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vacuum throttle stop 185.
http://www.gt4dc.co.uk/forum/viewtopic.php?f=13&t=7599
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Author:  Nibbles [ Sat Apr 23, 2016 8:46 am ]
Post subject:  vacuum throttle stop 185.

I'm just wondering why these are fitted when there's a perfectly good idle control valve.
Firstly, which models are they fitted to, so far i have found them on dc/cs models.

If it is cs/rc only then was this a homologation device as an antilag throttle opener ?

Author:  Sunny [ Sat Apr 23, 2016 11:05 am ]
Post subject:  Re: vacuum throttle stop 185.

Hi,

nor sure what you are talking aboutm, do you mean the little damper on the TB connected to the intake manifold to find on the ST205 too?

greetz

Author:  Nibbles [ Sat Apr 23, 2016 1:42 pm ]
Post subject:  Re: vacuum throttle stop 185.

It's a small diaphragm which springs the throttle open a little, and is retracted with vaccum.

Image

Just to persuade myself I'm not going mad, I've just checked there isn't one on any of my cars.
I did find a 205 throttle body with one fitted so it seems it's not just on 185's. It could be a WRC one of course as I did have a WRC engine pass through.
A google image search for gt4 throttle body showed load of pictures but not one with one of these attached.

Author:  Diceman [ Sat Apr 23, 2016 6:26 pm ]
Post subject:  Re: vacuum throttle stop 185.

I think this is UK only.
IIRC the UK version has EGR and I understood it was related to this.

I don't think my My Rc has it.

Author:  Sirius [ Sat Apr 23, 2016 10:12 pm ]
Post subject:  Re: vacuum throttle stop 185.

Yes this is a UK/NonJDM thing I believe.

My ST185 didn't have this but my ST205 did before the engine change. As above I could only work out that it was linked in some way to the EGR system.

Author:  Nibbles [ Sat Apr 23, 2016 10:56 pm ]
Post subject:  Re: vacuum throttle stop 185.

It seems it's also fitted to many non turbo celicas as well soit seems it not a device for homologation. (I was guessing a rally version with a much bigger opening and controlled by ecu).

Author:  two_OH_five [ Sun Apr 24, 2016 12:04 pm ]
Post subject:  Re: vacuum throttle stop 185.

It's probably some sort of emissions thing but it might be a mechanical sympathy enforcer.

My Mondeo also had a similar setup as does mum's Fiesta. On those the effects are only really noticeable on gear changes where the effect is to hold high rpm during gear changes effectively making you shift slower.
Disabling the Mondeo version decreased shifting time by a couple of seconds but I didn't notice much difference on the four

Author:  Sunny [ Mon Apr 25, 2016 7:38 pm ]
Post subject:  Re: vacuum throttle stop 185.

Hi,

that a export vehicle comfort thing, and the answer is simple

it damps and delays when you kick the throttle body

not used in japan which makes it simple to identify a jdm intake manifold (just one connector -> for the fuel press regulator, export has a second one for that damper nest to it)

greetz

Author:  darrylp [ Mon Apr 25, 2016 8:50 pm ]
Post subject:  Re: vacuum throttle stop 185.

It's a CS & RC fitted device. Basically whilst the inlet is above atmosphere ( ie boost ) it keeps throttle open a tad to slowly drop pressure, rather than a snapped shut throttle which will over boost the charge cooler. This in turn then opens waste gate thus loosing boost rapidly, by slowing the turbine side.

The CS & RC have larger compressor wheel that has more momentum, the up and down in rpm is not good for longevity. For the 205 turbo they introduced a blow off valve. This is in effect an early version of a blow off, just putting it in the engine as the flap meter doesn't take kindly to dumping to atmosphere which causes over fuelling.

--
Darryl

Author:  Diceman [ Tue Apr 26, 2016 4:51 pm ]
Post subject:  Re: vacuum throttle stop 185.

Just checked and my RC doesn't have it.

Author:  two_OH_five [ Tue Apr 26, 2016 9:42 pm ]
Post subject:  Re: vacuum throttle stop 185.

I wonder if the egr system is active under high load and they needed a way to purge exhaust gas from the manifold if you lift off and return to idle.

Sort of makes sense but I have no idea what the egr strategy looks like

Author:  Nibbles [ Tue Apr 26, 2016 10:24 pm ]
Post subject:  Re: vacuum throttle stop 185.

If it's plumbed from the manifold, lifting off will inevitably generate a vaccum and return the throttle stop to minimum making it somewhat useless - unless there's a small orrifice making it operate slowly.
The only purpose I can see is cracking the throttle open for cranking / starting.

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