Secondary throttle vacuum takeoff

[Brianabbot]

Hi, I've just fitted a new heater valve and while poking around I noticed that the secondary throttle takeoff pipe was just hanging down, looking at the manual it should be plugged into a reservoir just above the starter motor. So my question is how on earth do you plug it in, I can't even see the reservoir let alone find where the pipe goes. Any suggestions would be really appreciated.

Thanks
Brian

[Specky]

That's a tough one, its sorta squirreled away under the clam on the front left bulkhead...

let me have a think on how to reattach it to the black plastic reservoir...

Just thinking out loud... can you trace the other lines in... the ones that run in the engine bay

TTFN

[Specky]

Remove the wheel arch liner? Its gotta be worth a shot...

you could also replace the interlinking foam tube whilst your in there as its bound to have perished

and then fit Stainless steel fasteners

TTFN

[Enright]

Dave, I think you've got a different reservoir on your mind.

The secondary throttle reservoir is the small grey one under the intake plenum.
Admitedly, if you've never been in there to undo it in the first place, then it's going to be a bit of a nightmare to find.
The best route to it would be by reaching through the space near the coolant expansion tank. It may help to remove the intake pipe into the throttle body.
The small pipe pushes onto the reservoir from the coolant tank side. It's number 22 in the second diagram down on this page:

http://wikilec.9600.org/index.php/Engin ... components

To locate it you might need to get your mobile phone in there and look at the screen to get your bearings. Or even better, pick up one of those cheap endoscopes off ebay.

[Specky]

Enners,

You're right, I'm thinking of the other reservoir... Senior moment

TTFN

[Brianabbot]

Hi, good idea I hadn't though about an endoscope, either that or I need to find a gynaecologist who doesn't mind getting his hands dirty! I'll have a look for cheap endoscope first though I think. Looking at the end of the pipe I can see a faint impression from a clip so I'll have to get another one of those too. I guess it's a good thing I found it wasn't attached but it was one of those classic moments where I think 'I'll just quickly fit the heater valve - back in a minute'

Thanks for the help as always

[cliff]

Hi Brian,

this picture clearly shows the reservoir and throttle mechanism.

I just had a look and you can see it from the left hand side of the car. I have all of the intake ducting, water pipes and expansion tank off at the moment but it does look as if you should be able to get your hand in there and push it back on. Might be useful to have a younger son/daughter to assist.

Going to be fiddly so good luck.

[hodge]

Nice pics there, Ciff, of a usually very hard to see area.
The second photo has somehow ended up on it's side during the process of posting tho.
If you or someone could turn it 90 degrees left, it would correct it and help with the necessary visualisation required as the the OP fumbles around with their right hand, eyes closed trying to remember that image and what goes where.

[cliff]

Maybe this one is a bit clearer, can orientate from the rear bulkhead.

For info, my engine bay is like this at the moment.

[hodge]

Maybe this one is a bit clearer, can orientate from the rear bulkhead.

P3031891.JPG

[Brianabbot]

Hi, thanks so much for the pics, my endoscope camera thing arrived today so I'm going to have a go on Saturday, fingers crossed it goes on OK, the endoscope was only £7 and I plugged it into the laptop tonight and it was pretty good, it has LEDs round the lens with adjustable brightness so I'm hoping I can see a bit more this time.
Thanks
Brian

[Brianabbot]

this is one of those little jobs that i keep putting off, but as the car is all back together now I need to get it sorted out really. I just wonder though if someone could explain to me what the secondary throttle does - im not thinking of leaving the pipe off but im curious as to what its for. I dont have much experience with this type of thing but i would have thought it takes a bit of force to open 8 valves and im surprised that a vacuum would have enough power to do this. Is the normal state open and then the vacuum closes it for a short period on warm up or do they open and close during acceleration?

Any help as always would be greatly appreciated, Im trying not to ask too many questions!

Brian

[dapinky]

Brian,

The intake system is quite an odd affair on these engines (or I think so, anyway!).

Basically, there are 8 'pipes' going into 4 cylinders at the head (2 each) - one of these is always open, and those 4 join up to the main intake pipe, the other (all 4 are linked) have a secondary butterfly to open or close them as necessary.

The theory is that the air travelling into the head travels at high speed through a smaller aperture (helps get the boosted air into the cylinder quicker) - but the smaller aperture (primary throttle) has a limitation to the volume it can flow in the time between compression cycles at high revs.

Therefore, the secondary throttles open only when the revs get high enough, and there is sufficient vacuum in the plenum to operate the module....

it is the 'suck' of the air into the cylinders which provides the higher vacuum, and (If i remember correctly) it only happens at open throttle situations.

As such, without the system connected, the car will perform as any other unless you floor the pedal and get to high revs - then it will feel a bit strangled as not enough air gets into the engine (but I think that the ECU still thinks it is working, so pumps what it thinks to be the correct quantity of fuel into the engine, and it runs rich).

[Simon_P]

Therefore, the secondary throttles open only when the revs get high enough, and there is sufficient vacuum in the plenum to operate the module....

it is the 'suck' of the air into the cylinders which provides the higher vacuum, and (If i remember correctly) it only happens at open throttle situations.

Not quite (as you have full boost then)- There is a vac tank and a solenoid valve - When you hit 4200 revs the ecu switches the solenoid valve and the secondary throttle opens.
I only know cos I read the engine manual a couple of years ago

[dapinky]

There you go - I'm always learning.

I was only going from what I remembered reading when the one on my red car needed mending

[Simon_P]

Just found it - Section EC bottom of page 3 (I can't paste it here for some reason)
it is 5200 rpm according to that. (maybe you don't need to be on boost either - depends on the logic)

[Brianabbot]

It's all making a bit more sense now, I took it out for a quick spin Saturday after I finished putting it back together as in my excitement I'd forgotten about the vacuum pipe and it drove fine. I didn't really put my foot down as I really just wanted to check levels etc and see how how the car felt - I've never replaced radiator, thermostat, shocks etc before so I took it a bit easy, everything works as it should apart from the hazard lights which don't flash for some reason, the heated seat kit I put in was toasty so overall I'm pretty chuffed. Just a little oil leak from the o ring Bung thing now and a slight blow in the centre section along with trying to get the boot to sit a little more to the right to get the gap even and I'll be done - well for a week or so....

Thanks again for all the help
Brian

[Simon_P]

Hazard switch internals corrode - You need to take it to pieces and clean the copper wipers.

A bit of a fiddle but I'd choose that over reattaching the secondary throttle vac pipe!

[Brianabbot]

Thanks Simon, I get a similar problem on our printing presses, I normally end up looking on the floor for the spring and see saw bit when it all pings apart. Yes Im not looking forward to the vacuum pipe, Im hoping my 11 year old might want to help!

[Brianabbot]

All done, it was a bit of a nightmare but in the end I took off the coolant reservoir and a load of pipes and managed to get the vacuum pipe back on with a little Spring clip to hold it in place. I could just get my head down where the coolant tank was by laying flat across the engine bay, I also replaced the cas oil seal and the other Bung seal while I was there so all in all not a bad evenings work. Just need to get it out on the drive at the weekend and check/adjust the timing now. Thanks again for the help.