Photo of Vacum lines After removing secondaries 1994 !!

[5ABI VT]

[5ABI VT]

Think I found it. Looks like a vaccum line connects to here from the secondary vaccum actuators. Since I've phlled the secondaries and lines.. I'm guessing I should plug it so it would think the vaccum is holding or does it matter ?

[Dynomite]

I think that is the Diagnostic Vacuum Sensor (Manifold Differential Pressure Switch) which is normally under the ECM on 90's and 91's. Apparently that is under the Plenum on the 94?



Diagnostic Vacuum Sensor (Manifold Differential Pressure Switch) on a 91' located under the ECM
vacuum connection left open with elimination of secondary vacuum system.


Leave that Diagnostic Vacuum Sensor (Manifold Differential Pressure Switch) Vacuum open (unplugged). The vacuum line from the Drivers Side vacuum canister has a "T" from which a vacuum line was connected to this Diagnostic Vacuum Sensor .

Secondary Vacuum System


The Differential Pressure Switch looks a lot like the MAP (Manifold Absolute Pressure) bolted to the rear of the Plenum having this vacuum line attached.

[5ABI VT]

Thanks ! I was wondering if the connection should have vacuum or left open etc. Since there is a nipple left open on the drivers side from secondary removal I was thinking I could route a hose into there if required. Sounds like Ill leave it open.

view a little further back of where its mounted on my 94.

[Dynomite]

Thanks for that photo...good stuff to know...another little difference between model years

Originally Posted by 5ABI VT

Thanks ! I was wondering if the connection should have vacuum or left open etc. Since there is a nipple left open on the drivers side from secondary removal I was thinking I could route a hose into there if required. Sounds like Ill leave it open.

view a little further back of where its mounted on my 94.

[5ABI VT]

Originally Posted by Dynomite

Thanks for that photo...good stuff to know...another little difference between model years

Ill snap a photo of the vaccum line. It looks like a spiral like the evap that goes to the plenum but a smaller diameter.

Im just curious about leaving the connection open... would that not tell the ecm that there is no vaccum ? Would it cause the pump to run non stop? Or is all this removed in the chip when programmed to run with no secondaries? I did ask Marc as well if it was as he did do my chip for secondary removal. Im just curious about its function.

[Dynomite]

Originally Posted by 5ABI VT

Ill snap a photo of the vaccum line. It looks like a spiral like the evap that goes to the plenum but a smaller diameter.

Im just curious about leaving the connection open... would that not tell the ecm that there is no vaccum ? Would it cause the pump to run non stop? Or is all this removed in the chip when programmed to run with no secondaries? I did ask Marc as well if it was as he did do my chip for secondary removal. Im just curious about its function.

Marc Haibeck has mentioned to me and to Paul that port can be just left open. Marc can modify a Chip to account for secondaries eliminated. I think you WILL NEED that chip.

[5ABI VT]

Originally Posted by Dynomite

Marc Haibeck has mentioned to me and to Paul that port can be just left open. Marc can modify a Chip to account for secondaries eliminated. I think you WILL NEED that chip.

Oh sorry I just typed it all wrong, I DO have a chip for eliminated secondaries I was just wondering if turning off this sensor was already a part of it.

[Dynomite]

Originally Posted by 5ABI VT

Oh sorry I just typed it all wrong, I DO have a chip for eliminated secondaries I was just wondering if turning off this sensor was already a part of it.

I am not sure if that is required in the chip or just not required to do anything with that open port. I am sure that vacuum port on the Differential Pressure Switch is just left open in any event.

I could plug that vacuum line on my 90' and leave that Differential Pressure Port OPEN and see what happens easy enough since that Differential Pressure Switch is under the ECM

This is on my 91' with Secondaries Eliminated. You see the open port on the Differential Pressure Switch.

[GOLDCYLON]

Originally Posted by Paul Workman

A LOT less cluttered with the evap and secondaries stuff outta thar!

Clean Clean Clean Paul !