Dan's 4000CS Quattro 20vt Turbo Swap

[vt10vt]

To clarify, could I splice the MS3Pro CKP+ Wire (which is the wire the MS3 instructions say to use for a hall sensor - see below) with either the Mac-14 ECU Hall Sensor Timing Signal (Pin #27) or RPM Sensor Signal (Pin #11)? If so, which one #27 or #11? There is also a Tachometer wire (#7) from the Mac-14 ECU that I assume goes to the tachometer and a Ignition Module Control wire (#22).

The MS3Pro EVO manuals states the following:

4.3.4 Fuel only installations
CDI ignitions send a high voltage pulsed signal, from 300 to 600 volts, to the coil. You do not want to try to get a tach signal from the coil by any means when using this sort of ignition, including external adapter boxes. Instead, use the ignition box’s tach output wire to the CKP+ instead if you are using a distributor advance mechanism to control timing and just want the MS3Pro to control fuel. Do not use the CKP- wire or the CMP+ and CMP- wires.

The hall sensor timing output is only 5v, you need 12v. The RPM sensor signal is a VR signal and is 135 teeth/rpm which won't work for both of those reasons. The tachometer wire may work, but I would and go to the coil terminal; I've done a couple MS setups that way with perfect results, and it's the 'correct' way to do it for MS fuel only.

You're basically picking up output of the ECU telling the coil to fire which is a nice, clean, strong 12v square wave. You could also splice into this at the ECU (Coil output) but there's a lot more upside than downside to running a separate wire/ring terminal from the MS ECU to the coil.

[TrailAgent]

"You're basically picking up output of the ECU telling the coil to fire which is a nice, clean, strong 12v square wave."

Got it! Thanks for the clear explanation.

[TrailAgent]

Just so I make sure I understand, I would wire the MS3 CKP+ wire to the screw terminal on the coil where the blue/gray wire is connected from the ignition control module (terminal on the right in the image below).

[vt10vt]

Just so I make sure I understand, I would wire the MS3 CKP+ wire to the screw terminal on the coil where the blue/gray wire is connected from the ignition control module (terminal on the right in the image below).

Yep you've got it!

[TrailAgent]

Do you use an existing Coolant Temperature Sensor or install a separate one for the MS ECU? I have two unused sensors that could work or serve as the location for a new sensor.

Temp Sensors by TrailAgent, on Flickr

[DE80q]

I used a temp sensor from an NG to feed the MS. Works really well, and fit the factory 10mm thread.

[TrailAgent]

I used a temp sensor from an NG to feed the MS. Works really well, and fit the factory 10mm thread.

I guess the question is whether I can use the sensor by the yellow arrow or instal a sensor at that spot. If I recall, the sensor by the red arrow is an oil pressure sensor. I think the sensor by the yellow arrow is the after-run temp sensor. If that is true, then my mechanic used a different temp sensor for the after-run fan.

[DE80q]

The one at the yellow arrow is a switch, not a sensor.

[TrailAgent]

Thanks!

[TrailAgent]

Reading through the MS3PRO EVO manual, I see that it now handles 135 teeth/rpm directly and that if I connect CKP to the sensor that counts the flywheel and the CMP wire to the one tooth trigger on the flywheel, I can get sequential fuel rather than batch fuel. Is there any advantage to sequential fuel over batch?

[DE80q]

Pretty much every possible advantage. Finer tuning being the major one. I ran batch for a while on mine, and could never get it quite right. Now that I'm running fully sequential, it's spot on.

[TrailAgent]

Pretty much every possible advantage. Finer tuning being the major one. I ran batch for a while on mine, and could never get it quite right. Now that I'm running fully sequential, it's spot on.

Any advice you can share on how you wired it up? I'm having a tough time translating between the Audi 200 Bentley manual and the MS3 Manual.

Would I connect the CKP+ wire to the Hall Sensor signal wire? I haven't figured out exactly where to connect the CPM wire.

[DE80q]

Honestly, mine was done as stand alone right away. I'll have to look up the terms again. Hopefully shawn will chime in again. He was the wiring guy in my build first time around.

On a second thought though, make sure the mspro is compatible with the VR sensors. I made hall sensor adaptors for mine and a couple others to use on MS3X.

[vt10vt]

Pretty much every possible advantage. Finer tuning being the major one. I ran batch for a while on mine, and could never get it quite right. Now that I'm running fully sequential, it's spot on.

Any advice you can share on how you wired it up? I'm having a tough time translating between the Audi 200 Bentley manual and the MS3 Manual.

Would I connect the CKP+ wire to the Hall Sensor signal wire? I haven't figured out exactly where to connect the CPM wire.

You're still planning on using the MAC ECU for ignition correct? In that case you'll need to split VR signals which is doable, but introduces a large source of potential problems if not done correctly.

The 135 tooth setup on MS3 is still experimental; have you confirmed with anyone that the functionality is solid?

Honestly, if you're keeping the MAC for ignition duty, I would just run the basic fuel-only setup. Getting sequential fuel isn't a big enough benefit (on a 20vt, in my experience/opinion) if you're still stuck with a not-adjustable ignition map/curve. I would go basic fuel-only triggered off the coil or full sequential ignition/fuel. Half/half gives you most of the PITA of one without the benefits of the other.

To answer the question, CKP +/- would go to the 135 tooth VR sensor, the flywheel pin VR sensor would go into the CMP +/- and your hall sensor (distributor) would come in on Digital Frequency In 2. You'll need to make sure the config is correct as well because the ECU will be expecting a 5v signal on the CMP line out of the box. Again, if you're using all these for both MS and the MAC ECU they'll all need to be spliced/shielded appropriately. I'm assuming you'd just feed the hall 5v from your sensor voltage pin and ground it back to the sensor grounds, but I'd double check that because I don't know MS3 as well as I know the earlier systems.

[TrailAgent]

Shawn,

Thanks for the advice! I have a message into DIYAUTOTUNE support to ask the question of whether the tri-tach solution is viable. The manual says it is experimental. Given that this is my first EFI conversion, your advice is solid. I can always try fuel/ignition someday in the future.

[vt10vt]

Shawn,

Thanks for the advice! I have a message into DIYAUTOTUNE support to ask the question of whether the tri-tach solution is viable. The manual says it is experimental. Given that this is my first EFI conversion, your advice is solid. I can always try fuel/ignition someday in the future.

No worries happy to be a bit of help!

I bet the tri tach code is probably fine to use, but definitely worth checking into. Even so for fuel only I'd skip it, because say you do add ignition down the road you're still going to have to redo all your crank wiring to remove the splice you had to add.

You hit the nail on the head, I think with diy efi there's a lot of benefits to learning and going in stages, especially if you're going to wire/tune it all yourself.

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