AAH 2.8 V6 on megasquirt

Addicted · 28-10-13, 11:11 AM

Been working on this for quite a while. As far as I can tell no one has yet converted the Audi V6 to run on megasquirt, certainly not the 12v.

Just wondering if anyone is interested in this, as I'm thinking of documenting my conversion on here. I intend to make this 'plug and play' using the factory loom etc.. just unplug the Hitachi MMS200 and plug in the fully mappable Megasquirt ECU.

At the same time I'm going to impliment an installation of Megashift. This is a automatic transmission ECU related to the Megasquirt that I will use to control my 097 4 speed auto. This is also fully mappable and comunicates with the Megasquirt ECU via CAN. This should also be plug and play..

Ben · 28-10-13, 12:35 PM

Quote:

Originally Posted by Addicted

Just wondering if anyone is interested in this, as I'm thinking of documenting my conversion on here..

Yes

Hanuman · 28-10-13, 01:30 PM

Some of this may be of use to me-

1993 2.8V6 quattro

as an alternative to throwing a ABH in the front

Addicted · 28-10-13, 01:42 PM

Well, a bit of background.. my engine is a 2.8 AAH from a 92 Audi 80 (awesome car) with a 097 4 speed auto box. I transplanted it into my type 81 saloon (replaced the dead 1.6)

The problem is that when I did the transplant I did away with a lot of emisions stuff AND repositioned the MAF (under the dash now, next to the ECU)

Ever since it has never run as well as it did in the 1992 chassis. After years of tinkering by me (and 034 Motorsport) the conclusion was that the modifications were outside the parameters that the MMS200 ECU could cope with.

I already run Megasquirt on a couple of other cars so I'm pretty familiar with it, so that was the obvious choice as a replacement for the Hitachi.

I really really don't want to build a new loom, I also don't want to totally disable the car while doing the conversion. So the plan is to make it plug a play. I've got a 'spare' Hitachi ECU that I intend to butcher for its connector. That way I can swap between the Hitachi and Megasquirt in a matter of minutes.

Addicted · 28-10-13, 01:52 PM

The first snag.. (this is the same snag that has prevented users in the Megasquirt community converting this engine in the past)..

The Hitachi uses the most ridiculous 'triple tach' system for measuring engine speed and TDC location. The 12v V6 shares this system with the 7A 20v Turbo..

It uses one VR (variable reluctor) sensor to measure the ring gear teeth (both V6 and 5 cylinder have 135 teeth)
It uses a second VR sensor to 'see' a dowel pin pressed into the flywheel 62 degrees BTDC
It then uses the third sensor (a hall sensor this time) to monitor the camshaft rotation so that it can work out where the firing cycle is (each cylinder has 2 TDC, for ignition, one exhaust, the cam sensor tells the ECU which is which)

However.. when Audi decided to fit this system to the V6 in a moment of madness they did away with the DTC pin and instead machined a slot in one of the crankshaft counterweights and repositioned the second VR sensor to 'see' it there..

Addicted · 28-10-13, 02:51 PM

So whats the problem?

Well the problem is that Megasquirt, just all other after market ECUs, is not designed to work with Audi's cock eyed system.. what Megasquirt wants to see is a single input from what is referred to as a toothed wheel..

Toothed wheels come in many formats. The idea is that you have a VR sensor counting the number of teeth on a wheel i.e 45 or 36.. you tell the ECU how many teeth there should be and then it simplys uses that information to calculate RPM.

For the ECU to know where TDC is you 'simply' remove one of the teeth. Again, you tell the ECU that a tooth is missing, and you tell it how many degrees BTC that missing tooth is..

Most 'modern' engines have a toothed wheel built in somewhere, I know that later 5 cylinders actually have it built into the rear crankshaft seal!

So the trick is to take the 3 signals from the factory sensor setup and put them into a hat, not any ordinary hat, a magic hat.. then say the magic word and out comes a single signal that looks like its being generated by a toothed wheel. This can be then fed into the new ECU and away you go..

Luckily for us Audi folks a good chap called Jean Belanger (www.jbperf.com) created that magic hat for us. Its called a Wheel Translator board. You simply connect the 3 audi sensors to it and it ouputs the toothed wheel signal. I won't go into how it does it, like I said, there's magic involved..

Addicted · 28-10-13, 03:06 PM

Snag number 2..

This is only a snag for the V6. Like I said earlier, those wise folks at Audi decided to use a notch in a crankshaft counterweight as the TDC mark. The problem is that VR sensors are designed to generate a small voltage when they are brought into close proximity to steel.. this means that the TDC VR Sensor can not only see the TDC notch, but it also sees the actual counterweight! to compound the issue the Audi engineers saw fit to drill a hole into the counterweight (for a locking pin) and the VR Sensor also sees the hole!

The yellow trace is the signal from the crankshaft sensor, what you see is a negative pulse at the start of the counterweight, then an AC pulse which is the TDC notch, then another AC pulse which is the locking hole, then a positive pulse that is the end of the counterweight.
The blue trace is 'after the magic' (in this case an LM1815 chip) it shows three +5v pulses (TDC notch, locking hole, counterweight)
The pink trace is the hall sensor on the camshaft (note how long that signal is)

So there you have it.. the sensor now sees three events per crankshaft rotation instead of one per.. and the ECU has no way of knowing which of the 3 'blips' is the one it needs..

Time for more magic.. (to be exact, not magic, LOGIC)

This is the bit I've just figured out and proved this weekend.. the third signal in our little story is the hall sensor attached to the cam (pink trace it picture above). This sensor is setup to give a signal at TDC, however, due to cambelt stretch etc etc this signal is not considered to be acurate enough to be used for ignition timing. Instead it gives a loong signal in the area around TDC.
By using electronic LOGIC gates I've created a little simple circuit that combines (AND gate) the crank sensor 'blips' with the cam sensor signal to produce just one signal exactly 62 degrees BTDC. The AND gate simplies says if signal 1 is +5v AND signal 2 is +5v then my output will be +5v. I'm feeding the AND gate with the blue and the pink signals in the picture above. You will see there is only one point in time where both the blue and the pink traces are at +5v. At that point the AND gate will output +5v.

Forgive the blurring picture, and the fact that some of my trace colours have changed. In this picture the blue trace is the output from the AND gate, as you can see there is now only one signal, not only that, it lines up perfectly with the AC signal from the crankshaft sensor that defines 62 degrees BTDC.. the signal from the locking hole and the counterweight are ignored..

So thats where I am now.. now its time to configure my actual Megasquirt ECU..

msh · 28-10-13, 06:38 PM

Quote:

Originally Posted by Addicted

Well the problem is that Megasquirt, just all other after market ECUs, is not designed to work with Audi's cock eyed system.. what Megasquirt wants to see is a single input from what is referred to as a toothed wheel..

Sucks to be you - you should choose VEMS, if you want plug'n'play solution for old audi engine, not crappy megasquirt.

sinbin5t · 28-10-13, 07:55 PM

wow thats very interesting, must say it looks like its on life support but then i am a technophobe and not clued up in these things but i think you must be very clever to do this stuff, hope you get where you want to

Addicted · 28-10-13, 08:09 PM

Quote:

Originally Posted by sinbin5t

wow thats very interesting, must say it looks like its on life support but then i am a technophobe and not clued up in these things but i think you must be very clever to do this stuff, hope you get where you want to

I'm not clever! Im just lucky to work with people who have been happy to guide me throught it..

28-10-13, 01:30 PM	#3
Hanuman Trickster Classic Audi Club Member Join Date: May 2009 Location: Heckling from the cheap seats, Phnom Penh, KoW Posts: 7,006	Some of this may be of use to me- 1993 2.8V6 quattro as an alternative to throwing a ABH in the front __________________ I wish they would keep the damned Chinese away now that I can go home, so that I can enjoy Fish amok and a draught Angkor

28-10-13, 01:42 PM	#4
Addicted Grown up member Classic Audi Club Member Join Date: Oct 2008 Posts: 591	Well, a bit of background.. my engine is a 2.8 AAH from a 92 Audi 80 (awesome car) with a 097 4 speed auto box. I transplanted it into my type 81 saloon (replaced the dead 1.6) The problem is that when I did the transplant I did away with a lot of emisions stuff AND repositioned the MAF (under the dash now, next to the ECU) Ever since it has never run as well as it did in the 1992 chassis. After years of tinkering by me (and 034 Motorsport) the conclusion was that the modifications were outside the parameters that the MMS200 ECU could cope with. I already run Megasquirt on a couple of other cars so I'm pretty familiar with it, so that was the obvious choice as a replacement for the Hitachi. I really really don't want to build a new loom, I also don't want to totally disable the car while doing the conversion. So the plan is to make it plug a play. I've got a 'spare' Hitachi ECU that I intend to butcher for its connector. That way I can swap between the Hitachi and Megasquirt in a matter of minutes. __________________ 1985 Type 81 2 door 2.8 V6 1983 Golf GTI track weapon 1977 Scirocco G60 1968 Sand Rail 2006 A4 2.0 TDI Avant = DEAD due to oil pump failure.. then alive.. then DEAD due to cam belt tensioner failure! and ALIVE again!!!

28-10-13, 01:52 PM	#5
Addicted Grown up member Classic Audi Club Member Join Date: Oct 2008 Posts: 591	The first snag.. (this is the same snag that has prevented users in the Megasquirt community converting this engine in the past).. The Hitachi uses the most ridiculous 'triple tach' system for measuring engine speed and TDC location. The 12v V6 shares this system with the 7A 20v Turbo.. It uses one VR (variable reluctor) sensor to measure the ring gear teeth (both V6 and 5 cylinder have 135 teeth) It uses a second VR sensor to 'see' a dowel pin pressed into the flywheel 62 degrees BTDC It then uses the third sensor (a hall sensor this time) to monitor the camshaft rotation so that it can work out where the firing cycle is (each cylinder has 2 TDC, for ignition, one exhaust, the cam sensor tells the ECU which is which) However.. when Audi decided to fit this system to the V6 in a moment of madness they did away with the DTC pin and instead machined a slot in one of the crankshaft counterweights and repositioned the second VR sensor to 'see' it there.. __________________ 1985 Type 81 2 door 2.8 V6 1983 Golf GTI track weapon 1977 Scirocco G60 1968 Sand Rail 2006 A4 2.0 TDI Avant = DEAD due to oil pump failure.. then alive.. then DEAD due to cam belt tensioner failure! and ALIVE again!!!

28-10-13, 02:51 PM	#6
Addicted Grown up member Classic Audi Club Member Join Date: Oct 2008 Posts: 591	So whats the problem? Well the problem is that Megasquirt, just all other after market ECUs, is not designed to work with Audi's cock eyed system.. what Megasquirt wants to see is a single input from what is referred to as a toothed wheel.. Toothed wheels come in many formats. The idea is that you have a VR sensor counting the number of teeth on a wheel i.e 45 or 36.. you tell the ECU how many teeth there should be and then it simplys uses that information to calculate RPM. For the ECU to know where TDC is you 'simply' remove one of the teeth. Again, you tell the ECU that a tooth is missing, and you tell it how many degrees BTC that missing tooth is.. Most 'modern' engines have a toothed wheel built in somewhere, I know that later 5 cylinders actually have it built into the rear crankshaft seal! So the trick is to take the 3 signals from the factory sensor setup and put them into a hat, not any ordinary hat, a magic hat.. then say the magic word and out comes a single signal that looks like its being generated by a toothed wheel. This can be then fed into the new ECU and away you go.. Luckily for us Audi folks a good chap called Jean Belanger (www.jbperf.com) created that magic hat for us. Its called a Wheel Translator board. You simply connect the 3 audi sensors to it and it ouputs the toothed wheel signal. I won't go into how it does it, like I said, there's magic involved.. __________________ 1985 Type 81 2 door 2.8 V6 1983 Golf GTI track weapon 1977 Scirocco G60 1968 Sand Rail 2006 A4 2.0 TDI Avant = DEAD due to oil pump failure.. then alive.. then DEAD due to cam belt tensioner failure! and ALIVE again!!!

28-10-13, 03:06 PM	#7
Addicted Grown up member Classic Audi Club Member Join Date: Oct 2008 Posts: 591	Snag number 2.. This is only a snag for the V6. Like I said earlier, those wise folks at Audi decided to use a notch in a crankshaft counterweight as the TDC mark. The problem is that VR sensors are designed to generate a small voltage when they are brought into close proximity to steel.. this means that the TDC VR Sensor can not only see the TDC notch, but it also sees the actual counterweight! to compound the issue the Audi engineers saw fit to drill a hole into the counterweight (for a locking pin) and the VR Sensor also sees the hole! The yellow trace is the signal from the crankshaft sensor, what you see is a negative pulse at the start of the counterweight, then an AC pulse which is the TDC notch, then another AC pulse which is the locking hole, then a positive pulse that is the end of the counterweight. The blue trace is 'after the magic' (in this case an LM1815 chip) it shows three +5v pulses (TDC notch, locking hole, counterweight) The pink trace is the hall sensor on the camshaft (note how long that signal is) So there you have it.. the sensor now sees three events per crankshaft rotation instead of one per.. and the ECU has no way of knowing which of the 3 'blips' is the one it needs.. Time for more magic.. (to be exact, not magic, LOGIC) This is the bit I've just figured out and proved this weekend.. the third signal in our little story is the hall sensor attached to the cam (pink trace it picture above). This sensor is setup to give a signal at TDC, however, due to cambelt stretch etc etc this signal is not considered to be acurate enough to be used for ignition timing. Instead it gives a loong signal in the area around TDC. By using electronic LOGIC gates I've created a little simple circuit that combines (AND gate) the crank sensor 'blips' with the cam sensor signal to produce just one signal exactly 62 degrees BTDC. The AND gate simplies says if signal 1 is +5v AND signal 2 is +5v then my output will be +5v. I'm feeding the AND gate with the blue and the pink signals in the picture above. You will see there is only one point in time where both the blue and the pink traces are at +5v. At that point the AND gate will output +5v. Forgive the blurring picture, and the fact that some of my trace colours have changed. In this picture the blue trace is the output from the AND gate, as you can see there is now only one signal, not only that, it lines up perfectly with the AC signal from the crankshaft sensor that defines 62 degrees BTDC.. the signal from the locking hole and the counterweight are ignored.. So thats where I am now.. now its time to configure my actual Megasquirt ECU.. __________________ 1985 Type 81 2 door 2.8 V6 1983 Golf GTI track weapon 1977 Scirocco G60 1968 Sand Rail 2006 A4 2.0 TDI Avant = DEAD due to oil pump failure.. then alive.. then DEAD due to cam belt tensioner failure! and ALIVE again!!! Last edited by Addicted; 28-10-13 at 03:57 PM.

28-10-13, 07:55 PM	#9
sinbin5t 4 ring whore! Classic Audi Club Member Join Date: Jan 2010 Location: Where a spike points skywards Posts: 12,960	wow thats very interesting, must say it looks like its on life support but then i am a technophobe and not clued up in these things but i think you must be very clever to do this stuff, hope you get where you want to