# mk4 megasquirt questions



## Withidlehands (Nov 29, 2007)

Alright I know what your thinking SEARCH. Well my questions are a little more in depth then searching alows.
First off I am running ms1 v3.57 on a mk4 aeg engine. Odd I know but the stock ecu douesnt have a map or e85 capacity.
So I guess my questions are thus:
does the stock alarm effect the stock ecu and is any of the wiring shared on mk4s? What are people running if they go standalone for that?
secondly I will be running waste spark. From looking around a bit does the stock AEG coil pack have built in igniters and if so does anyone know a recommended charge time? 
Also what does the exciter wire on the altonator want to see? switched ignition +12v?


_Modified by Withidlehands at 6:29 AM 2-18-2010_


----------



## need_a_VR6 (May 19, 1999)

*Re: mk4 megasquirt questions (Withidlehands)*

Most people piggyback on Mk4's due to the can based tach and DBW. 
The AEG coil has igniters, and should be very similar to how a VR6 coil works. I use 6ms cranking, 3.2ms running for those. 
Exciter needs to go through a led/light with ignition switched 12v, stock cluster led takes care of that.


----------



## ValveCoverGasket (Mar 20, 2002)

*Re: mk4 megasquirt questions (need_a_VR6)*

yeah i would probably t into the rpm, and then pull off the spark and fuel wires off to the MS. leave everything else in there, and pull out the check engine light


----------



## Withidlehands (Nov 29, 2007)

My car is not dbw since its an early mk4 (2000) so would it still be can based tach signal? Its a 5.9 ecu... If so, what signal does the tach need to see? I would prefer not to retain any of the factory engine harness... Thanks for all the help guys!!


_Modified by Withidlehands at 12:42 PM 11-13-2009_


----------



## need_a_VR6 (May 19, 1999)

*Re: (Withidlehands)*

Ah, if you're not DBW you might not have the can-bus tach. Check the Bentley for a dedicated wire running from the ECU to the tach part of the cluster in your model.


----------



## ValveCoverGasket (Mar 20, 2002)

*Re: (need_a_VR6)*

that should be a much easier setup, as far as the engine side is concerned. im not familiar with how it interfaces with the mk4 vehicle side.


----------



## need_a_VR6 (May 19, 1999)

*Re: (ValveCoverGasket)*

I try not to know but it finds me.


----------



## ValveCoverGasket (Mar 20, 2002)

*Re: (need_a_VR6)*








likewise
im about to embark on an ms adventure with my aeb passat, but the engine harness on that car is seperate from the vehicle harness for the most part... thats about as close to mk4 stuff as id like to get haha


----------



## Withidlehands (Nov 29, 2007)

*FV-QR*

Hey well im bumping this thread to figure out how to wire the CPS in a mk4 we keep getting mixed ideas as to how its done. Its a Aeg 8V
Oh and we kept the stock ecu to run idle and keep cruise and run the dash and MS runs spark and fuel.


----------



## need_a_VR6 (May 19, 1999)

*FV-QR*

Tap into the signal wires with two conductor twisted pair, and ground the shield of the new wire to the MS grounds.


----------



## Withidlehands (Nov 29, 2007)

*Re: mk4 megasquirt questions (Withidlehands)*

what do you mean by that? lamins terms?


----------



## need_a_VR6 (May 19, 1999)

*FV-QR*

Crank sensor wires, two are signal (VR+/-) and then one shield wire. You want to tap into the signal wires and run those to the MS (tach input and a ground). You also want to use shielded wire (two conductor plus shield) and ground the shiled at the MS. Can't spell it out much more without a picture.


----------



## Withidlehands (Nov 29, 2007)

well we are still running the factory ecu off it as well and havent had any luck getting a crank signal. We had it spliced into the factory wired as pin 1 ve-, pin 2 ve+, and pin 3 ground<- we didnt splice anything into this one as we have the ms grounded to the same place as the factory ecu... Im thinking maybe we only need to run one signal wire to the sensor from the ms???


_Modified by Withidlehands at 12:25 PM 2-17-2010_


----------



## need_a_VR6 (May 19, 1999)

*FV-QR*

You need both +/- as it's a differential sensor. The ground on the stock sensor is just the shield connection. 
Do you have a scope to see what's coming into the MS? There's a good chance you'll have to play with the pots, etc to get a good signal.


----------



## Withidlehands (Nov 29, 2007)

*FV-QR*

thanks to AutoCrosser11 we have the car running now. so thanks for the help guys.


----------



## Withidlehands (Nov 29, 2007)

*FV-QR*

Alright guys 1 more question. We are stuck on the TPS signal now, and AutoCrosser11 sent us his Firmware but we would really love to be able to figure out how to reverse the polarity of the TPS in the MS firmware as AutoCrosser11 has done in his. We calibrated the TPS backwards like DIY said and that doesn't work.


----------



## need_a_VR6 (May 19, 1999)

*FV-QR*

You can't run a reverse polarity TPS on MS1. You'll have to get a 0-5v signal from somewhere.


----------

