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Help please - vacuum connections after engine drop

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Old 05-17-2020, 03:15 AM
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NBL
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Default Help please - vacuum connections after engine drop

Just did a tip to manual conversion today (see other thread). Two vacuum lines are left and I cant find where to join them!

The first comes from the three-linkage right on top of the intake. The second comes out of the blower motor tube - it has a joiner on the end that looks quite specific. Searched and looked through the PEF but cant find it....thanks in advance.






Old 05-17-2020, 03:31 AM
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samurai_k
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Originally Posted by NBL
Just did a tip to manual conversion today (see other thread). Two vacuum lines are left and I cant find where to join them!

The first comes from the three-linkage right on top of the intake. The second comes out of the blower motor tube - it has a joiner on the end that looks quite specific. Searched and looked through the PEF but cant find it....thanks in advance.






The bottom pic is one that connects to your distributor. The top pic is one which you have a y connector likely to a vacuum solenoid or vacuum actuator depending on your setup. The vacuum system is actually a simple system. Follow the lines until they end at the valve where the motor creates vacuum or the other end which is through a solenoid and eventually to a actuator where it terminates.
Old 05-17-2020, 04:02 AM
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RicardoD
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My 1991 C2 Tiptronic does not have the black Y piece out front. Here i the picture of my C2 taken from the same angle.

On my 1990 C4 that black Y piece connects to the throttle body directly but not sure where it is on my C2.





Old 05-17-2020, 08:42 AM
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540964
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First photo...doesn’t that connect to the vacuum reservoir on the underside of the intake air filter box?


Old 05-17-2020, 11:11 AM
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LM964
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Originally Posted by 540964
First photo...doesn’t that connect to the vacuum reservoir on the underside of the intake air filter box?
Yes. When I switched away from the air filter box I had to blank the Y connector.
Old 05-17-2020, 11:51 PM
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nirich
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Default Vacuum lines

The first pic shows my T junction with the white line going to the carbon canister behind the airbox (see pic 2).
The red vacuum line (pic 3 with the upside down A) goes off behind the engine up against the insulation and then to the RH rear suspension (pic 4).
Where it actually goes i have no idea. Is this vacuum line setup unique to ROW cars?

The white vacuum line goes to the carbon canister behind the airbox. The red one joins up to a black line up against the engine insulation.

Back of the airbox.

Red vacuum line joins this line (the upside down A) up against the engine insulation.

It is routed around the suspension tower and i have no idea where it goes........yet.
Old 05-18-2020, 01:46 AM
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JohnK964
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My car MY91 C2 Tip Coupe had a diagram of the vacuum lines on the underside of engine deck lid

Not a very good picture
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RicardoD (05-18-2020)
Old 05-18-2020, 02:46 AM
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RicardoD
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I completely forgot about that diagram. Here is the one on my 1991 C2 Tip for reference. Looks the same. This is a USA car compliant with California emissions. This will be helpful for my intake rebuild in progress.





Last edited by RicardoD; 05-18-2020 at 04:38 AM.
Old 05-18-2020, 04:34 AM
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NBL
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You guys are awesome....will connect it tomorrow.....thanks a lot.
Old Yesterday, 02:39 PM
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LM964
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Resurrecting this post and thread, partly to ask a question and partly to answer a question within.

Trying to eliminate from my troubleshooting list any possible causes or contributions to my issue - throttle response lag, which is very noticable when changing down gears (throttle blip on change-down does not work - just feels like an 'empty stab' on the foot pedal. Wondering if any part of the engine vacuum system has a play in this. Been tracing all the vacuum components and (spaghetti) pipework for anything missing or disconnected. Any pointers gratefully accepted (vacuum related or otherwise).

To answer a question posted in this thread - the small plastic pipe off the 'T' piece from the top mounted vacuum valve, that then disappears into the rear of the engine bay, connects to the vacuum operated headlight raise/lover function (from the dash mounted up/down dial). Not sure if all 964's came with this.

Now to ask my own question; the other pipe from the same 'T' piece connects to the vacuum reservoir behind the air filter box - what does this do and what if I disconnect this and cap the pipe? Does this control any (air pressure related) function or element of the throttle body that may affect throttle response?

Thanks

Marcus
Old Today, 12:04 AM
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John McM
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The vacuum reservoir provides the power to actuate the resonance flap in the throttle body above 5,000rpm to improve power at high revs. The ECU actuates a solenoid to switch the power. I don’t think this would affect throttle response.

Last edited by John McM; Today at 12:06 AM.



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