My Water Meth Installation thread

[TonyHayers]

Sorry for lack of updates here - been ill with a stomach bug, thanks to the mini Hayers' disease carrying prowess - done a fair bit more on this so will post progress asap.

[Gavla]

Looking forward to the updates Tony

[TonyHayers]

Ok, the tricky bit. We need to tap a number of wires coming to/from the ECU: fuel injector + and - to get the injector duty cycle; the additional "aux input"; and 2 x switched 12V feeds (these could be got elsewhere but might as well source them from the same place imv).

We need to be able to get sight of the cables connected to specific pins of the ECU connectors so you can follow them down to an appropriate place to be able to tap into the wires. Aquamist gave me a diagram for the S5, which appears to have the same pinout but the wire colours are different (which is to be expected) - rarely a good idea to rely on the colour of a cable in any case



Getting access to the ECU itself is a bit of a pain (probably for good reason). The ECU is located in a box on the right hand side of the plenum chamber (between engine bay and passenger compartment). I followed some instructions from a JHM youtube tutorial (see below) and a PDF somone had made of an AZ forum post (the images in the forum post itself have been removed).



The steps to get access to the ECU are basically:

1) Remove the driver side wiper (this lets you access the screw at the back of the ECU cover by using an extension and threading it through the hole where the wiper arm is bolted on).
2) Unscrew the 5 screws of the ECU cover, which is simple enough, but the plastic "grille" piece at the bottom of the windscreen on my car has very little movement and I couldn't find any way to remove it - this makes it *near impossible* to remove the plastic ECU housing cover without damaging it. I had my windscreen replaced recently and I'm wondering if the muppets somehow accidentally glued this in :/
3) Unclip the metal retaining clip holding the ECU in place which allows you to lift the ECU unit with the loom attached out of the box.
4) Remove the metal "chastity belt" (with headless bolts) which surrounds the ECU connectors (thanks Audi). I followed the instructions here: http://www.vaglinks.com/Docs/Audi/B7/Au ... al_DIY.pdf - which involves cutting a slot in the bolts so they can be unscrewed, and then making a cut across a thin piece of the chastity belt so it comes apart enabling you to access the connectors. I used a multi-tool with the cutting disc.
5) Once the metal belt is removed you can slide off the plastic connector covers and finally unclip the ECU from the wiring harness. Probably put it somewhere safe

Now we can get sight of the wires connected to specific pins on the ECU connector and find a suitable place to tap them. Before doing the taps, feed the ends of the grey "ECU" and green "User" cables through the large rubber grommet on the side of the ECU box.

To tap into the cables without soldering or crimping, I used "Posi-tap" connectors which work pretty well but are quite bulky - so it's important to choose the tap location carefully so that the cables/connectors wont be under stress when you refit the ECU and loom into the box (it's a tight fit). I used plenty of cloth tape around the posi-tap connectors to prevent chafing/pinching.

Taps in place…



ECU cover refitted (note the new cables entering grommet)...



Starting to tidy up the water meth cable loom....



I found the red power cable wasn't long enough to route comfortably so I soldered an extension to it...



We now have the inputs for the water meth injection system and can test that the signals are being received correctly. To do this, remove the cover of the Aquamist control unit so you can see the "threshold" and "F-IDC" test LEDs. Then connect [only] the dash button, power connector, grey "ECU" cable and green "User" cable to the control unit. Start the engine and let it idle, you should see the F-IDC green led flickering, experiment with revving engine - the flicker rate should increase with engine speed and the brightness should increase with the duty cycle. If this is the case, then you've got the injector duty cycle sensing setup correctly. Next, turn the threshold trimmer all the way anti-clockwise (to lower the threshold to around 12%) and give it some beans - the orange "THRESH" led should light up as you cross the injector duty cycle threshold, which is what will eventually trigger our water meth injection.

Here's a little video of mine in action, it's pretty poor but you can see the green and orange leds doing their stuff. Note how the green led disappears for a while when revs are dropping off.

https://www.dropbox.com/s/s3vc56794et2j ... 7%2051.mov

With the main wiring stuff sorted, I moved onto routing the water meth pipe from boot to engine bay.

[Gavla]

Good progress there Tony! Well done for trying this out! Will the car need a new tune/map if your running a higher octane or will the ECU just adapt? Also what happens when you run out of Water/Meth?

[TonyHayers]

Good progress there Tony! Well done for trying this out! Will the car need a new tune/map if your running a higher octane or will the ECU just adapt? Also what happens when you run out of Water/Meth?

I haven't covered it here yet, but one of the things I've done is relocate the IAT sensor out of the MAF sensor, placing it *after* the water meth atomiser and just before the throttle body. The idea is that the IAT sensor can feed back the nicely cooled intake air temp to the ECU, which should increase timing accordingly. I'll need to do some logging of airtemps and timing angle to confirm that this is what is happening.

The higher octane bit is a bit complex I think. From what I've read, the *effective* higher octane is largely due to the dramatic expansion of water turning from a vapour to a gas during the cylinder combustion - rather than the methanol. The way I understand it (could be wrong!) is that, generally speaking, the Methanol is for cooling the intake air and the water is for cleaning and a bit of extra torque - although they obviously both do a bit of each.

The problem with a [permanent] remap to make the most of water meth, I think, is kinda what you mention above - what happens when you turn water meth off (or the tank runs empty). Some kind of switchable map system (I think revo do something like this?) might be nice, but I haven't investigated it much.

Re. the tank running empty, the Aquamist kit includes a tank level sensor which will tell the control unit to stop pumping something like 15 seconds after it detects a low tank level.

[Gavla]

I had REVO map before and I think you could use their SPS Box to quickly change maps through the OBD Port. But I'm not a fan of REVO maps due to lack of certain features/functionality. But in this case it might work well.

http://www.revotechnik.com/sps/

Might be worth chatting to MRC or AMD on maps to see if they can advise. I think my MRC Stage 2 map when in sport mode just adjusts the sensitivity of the accelerator and doesn't flip maps (might be wrong)

Keep up the good work!

[adsgreen]

Don't forget the rs4 has two ecus. Not sure if it has any bearing.

[adsgreen]

Posi taps are fab

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Mrc have multiple maps option based on the sport button.

[TonyHayers]

Don't forget the rs4 has two ecus. Not sure if it has any bearing.

Yeah, I meant to post a question about that actually. I know our cars have two Bosch MED9.1 ECUs in a master/slave configuration (as described in SSP) - but does this mean there are two separate physical metal ECU cases or is it that the ECU unit contains, say, two ECU circuit boards? It would seem to me that there should be two physical ECU units but there's certainly only one located under the main ECU cover, which I assume is the master due to all the sensor inputs. I've defintely hooked up to the IDC though, but it would be good to know for sure the ECU setup.

Where's the mystery slave device located, anyone?

[TonyHayers]

Mrc have multiple maps option based on the sport button.

Ooh, now, we're talking

[Gavla]

Mrc have multiple maps option based on the sport button.

Nice good to know - maybe then there is a possibility to hook something up on one of the spare dash buttons?

[TonyHayers]

So, next step was running the water meth line from the boot to the engine bay (although I actually started from the engine bay and worked back).

The photos show the path I followed, which was to follow one of the hard fuel lines from engine bay down into the driver side wheel arch, over drive shaft and then through the right-hand side undertray to the fuel filter, then up past fuel pump sender and through cover underneath rear right seat and then follow the wiring looms behind the side bolster into the boot.

I used some hard plastic conduit to cover the nylon pipe to give it a little protection from chafing: http://www.ebay.co.uk/itm/261025741528? ... 1439.l2649

Into wheel arch from engine bay and cable tie to hard fuel line...



Follow the fuel line into undertray towards fuel filter...



To save having to remove the undertray, I taped the tubing to some electricians cable pulling rods which made it easy to thread the pipe down towards the fuel filter...



Exiting undertray...



Up past fuel pump sender underneath rear bench...



The conduit was too thick to get under the cover seal, so I stripped off a section and it fitted nicely into the cut out...



Plenty of cloth tape to cover sharp edges...



Next up, the engine bay work.

[TonyHayers]

Don't forget the rs4 has two ecus. Not sure if it has any bearing.

Yeah, I meant to post a question about that actually. I know our cars have two Bosch MED9.1 ECUs in a master/slave configuration (as described in SSP) - but does this mean there are two separate physical metal ECU cases or is it that the ECU unit contains, say, two ECU circuit boards? It would seem to me that there should be two physical ECU units but there's certainly only one located under the main ECU cover, which I assume is the master due to all the sensor inputs. I've defintely hooked up to the IDC though, but it would be good to know for sure the ECU setup.

Where's the mystery slave device located, anyone?

Just to answer my own question it looks like the slave Ecu is simply mounted between the battery charge terminals in the plenum - dunno how I missed it tbh!

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I thought something like that - the part numbers are identical (just one with a jumper to set it to 'slave' mode) so would expect two physical ecu's. I don't think the ssp would document the secondary ecu can bus if one physical unit.