the revs are slow to fall... but do return.

P.
Paul

Dieter,

About six months ago I found a VW TB at the scrapyard.
I am not shure of which engine it comes from, but I guess it is one of the early 16-valve engines as used AFAIK in the B-model Scirocco's.
It has a bore of 56mm, it is a little bit shorter then the Rover TB but it has the same mounting holes.
It needs a few modifications but that's no problem for you, is it?
My TB isn't ready yet because of very little spare time due to starting my own business, from januari on, this year.
When I am ready with it I will let you know how things are going, but I think it won't be before the end of summer.

Arend
Arend Groen

Shorter ? LOL, Scarlet did you read ??? ;)

Arend,
would be great if you could send a picture at any time for further identification.
If I find time then I'll have a visit to a german breaker for having a look.
Dieter Koennecke

Dieter, my spare TB is from replacing it with Trophy one. So I guess it still has a sensor attached to it?

Cuz I thought Trophy TB which costs around 115pounds come with a new sensor.

Regards,
Hanah

(please read upon crossmember)
Hanah Kim

Yep, you can bolt it off easy and keep for spare use.
http://www.mgfcar.de/throttle/throttle_sensor_4032.jpg
Dieter Koennecke

Bump !

I'm sorry for the inconvinience.
Dieter Koennecke

Dieter, can you find me an Mk1 centre console fascia? Please have a look for me.. thanks..

(stressed)
Hanah
Hanah Kim

Dieter, Arend, thanks for the info and for answering my mad Friday afternoon dreaming! LOL

I was interested in what would be possible, and am very interested to read that someone actually went out and attempted it!

I confess the reason for asking was born from idle speculation on my part on what could be done with the standard part specified on the MGF for the sprint rules. I now have a Trophy TB in my posession and will fit it for next season (and will then have to enter the road going modified class). Hey ho. Might as well find an old 1.8i head and get it gass flowed with larger valves in that case ;o) Anyone got a spare head knocking about?

Now what's all this about a VW TB???! 8o)
Rob Bell

This thread was discussed between 10/05/2002 and 17/05/2002

MG MGF Technical index

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