hey guys,
I'm trying to work out if it would be possible to run a water/meth injection controller using the MAF signal as referencing.

Anyone know what the voltage range of our MAFs are? For example apparently most jap sensors read from roughly 0-5V.

Any other relevent info also appreciated, e.g part number, what other cars share the same sensor etc.

Cheers.

http://www.aussiemagna.com/forums/showthread.php?t=58623

Not sure if my thread here helps you somehow...

Pretty sure its 0-0.5v it came up on the Datascan just cant remember the exact figure as it moves faster then a cat on fire

Karmen vortex sensors are frequency based.

It is a 0-5v square wave output, ranging from 33hz at idle to 4000hz.

Is there anything else you would like to know?

would it not be more appropriate to use the throttle position sensor for a signal (say when over 40percent throttle?)

jsut an idea

It would work, but remember throttle position isn't proportional to load. You can be at 2000rpm and 30% throttle will be 100KPA MAP pressure, so full load.

Higher in the rpm, 30% would only be 50KPA so half load or there abouts.

It would work but not as sweet as a frequency trigger would, but I would just use TPS yeah.

Karmen vortex sensors are frequency based.

It is a 0-5v square wave output, ranging from 33hz at idle to 4000hz.

Is there anything else you would like to know?

Excuse my lack of electronics knowledge, but does that mean the sensor reads 0 at low airflow, and then the voltage increases to 5v as airflow goes up?

Because the controller I am looking at requires this to work properly, there is no mention of frequency, just voltage.

Or does the signal just increase in frequency as airflow increases, but the voltage stays the same, or does not increase in proportion to airflow?

my S-AFC shows a consistan rise in voltage as air flow increases, with idle its around 400mV and goes right up to 4.9V at 99%throttle

would it not be more appropriate to use the throttle position sensor for a signal (say when over 40percent throttle?)

jsut an idea

i know what you saying... like when a granny struggles up a hill in 4th at 40km/h but instead of downshifting they just apply more throttle until they are flat footing (100%) but still only doing 40km/h at about 1700rpm

More the reason why i would use the TPS (only if it was variable flow water injection) is that water/meth injectios is really going to help prevent detonation which is likely to occur in the above scenario

anyways, either or will get the job done

Could always look at using the MAP sensor or the Intake temp probe for the WI,

Excuse my lack of electronics knowledge, but does that mean the sensor reads 0 at low airflow, and then the voltage increases to 5v as airflow goes up?

Because the controller I am looking at requires this to work properly, there is no mention of frequency, just voltage.

Or does the signal just increase in frequency as airflow increases, but the voltage stays the same, or does not increase in proportion to airflow?


No - it means it uses 0-5v as a digital (or binary) output. 0v = 0, 5v = 1. The frequency refers to how many times the signal changes state (0-1, 1-0). The frequency range of 33-4000hz is converted to an airflow measurement by the ECU (probably 0-4000hz actually - but it reads approx 33hz at idle).

There would be a parameter in the ECU for the MAF input based on the frequency. For the sake of simplifying it - 0hz (or zero cycles per second) might equal 0L/s of air flow, and 4000hz (4000 cycles per second) equals 4000L/s of air flow (assuming 4000L/s is the maximum the sensor can measure).

The device you are talking about sounds like it uses an analogue 0-5V signal (as opposed to a digital one) - where 0v = 0L/s and 5v = 4000L/s (for argument sake).

Make sense??

my S-AFC shows a consistan rise in voltage as air flow increases, with idle its around 400mV and goes right up to 4.9V at 99%throttle

Is that signal coming from the TPS or the MAF?? If it comes from the MAF - then it contradicts roy's first post in this thread. If it comes from the TPS - well yeah, just refer to his 2nd post..... guy seems to know what he's on about.

Is that signal coming from the TPS or the MAF?? If it comes from the MAF - then it contradicts roy's first post in this thread. If it comes from the TPS - well yeah, just refer to his 2nd post..... guy seems to know what he's on about.

If his MAF reads 0-5 voltage as airflow increases, then he isn't driving a 3rd gen lol

I have done extensive work on the Karmen Vortex MAF's and am currently working on a basic intercepter chip to increase fuel econ and power by faking a signal to the ECU.

RPM Frequency(Hz)
Idle 33
1500 61
2000 80
2500 100

It is like Blackbear said, 5v square wave signal. The waves are always 5v tall and 0v when off, and the frequency increases when there is more air. It is a very simple sensor, which runs from the Karmen Vortex principals of fluid dynamics. Wiki has a good read on it.

If you have a frequency digital multimeter, you can test it out yourself. This is how the airflow meters are calibrated at the factory. A known amount of air is flow through it, and the adjustment screw on the underside of the MAF is wound in or out to bypass or allow flow past the sensor until the exact frequency is met. Adjusting this sealed screw is a crude way to increase power btw ;)

This is a frequency table vs RPM I have made just for a document I am putting together regarding the intercepter chip.

Looks like I can't use this kit/controller then :(

I will double check, but yes I believe it works on an analogue signal that increses in voltage as air flow increases. The controller can also reference off boost level, but that's a very crude way of doing it - pretty much injecting the same quantity of water/meth for most of the revrange, regardless of load.

Looks like I may be going with my original but pricier plan - A haltech intercepter will be used, using a mapped injector setup to deliver the meth/water. The haltech will also carry a set of maps for when the WI is functioning. If/when the WI setup runs empty or isn't functioning, the haltech will switch over to the trusty old SMT6 from Sprintex.

Yep, I will be running 2 piggybacks - The haltech will control the water/meth and carry the "power" tune, the SMT6 with my current edited Sprintex tune will be retained as a safeguard. A fluid level of pressure switch will be used to trigger the map-switch in the event the water/meth aint running.

haha thanks for point that out ROY... i went and had another look and what do you know haha because the sensors are only listed as 1,2,3 it turns out the one i was looking at was the TPS (hence what i said above) but when i adjust the measurement table and view the other sensors i can get the MAP sensor in hz, which is pretty much a stable 32hz at idle

sorry for the confusion guys

Chisholm, i believe jaycar have a frequency to analogue converter. Pop in to a store and ask one of the techies about it.

It will do exactly what you want.

There are cheapish stand alone ECU's with the capabilities to do what you are doing. E6 series, Wolf, Link all have a pwm per output.

Another option would be to use the injector feed perhaps.

I've found that there is a version of the controller I'm looking at that works with evos.

Now from memory evos use the same or a similar karmen Vortex MAF as we do. Can anyone here comfirm/disprove this? Do they use the same frequency range?


Chisholm, i believe jaycar have a frequency to analogue converter. Pop in to a store and ask one of the techies about it.

It will do exactly what you want.

There are cheapish stand alone ECU's with the capabilities to do what you are doing. E6 series, Wolf, Link all have a pwm per output.

Another option would be to use the injector feed perhaps.

Interesting, I will have a look into this, cheers :)

I'd prefer to stay away from standalones for a number of reasons.

Yep, replacing the Sprintex 7th injector with a water/meth nozzle/injector is an option, however I'm fairly sure I'd need to upsize the 6 factory injectors if I were to do this.

I know the 7th injector is a controversial issue around her, but to be honest I am satisfied the setup works fine, and there is nothing to be gained by removing it.

Looks like I can't use this kit/controller then :(
Out of curiosity, are you looking at the Boost Cooler water/meth injection system?

Out of curiosity, are you looking at the Boost Cooler water/meth injection system?

Correct :)

Well I've found out there is a version of the controller that works with our karmen Vortex sensor, but the supplier is out of stock for 4-5 weeks,,then add another ~2 weeks for it to get here..back to playing the waiting game :(

Well I've found out there is a version of the controller that works with our karmen Vortex sensor, but the supplier is out of stock for 4-5 weeks,,then add another ~2 weeks for it to get here..back to playing the waiting game :(
So it will work the same way? Water injection will increase as the MAF voltage increases (due to increased air volume)? How much was this kit if you don't mind me asking? You can PM me if you want.

I wonder how much the timing can be advanced for the 2nd map on the SMT6 piggy. How much power do you expect to gain between the 2 maps?

So it will work the same way? Water injection will increase as the MAF voltage increases (due to increased air volume)? How much was this kit if you don't mind me asking? You can PM me if you want.

I wonder how much the timing can be advanced for the 2nd map on the SMT6 piggy. How much power do you expect to gain between the 2 maps?

Have a look here:

http://www.full-throttle.com.au/Engine/Boost%20Cooler.htm

I got offered a discount on the stage2 kit, $600 (although it seems to be listed as $600 now anyway). Then add a bit more depending on the accessories you get, e.g larger resoviour, fluid level indicator etc.

One place in sydney who has done a bunch of them (Insight motorsport) quoted me $500 for fitting.

I've been told by a few different sources to expect a 10-20% gain in wheel kw, depending on how agressive the new tune is etc. Also intake temps will be much more consistent.

The gains come from being able to run more timing, and also run a leaner AFR. Also obviously intake air temps will be cooler, and combustion slower and cooler.

Given our factory pistons aren't exactly bulletproof, I'm inclined to continue with 12:1@WOT for peace of mind, but I'll look into this more. Not all that much power to be gained by running a bit leaner anyway.

I will check with my tuner about this, but I think we will leave the "safe" map from Sprintex alone, and simply edit the "power/cool" map. The safe map will probably rarely/never be used, it's just there incase the WI runs out/****s up.

the reason 12:1afrs are safe (when boosted, a little leaner when NA is still safe) is the extra fuel is needed to keep combustion temps lower, which helps keep the next intake charge cooler and so on, its just safe.

If you are running a decent water injection system (like the one in the link) you could go quite lean in the search of power and response, as the water can be substituted for the fuel, so its quite possible to have combustion temps as cool as 12:1 when running as high as 13.5:1 as long as the water injection system and tune is up to it.

when a family friend of mine used to work as a tuner, he had his own 4AGZE with water injection kit running 14.0:1 upto around the 3200rom mark where it levelled out to 13.5:1 at 6000rpm. He said he had a 15kw gain over his petrol only tune but picked up 80kms extra per tank haha bar the use of several litres of water.

If you got the funds and are supercharged, in this countries weather you couldnt go wrong.

the reason 12:1afrs are safe (when boosted, a little leaner when NA is still safe) is the extra fuel is needed to keep combustion temps lower, which helps keep the next intake charge cooler and so on, its just safe.

If you are running a decent water injection system (like the one in the link) you could go quite lean in the search of power and response, as the water can be substituted for the fuel, so its quite possible to have combustion temps as cool as 12:1 when running as high as 13.5:1 as long as the water injection system and tune is up to it.

when a family friend of mine used to work as a tuner, he had his own 4AGZE with water injection kit running 14.0:1 upto around the 3200rom mark where it levelled out to 13.5:1 at 6000rpm. He said he had a 15kw gain over his petrol only tune but picked up 80kms extra per tank haha bar the use of several litres of water.

If you got the funds and are supercharged, in this countries weather you couldnt go wrong.

Water is not a substitute for fuel, but I agree with that you are getting at; The extra cylinder cooling from the water/meth should mean you don't need to run a richer-than-optimal AFR to provide cooling, different motors respond to and "like" different conditions.

The example you give is an interesting and believable scenario, however it may not have much relevence to my setup.

For example 4AGZE pistons are much better suited to boost than the magna factory pistons. Also different motors respond to different things. For example some motors may gain very little power from being leaned out, but respond well to ignition advance. A good example of this is the Toyota 2JZ motor - while it seems it can survive running at 13:1@WOT just fine, you are still generally better off leaving it at 12:1 and being able to safely run a little more ignition timing.

In contrast, apparently ferrari road car engines run something like 13.5:1@WOT from the factory, which is downright dangerous for most motors. There are many factors which determine what a motor "likes", such as combustion chamber/piston shape, flow characteristics of the heads etc.

I suspect working out what's good for this motor will be a trial-and-eror process, and up to my tuner what he wants to do, unless I come across some good information.

cant agree more on the individual engines require individual routes to tuning, the reason ol'mate in the rolla was so inclined to see what he could do was because the enigne was stock and a replacement was only a wreckers visit away ahah and yes the engines in the supercharged rolla have the benefit of being designed around being boosted.

I wasnt suggesting water be used as fuel, i was saying that just a water (no meth) setup benefits the engine, by proivding cooling to the inlet charge (not as much as water/meth) but cools down the combustion to allow a leaner afr (the leaner, the more bang you get) coupled with heat produced by running close to stoich, nigh on no road going car can handle leaner than 13.5:1 due to temps of combustion and risk of detonation (barring some examples) melting pistons, hot spots on older engines and so on and so forth

running water/meth you are adding another fuel source, so petrol can be wound back, as its substitued by the alcohol (a slower burning more detonation resisntant fuel). So, without a tune you car will be running richer then it was but it will be a very safe. With just water the AFRs wont change very much at all, but you still get the detonation protection, and both scenarios will see a power increase due to slightly higher compression from the added vapours to the inlet charge.

Both setups will be able to take a lot more igntion timing, and the water/meth setup will allow for the greatest safenet and power gain (probably your reasons for going this way CHISHOLM)

ANyways id really love to see some results from a magna. keep us all posted.

Hey Chisolm any updates on this WI kit?

has anyone thought about just running a hobbs pressure switch??

http://www.fdrive.com.au/products/05/pressurep.php

seeing as the water injection would be only needed at certain boost levels i think this could be another option to look into as well as the setup you have already planned.

Hey Chisolm any updates on this WI kit?

Ill answer that on Andys behalf, im sure he wont mind.

He is still waiting for the kit to be instock in the US, still looking at over a month away, plus install and tunning time.

FYI folks, I am looking at running the same kit on my Evo