My Water Meth Installation thread

[TonyHayers]

First part of engine bay work was to fit a separate IAT sensor. I want the ECU to know about the nice cooled air which will be entering the intake manifold so it can adjust timing and make the most of it. The problem is that the RS4 has a combined MAF and IAT sensor and while I don't mind having water meth mist passing over the IAT sensor (simply a thermistor) - I don't want the mist to enter the little MAF sensor duct and potentially cause it to misreport air mass.

So, I bought a generic VAG IAT sensor for £15-odd from GSF (http://www.gsfcarparts.com/929vg0350), together with the connector and tails from Audi parts and the 6mm plastic protective conduit… (apologies for quality)



Edit: I should say, I tested the new IAT resistance compared to the MAF IAT resistance at various temperatures using a hairdryer, chiller spray and a multimeter and it acts well within the expected tolerances so all good.

To split out the IAT sensor from the MAF, we need to tap the MAF signal ground wire (pin 3) and cut/divert the IAT signal wire (pin 1) so that it now goes to our separate IAT sensor. By removing the connector cover and exposing the wires we can clearly see the wire colours that we need to intercept further down the loom...





Peel back the protective sleeve and *very* carefully cut the cloth tape and conduit to expose the wires...



Cut the purple and green wire and solder on one of the new IAT tails, so that the IAT signal will go from our new IAT sensor to the ECU. Tap into the brown and white cable (don't cut it - the MAF needs it!) and solder the other IAT tail...



Cover with heatshrink, wrap with plenty of cloth tape and pull back the rubber protective sleeve.

To fit the new IAT to the intake is pretty simple. I located it as near to the throttle body as I could - as well as keeping it out of the way so it doesn't get knocked/snagged with everyday use...





Done. Next, getting the FAV and atomiser jet installed.

[Timster]

This is brilliant Tony. Loving the concise updates.
I hope this works first-time, because you're gonna have a fault-finding headache if it doesn't

[TonyHayers]

This is brilliant Tony. Loving the concise updates.
I hope this works first-time, because you're gonna have a fault-finding headache if it doesn't

Hehe...

Spoiler alert: it does work

I'm just writing up the installation stages as and when I get a chance. I'll get to the good stuff soon I promise.

[Surrey Sam]

Fairplay Tony for giving this option a go, they're not cheap engines to go mucking about with.

I'm enjoying it being drip fed. Something to look forward to each time the thread gets bumped.

[Rick_RS4]

great writeup, looking at doing this myself too, does it use alot of meth on every day driving?

id put some thread lock or a nyloc nut on the IAT sensor, dont want a bolt down one of your cylinders

[TonyHayers]

great writeup, looking at doing this myself too, does it use alot of meth on every day driving?

id put some thread lock or a nyloc nut on the IAT sensor, dont want a bolt down one of your cylinders

Yeah, it's got blue loctite on it but I think I'll go for nyloc as I'm a bit paranoid

Not sure about usage for everyday driving yet - it's user configurable on the Aquamist unit by tweaking the gain and threshold trimmers. I'm probably going to go for something like 30-40% IDC threshold to trigger injecting. So far, this has normally been something like 3500 rpm with wot.

[TonyHayers]

The Aquamist kit is designed to maintain constant line pressure (up to 160psi) with the bypass pump, while the FAV (which is closed at rest) pulses open and closed based on the IDC signal. So, the FAV has just a 6mm pipe input from the pump line and a 4mm pipe output, to which the atomiser jet will be attached.

The FAV comes with a small bracket which I fixed to the inner bodywork with the self-tappers. If you are using the stock airbox, you probably won't have this space available, but there are a few different locations you could go for, or simply bolt it to the side of the airbox itself...



To give the potentially delicate 4mm pipe some protection in the engine bay, I fed it through some stainless braided pipe. I ordered a couple of extras from Aquamist that don't come in the kit: a 90 degree angled injector adapter and the silicon hose jet adapter. I chose to place the jet on the inside of the bend in my intake pipe, as there is more volume at that point (to allow for greater dispersion) and the shape of the space kinda matches the shape of the mist coming from the jet.







Ideally, I'd prefer the jet to be further away from the throttle body so it has chance to mix and further atomise - but there aren't a whole bunch of options that don't involve a lot of messing about. I had planned to make some more space on the intake pipe by cutting off some of the pipe from the pipercross cone filter exit and bonding on the Aluminium MAF housing so that it is one piece. This would free up approx 100mm and would mean the jet could be installed further back.

I haven't ruled out the possibility of going with direct port injection, I have a spare manifold I could prepare with the jets and Aquamist sell a nice 8-port distribution block. If I do go that way, I would retain an injector in the intake before the IAT sensor so the ECU still knows about the cool air - so 9 jets in total!

Anyway... once it's all prepared there are a couple of test procedures to prime and purge the pump and 6mm line and to check the jets are working (driving around with jet attached to windscreen to see the flow increase according to IDC!!).

I couldn't fight the temptation to go for a spin (just with pure water so no risk of spilling meth even though I hadn't done the boot setup properly - just secured everything down in the boot. My butt dyno tells me two things: (1) it feels like there is a bit more torque under injection and (2) the 5500 rpm kick is really pronounced again (remember, I don't have an airbox flap).

Next is getting the tank and pump properly setup in the boot so we can get some methanol in there

[adsgreen]

looks great.
direct port would be straightforward using the core blanking plugs. Not sure of the room and if they are the appropriate size.

[RIV]

If this does having a cleaning affect, and may help with carbon build up, surely it would be worth doing a carbon clean at the same time, and then at a later date remove inlet Manifold and check to see the results?

[cherub72]

Silas, surely it would be better to do it on an engine that's all gunked up and then check later to see how muck it's cleared off. If it clears that up then there's no chance of it not doing it on a clean set of valves. Spending a lot of money on a clean and then fitting the kit is the perfect way to do it, but if the kit does the clean then you could potentially save a few hundred to be spent on other toys

[TonyHayers]

If this does having a cleaning affect, and may help with carbon build up, surely it would be worth doing a carbon clean at the same time, and then at a later date remove inlet Manifold and check to see the results?

Yeah, it's just not as much fun

I will do a carbon clean at some point for sure and I am *very* confident that this will have a positive cleaning effect.

[TonyHayers]

Silas, surely it would be better to do it on an engine that's all gunked up and then check later to see how muck it's cleared off. If it clears that up then there's no chance of it not doing it on a clean set of valves. Spending a lot of money on a clean and then fitting the kit is the perfect way to do it, but if the kit does the clean then you could potentially save a few hundred to be spent on other toys

I don't think it's going to do anything to the already hardened on carbon tbh. Certainly not an immediate effect - at least I really hope it doesn't

[RIV]

[quoteSilas, surely it would be better to do it on an engine that's all gunked up and then check later to see how muck it's cleared off. If it clears that up then there's no chance of it not doing it on a clean set of Valves. Spending a lot of money on a clean and then fitting the kit is the perfect way to do it, but if the kit does the clean then you could potentially save a few hundred to be spent on other toys][/quote]

I can see what your saying,but on the flip side it would stand more of a chance maintaing a clean valve rather than the large build up of carbon seen on some cars, but it would be interesting to compare ether way, but the only way to know is to check the carbon build up before and after, and as you have to remove the manifold to inspect you may as well clean at the same time?

[TonyHayers]

surely it would be better to do it on an engine that's all gunked up and then check later to see how muck it's cleared off. If it clears that up then there's no chance of it not doing it on a clean set of Valves. Spending a lot of money on a clean and then fitting the kit is the perfect way to do it, but if the kit does the clean then you could potentially save a few hundred to be spent on other toys

I can see what your saying,but on the flip side it would stand more of a chance maintaing a clean valve rather than the large build up of carbon seen on some cars, but it would be interesting to compare ether way, but the only way to know is to check the carbon build up before and after, and as you have to remove the manifold to inspect you may as well clean at the same time?

Yeah, when the manifold comes off (it doesn't need to for water meth injection unless going for direct port) I'll certainly be cleaning it. I'll then take it off 10k miles or so later to look at whether it has kept it clean.

[RIV]

That makes perfect sense, lets hope it stays clean