Intercooler water sprayer idea...

[Poita]

Ok I read through autospeed/silicon chip'a article on their intelligent intercooler water sprayer. Nice idea, works well but it can be improved.
http://www.autospeed.com/cms/A_107797/article.html

The temp sensor they use is not linear and is an analoge output so will be affected by noise (electrical) if the cables have to travel all the way back to the dash, there will also be a voltage drop.

The intercooler temperature is shown on a series of LEDs yellow = cold, green = good, red = hot. The thermistor is not linear, so as the cooler heats up, it will take a bigger rise in temp to move to the next LED than further down the scale where it will move quite quickly.

SO...

I am going to use a calibrated digital output linear temperature sensor. So it will not suffer from noise interference or voltage drop hassles.
I am also going to run it all from a micro rather than discreet ICs. This enables the use of a LCD display instead of the LEDs and I can display the temperature of the cooler and the temp threshold in degC which is a lot more useful.
Will be converting to SMD components as well so hopefully keep the size down.

But some questions:

To sense engine load they use the air flow meter output to the ECU. Now I haven't had a play with the Legnum's electrical system yet so was hoping someone could help.

1. What is the voltage range of the air flow sensor from 'no load -> full load' ? Is it 0-12V or 0-5V?? Also where is this cable? I don't have a wiring diagram
2. Is there a better way to sense the engine load?
3. I am happy to make more if this works out so any suggestions of any other additions/improvements while I am in the design phase?

Don't expect it to happen tomorrow It will be fitted around my spare time at work, but shouldn't be overly difficult!

Cheers
Pete

 

[TME_Steve]

Hey Pete,

You and me have been thinking along the same lines.... I have been thinking of an intercooler spray kit also (maybe injection) I was initially thinking of using the ECU to control the spray but that necessitates adding some sensors and I think it's too far off in reality. I haven't read the auto speed article for ages but I thought they used injector duty cycle to sense power (you could use pulsewidth to determine torque). It would be good enough for a spray but then the MAF signal would also be fine. I think it's 0-5V but I'll try to remember to check tonight....

 

[lathiat]

May be worth looking at aqua mist for at least some parts, or, if you give up on your own system, the whole kit
http://www.aquamist.co.uk/

 

[Macca]

I was thinking of doing something like this when I finally got around to upgrading my intercooler. Will be keen to watch how you go.

 

[Poita]

May be worth looking at aqua mist for at least some parts, or, if you give up on your own system, the whole kit
http://www.aquamist.co.uk/

They seem more focused (from what I can see) on the water injection... something I am not interested in. I just want the intercooler spray system.

And they look like they would be very pricey... I design electronics for a job, so no way would I pay the sort of figures they would be asking for a kit that I would only use a small portion of and which I could design and build for my self much cheaper!

But thanks for the suggestion!

Edit: but yes I will look at their mist sprayers etc.

 

[Macca]

Make up a kit an sell it on OZVR4 I'd probably buy one if they weren't too expensive.

 

[naughtika]

Poita, I didn't mean to Hi-jack your thread, I've just re-read your first post, and you mentioned intercepting voltage from the MAF sensor? I'm just worried that if we intercept/fiddle with the MAF sensor, it might give off wrong readings to the ECU, which in the end might cause dramas rather than gains..

 

[snickells]

Perhaps you could pick up on one of the OBDII outputs to measure engine load. It wouldnt screw with the ECU measuring any of the signal inputs.

 

[Poita]

If the MAF output is max 5V it would just go straight into an ADC pin on a mico so wouldnt be fiddling with the actual signal, just tapping in and reading it.
The OBD sounds interesting as long as there isn't any special coms protocol.
Keep the ideas coming! Never done to much with a cars electrical system (apart from audio) so suggestions are welcome!

 

[hozza]

what about through a boost gauge. boost comes on with engine load should be able to set the spray with a certain amount of boost?

 

[TME_Steve]

a map sensor is ok if you want load (torque) but the maf will give an indication of airflow (power), injectors give you both, pulse width is proportional enough to torque for this exercise, duty cycle correlates to power....

 

[TME_Steve]

Hmmm I thought I had a maf pinout diagram here, doesn't seem like I do, I'll have a better look tomorrow.... And it's a voltage output from the maf so reading the voltage should be ok, as long as we dont change the voltage. I still like injectors though.... Injectors can be used on any car, whether it use maf or map or a combination.

 

[Poita]

Hmmm I like your thinking... Adds a little more complexity but measuring the pulse width should be easy enough using an interrupt and timer... Any idea what voltage level that is? I am assuming 5V if coming from the ECU.

 

[naughtika]

how about a pressure triggered switch? my dad used it for the buses (doors, air suspension, air brakes) same concept as the ayc pressure switch,

when it gets to a certain pressure (say 10psi?), it is triggered.. that way there's no fiddling with the MAF sensor's harness..

also maybe a temperature triggered switch, that way when it gets to a certain temp, it is activated.. I don't think they need the extra electronics, just a bit of relays and wires connected to the waterpump..

here's a temp triggered switch/relay

http://www.maplin.co.uk/temperature-activated-switch-kit-220003

and pressure triggered switch/relay
http://www.smcaus.com.au/catalogue/product/625/302/is1000.html

switch listed above (SMC) is what my dad uses for installs, max operating pressure is at 0.7MPa (approx. 101psi lol)

hhmm now that I think about it.. I think he's got 1 or 2 in the shed..

 

[Poita]

I don't want to use just switches... that provides no flexibility or adjustment just on or off... so voltage or frequency levels into a ADC on a micro are preferred.

From the Autospeed article:
"The load input for the Intercooler Water Spray Controller can be taken from the airflow meter or MAP sensor outputs, or where these are not available, from the throttle position sensor. This can be done at the ECU or the sensor itself. Use the workshop manual wiring diagram to find the load sensor output and then use your multimeter to check that it’s correct. The measured voltage on the load sensor output should rise with engine load. (Some cars use a frequency output on the airflow meter – in that case, use the throttle position sensor output.) "

The throttle sensor idea is interesting but wouldn't that just sense revs? In this case it wouldn't be a real indication of load as such.

 

[Poita]

Hmmm I thought I had a maf pinout diagram here, doesn't seem like I do, I'll have a better look tomorrow.... And it's a voltage output from the maf so reading the voltage should be ok, as long as we dont change the voltage. I still like injectors though.... Injectors can be used on any car, whether it use maf or map or a combination.

Would the PWM going to the injectors be controlling how many times per second they squirt fuel, or how much fuel they are squirting?
The former wouldn't be any use, but the later would be a good indication of load I think...

 

[TME_Steve]

How long they are open for.... Frequency of the injector pulse is based on rpm which is easy to read so you can work out a power relationship from the two. Sounds like you are wanting torque which you could just use pulse width of the injector or m.a.p. Personally I would use power, so a combination of frequency and pulse width ( ie duty cycle - % of time squirting fuel).

 

[Poita]

Ok been doing some more thinking about this frequncy and PWM of the injector signal and it sounds like the best option.

Now probably a stupid question, but does anyone know the freq and PWM ranges? I am trying to get out of measuring them while driving along

It's just that I am going to need to drop the signal to 0-5V of the ADC input on the micro and am toying around with different ideas, but if the frequency is fairly high then I may need to take that into consideration.

Edit: Ok I didn't think hard enough... frequency is proportional to rpm. Now if I am reading a single injector and the rpm range is 0-6000rpm then the frequency will be 0-6000Hz.
Rang an auto electrician friend and the duty cycle is typically 2-3ms at idle and up to 40ms at full load (car dependent but it gives some figures).
It's 12V and the injector is switched to 0V when it is activated.

Edit 2: The injector frequency would be half of the RPM right?? As 1st RPM is firing stroke (injector on) and 2nd is exhaust stroke (injector off). So the injector frequency would be RPM/2...

 

[Guest]

Surely our ecu's can be tuned in a similar way to that of evo's? Evo's ecu's can be reflashed to include automatic water spray (utilising their oem waterspray setup) at certain rpm levels, or boost readings, or even at a certain rpm/boost reading in each gear...

I've also thought about using a water spray set up from an evo or sti and having it wired in, albeit to a on/off switch. It surely can't & shouldn't be that hard to do it that way...

*edit - also, have a read of this thread...some handy info from someone who's already done a water spray set up.

http://ozvr4.com/forums/showthread.php?8832-Water-Injection-and-IC-water-spray-system-for-Legnum

 

[Poita]

jdm_vr4: I have no idea about the capabilities of our ECUs... I haven't read anywhere about a factory water spray controller in them and as far as I konw we don't have any oem setup.

And yes I have read that thread from start to finish