VEMS help adding aux air valve and ALS trigger switch

Discuss VEMS and other standalone ECUs

VEMS help adding aux air valve and ALS trigger switch

Postby 88a5tq » Mon Apr 30, 2018 8:48 am

Hello everyone.

Is there a resource that explains what is needed to add an air valve to be controlled by the ecu as well as adding a switch for input? I'd like to find the info myself before putting together a plan and checking it with the VEMS forum for validity. These 2 additions will be for adding ALS during overrun conditions.

I prefer finding the info myself and compiling the plan first, and have it reviewed.

It was relayed to me by a very helpful source that I could accomplish a "pull-up" on one of my mcp chip inputs externally in order to switch it to ground for ALS activation. I have not found any further information on this yet.

"you can do it external to the ecu if you want.

wire a 2k ohm (or so, the value isn't super critical, just more than 1k and less than 10) between any 5v source (like the tps or the cps 5v supply line) and your analog input channel."

In my mind's eye I picture this as a simple circuit which takes the +5v supply from my oem 3b harness and grounds it directly to the mcp chip channel 1 in the VEMS aux harness, with a resistor in between. But in the case of my channel 2 for LC activation, it's switched from the VEMS to ground, through the clutch switch.

So with that in mind, do I take the formerly mentioned +5v supply wire and twist it to the same side as the mcp channel 1 wire of a butt connector and wire the other side of the connector to the ALS switch which will go to chassis ground? As usual, the forum says every picture I upload is "invalid" so I can't include my cheat sheet or circuit sketch. Someone on the VEMS FB group suggested wiring it like the efiexpress sketch for the LC circuit except replacing the 12v supply with the 5v tps supply I'll patch into on the OEM harness. The discussion has started on the FB group and the pictures are there as well.

Now that is for the switch-side of my overall project so how do I incorporate a VEMS-controled aux air valve to complete the ALS installation?

Again, I would rather find the source you all refer to so I can sketch it completely and have it reviewed later.

Please help if you can, thanks. I feel this particular information should be easily accessible to VEMS ecu owners because of how important it is to functionality expansion.
Janitor at large
1991 Audi 200 TQ HX35 (finally 56mm)
$500 butt-hurter
1988 Audi 5000 TQ
User avatar
Posts: 1518
Joined: Jul 16, 2014

Re: VEMS help adding aux air valve and ALS trigger switch

Postby ChrisAudi80 » Tue May 22, 2018 1:52 am

I would put this in the FB VEMS group. Not sure I understand what you want to do and why.
96 S6 auto
Posts: 736
Joined: Mar 2, 2013
Location: Bangkok, Thailand

Return to Standalone Engine Management

Who is online

Users browsing this forum: Bing [Bot] and 2 guests