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> Convert back to D Jet Fuel Injection-, Vacuum Line questions
young55961
post Jun 20 2026, 01:14 PM
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I’m working on the vacuum hoses and have a few questions.

1. **Cold Start Valve:** I believe the larger port connects to the Auxiliary Air Regulator (AAR). Where does the smaller port connect?
Attached Image

2. I’m missing the EGR valve, all of the metal vacuum lines, and the deceleration valve. Does that matter? Can I start the engine without them?

3. What is the middle port on the fuel rail for? Where should it be connected?
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Montreal914
post Jun 20 2026, 01:46 PM
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Your answer is in your post. (IMG:style_emoticons/default/smile.gif)

The cold start valve is an extra injector. It connects to that middle port you are showing in your second picture.

Here is an image taken from @JeffBowlsby website (link also attached).



https://bowlsby.net/914/Classic/TechNotebook.htm
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Montreal914
post Jun 20 2026, 01:59 PM
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picture...

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young55961
post Jun 20 2026, 02:24 PM
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QUOTE(Montreal914 @ Jun 20 2026, 02:59 PM) *

picture...

Attached Image


I have a middle port on each fuel rail. Should I use a T-fitting to connect them together?

I'm not sure what the purpose of these ports is. Are they for vacuum or pressure relief?

Also, what about my second question? Do I need the EGR valve and the metal lines, or can I run the engine without them?

Tks.
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young55961
post Jun 20 2026, 02:50 PM
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QUOTE(young55961 @ Jun 20 2026, 03:24 PM) *

QUOTE(Montreal914 @ Jun 20 2026, 02:59 PM) *

picture...

Attached Image


I have a middle port on each fuel rail. Should I use a T-fitting to connect them together?

I'm not sure what the purpose of these ports is. Are they for vacuum or pressure relief?

Also, what about my second question? Do I need the EGR valve and the metal lines, or can I run the engine without them?

Tks.

Sorry, I did not read you answer carefully.
Actually is the fuel supply line to the cold start valve.
I guest I can just plug the other one.


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wonkipop
post Jun 20 2026, 03:38 PM
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QUOTE(young55961 @ Jun 20 2026, 02:24 PM) *

QUOTE(Montreal914 @ Jun 20 2026, 02:59 PM) *

picture...

Attached Image


I have a middle port on each fuel rail. Should I use a T-fitting to connect them together?

I'm not sure what the purpose of these ports is. Are they for vacuum or pressure relief?

Also, what about my second question? Do I need the EGR valve and the metal lines, or can I run the engine without them?

Tks.


i would imagine the EGR is the same in principle as it is on the L Jets.
you don't need to have it connected or operational.
its purely vacuum operated - not electronically triggered.
although having said that i believe that the 2.0s had an air pump (smog pump) additional to the EGR. someone like @JeffBowlsby would know.
i would think neither is required for the engine to operate.
and......i think the EGR was only on californian cars anyway on both 1.8s and 2.0s.

you need the whole set up for the EGR inclusive of the rear muffler exhaust system with the EGR port. pretty rare item i would think. i have seen 1.8s with all the californian emissions gear intact documented in sales adds. but pretty rare these days for it all to be there. probably decommissioned in most cars when the rear muffler failed and a replacement without the port was fitted.
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young55961
post Jun 20 2026, 04:26 PM
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QUOTE(wonkipop @ Jun 20 2026, 04:38 PM) *

QUOTE(young55961 @ Jun 20 2026, 02:24 PM) *

QUOTE(Montreal914 @ Jun 20 2026, 02:59 PM) *

picture...

Attached Image


I have a middle port on each fuel rail. Should I use a T-fitting to connect them together?

I'm not sure what the purpose of these ports is. Are they for vacuum or pressure relief?

Also, what about my second question? Do I need the EGR valve and the metal lines, or can I run the engine without them?

Tks.


i would imagine the EGR is the same in principle as it is on the L Jets.
you don't need to have it connected or operational.
its purely vacuum operated - not electronically triggered.
although having said that i believe that the 2.0s had an air pump (smog pump) additional to the EGR. someone like @JeffBowlsby would know.
i would think neither is required for the engine to operate.
and......i think the EGR was only on californian cars anyway on both 1.8s and 2.0s.

you need the whole set up for the EGR inclusive of the rear muffler exhaust system with the EGR port. pretty rare item i would think. i have seen 1.8s with all the californian emissions gear intact documented in sales adds. but pretty rare these days for it all to be there. probably decommissioned in most cars when the rear muffler failed and a replacement without the port was fitted.

Thank you for the information.
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