Karmen Vortex Elemination....

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WeasyS2S

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Hey guys,
been a while since i posted...lots of work going on over here.

I have thought about the people stuck with the karmen vortex style AFMs and how it is hard to elminate that type of restriction.
So i have been thinking and talking with other people and thought of a solution that may just work in conjunction with the SMT7 to eleminate the AFM in your guys's vehicles.

I just wanted to know what you guys thought of this if i went through with it?

lets start discussion now Voice your opinions and i can see what i can do for you.

(yea my spelling sucks..i type ot fast...)
 
I would love it. Elimination of AFM means better pipings for the turbo. Most people dont know this, brand new AFM from Lexus dealer is about $750. I am looking forward for this discovery... please keep this thread alive.... i want one very bad.....

I would like to test out this ecu with my new project. I wonder what size of injectors in can control. The Emanage is only can control 376 cc and currently the split second can control up to 600 cc. What is the SMT7 Capable of?
 
Hi WeasyS2S

If you can devise a way of getting rid of the AFM then I would give you my first born, only if you wanted it.

The AFM for me is a pain. It is big, cumbersome and restrictive.

Please, please help us.

Brett
 
Last edited by a moderator:
Lextreme,
The software will be avliable shortly through my website, i have been unable to goto Perfect Powers site for a while to see if it was there due to netwrok issues at home.

Cobra,
I will see what i can do....

Does anyone know or can find out the frequency range of the KV AFM? If i can get that info then i can work from there...i saw it somewhere and just forgot where....
 
Eliminating the KV AF meter is not a difficult task.
All you need is the frequency response of the meter VS load.
You can then scale a voltage to frequency convertor (V/F) convertor to work from the voltage output of the MAP.
You also need to incorpate an air temp sensor with the same output as the one in the KV meter.
Unfortunately I don't have lost my info about the output of the KV meter.
 
Guys, have you had a close read of this article, it tells alot about the afm etc, maybe it helps.this bit probably sums it up.
Example A: If this small chamber would be plugged off or adjusted to a fully closed position; this would cause all of the filtered induction air to be sucked through the measuring chamber instead of through both the measured chamber and the small direct in chamber. If all the induction air is sucked through the measured chamber this would cause the Karman vortex sensor to measure all the induction air and report this to the TCCS for use in the BASIC FUEL CALCULATION. Closing the small chamber caused an increase in the square wave frequency for the same amount of total filtered induction air volume. The TCCS would see the air and increase the amount of fuel used in the BASIC FUEL CALCULATION.

Example B: If the smaller direct in chamber is opened up to 100 percent of its size this would allow some of the air that was forced through the large measuring chamber to bypass and go directly past the sensor. This would cause the TCCS to see less air volume and reduce the amount of fuel in the BASIC FUEL CALCULATION.

This back door air causes the electrical square wave signal produced in the large chamber by the karman Vortex sensor to slow down in frequency by a percent relative to the amount of air that sneaks into the engine through the small chamber. You might say it starts to lie to the engine or withholds information.

http://www.suprasonic.org/public_html/lexusriemer/lexusnotes.html/toyotainjection

Regards
Lambo
 
Hi Guys, found this it looks like what we need very clever gadget what do you think, simulates a Karmen Vortex or maf etc, needs carefull read further down the doc.as it says

Von Karmen Vortex Frequency output is a continuous square wave from 16Hz to 3400Hz with 1Hz resolution. Air flow meter voltage output is 0 to 5V DC with 1.221mV resolution.

The Manifold Absolute Pressure Electronic Control Unit (MAP-ECU) is designed to replace both Mass Air Flow Meter (Flap and Hot wire types) and Von Karmen Vortex Frequency based airflow meters in all ECU based automobiles. The unit does not replace the existing ECU, but simply generates the required airflow signal based on Manifold pressure and RPM. The MAP-ECU is fully programmable with a 418 Zone table controlling either Karmen Vortex Frequency (VKF) or Air Flow Meter (AFM) voltage output. In addition, the MAP-ECU has a ‘self-learn’ facility where by it can monitor either the existing VKF or AFM signal and populate the map during normal driving

www.performancemotorresearch.co.nz/ images/MAP-ECU_manual.doc
Regards
Lambo
 
Hey thanks guys this is starting to kick into high gear now :)
Lambo
"Von Karmen Vortex Frequency output is a continuous square wave from 16Hz to 3400Hz with 1Hz resolution. Air flow meter voltage output is 0 to 5V DC with 1.221mV resolution."
That is something i really needed!
 
KDog said:
Eliminating the KV AF meter is not a difficult task.
All you need is the frequency response of the meter VS load.
You can then scale a voltage to frequency convertor (V/F) convertor to work from the voltage output of the MAP.
You also need to incorpate an air temp sensor with the same output as the one in the KV meter.
Unfortunately I don't have lost my info about the output of the KV meter.
Click to expand...
Yes it is not that hard i know that, but everyone says the same thing yet nobody does anything.
I am no electronics engineer but i am learning how to do these kinds of things as they interest me. I have a group of people that are starting ot help me out with this as my goal is to provide a cost effective solution for the KV users .
 
Lambo,

Re-read what the device can do.

It can provide EITHER Frequency OR a voltage signal. Not BOTH at the same time.

This item was raised by (I think) Cobra a couple of months ago and the downfall is you would need two units to provide the output our ECU uses.

Our ECU senses frequency and voltage, plus air temp so it won't fill the bill.
 
Zuffen said:
Lambo,

Re-read what the device can do.

It can provide EITHER Frequency OR a voltage signal. Not BOTH at the same time.

This item was raised by (I think) Cobra a couple of months ago and the downfall is you would need two units to provide the output our ECU uses.

Our ECU senses frequency and voltage, plus air temp so it won't fill the bill.
Click to expand...
From what i gather the ECU takes in the frequency as the airflow and the voltage is the air temp...the SMT7 will take a reading via the map sensor for 0-5v analog signal and send it ot the SMT7 which will then send the corrisponding voltage to the conversion unit then to the ECU...
The SMT7 will also provide the intake air temp to the ecu as well....
 
WeasyS2S,
Short of time I am. If you need help then let me know. I could proably tell you what to do and then you could actually do it and provide a working solution. Many V/F convertors out there. You could probably get away with a one chip solution if you wanted. Of course you can always make a V/F convertor out of opamps as well if you really wanted. The Art of Electronics by Horowitz and Hill will teach you more than enough to complete this task. It may even have an exact solution in the book!!

The A/F meter part is only a frequency measurement.
THe air temp is a voltage output. It shouldn't be too hard to find an air temp sensor which has the same output as the one in the KV AF meter.
 
Hi Zuffen, I have sent an email to the manufacturer and asked him to comment, have given him this address so we may yet get an answer. I agree the Temp sensor output voltage should not be a major but as far as i can determine from the Riemer artilcle " The variable frequency square wave signal is how the TCCS engine control computer knows what volume of air is entering into the engine. The square wave signal is output by the air meters electronics to the TCCS ECU. This signal is a five volt signal switching on and off faster and faster as the volume of air passing through the air flow meter is",
i think the gap between the on and off is the frequency in hz and so is really just one signal , ie a constant 5 volts at ever changing time periods, that the ecu understands
Best regards
Lambo
 
I've looked at this in the past, and there is a fair bit more to it than just "map voltage is proportional to MAF frequency". Busy at the moment, but I'll try and write a quick explanation later or at work tomorrow

edit:

OK I got some time. I was looking at this for a buddy on a little Nissan motor.. or a little Toyota motor in a little Nissan, can't remember. He had slapped on a turbo and discovered the (approx) 50mm AFM was a restriction - big surprise. He constructed the manometer on Autospeed, and measured a huge pressure drop across it - from memory it was over 1psi!

Anyway, we plumbed in a MAP, disabled boost, and I watched the output of it and the output of the AFM on his Fluke. Unfortunately it didn't have much memory so I couldn't capture enough to really form a solution. But basically, we idled along at low RPM with the throttle almost shut. Then stomped on it and watched the output. The picture is what I remember happening (though it has been a while!). Basically, you stomp on it, the pressure goes almost straight to atmo. The AFM however shows the amount of air flowing past it.. which of course goes up with rpm. The MAP looked more like TPS crossed with volumetric efficiency. The AFM frequency may have been more exponentional or something.. can't remember.

Basically the conclusion I came to was that we would need to integrate the MAP signal with respect to RPM.. or maybe with respect to dRPM/dT. Can't remember. But it proved too complex to solve easily, and was a definite case for a basic map and then some tuning knobs. Shortly after that we discovered that somebody made a suitable product.. either HKS or APEXi.. called the VPC if I remember correctly. BLOODY EXPENSIVE but he found a second hand one for a few hundred bucks and installed it.

My thoughts: I would love to finish this project, but it would require a LOT of work.

Con: If you upgrade to 2x stock injectors, you want your AFM/MAP to basically tell the ECU there is 0.5x as much air going in the engine. This does screw you over two ways though. You lose a bunch of resolution on your off boost mapping. You are only using at most half as many maps! They'll probably be the conservative ignition ones etc too. Perhaps a better solution would be some kind of injector-pulse-halver? Dunno.. I read some literature saying one of the units out there does this? eManage? Dunno... You get the problem here that the max duration is 50%, so I think they play with the AFM signal as well. Very complex.

Con: If you upgrade to 2x stock injectors and halve the AFM signal, you lose the backup functionality the TPS provides.. that is, if I walk out to my car and pull the AFM off, the car will go into limp mode and overfuel, to get me home. It runs off a TPS map. So if your new MAP->AFM thing dies, or a wire gets cut, or the ECU just decides it doesn't have a proper signal, it goes back to the TPS map. This then floods the hell out of your engine (stock 1x+ pulses on 2x injectors!) and you go nowhere.

An alternative which would overcome some of the problems, is the so-called dual MAF. I've seen people run two MAFs with simple electronics to "add" the signals (which would not be hard with the frequency based AFM we have, if they are linear.. or just map if not). I've also heard of others running bypass pipes and "mapping" with SAFCs etc...

I don't really like that one though. I'd like to ditch the AFM altogether. It takes up space!!! It would take a lot of work though.. maybe one day.
 
I've heard of the Dual MAF on Nissans, many cars really, but I believe that would be much easier to comprehend, and wouldn't require the intense calibration of a new chip/sensor.
 
Hi Guys, this is the reply i have back from Peter at http://www.performancemotorresearch.co.nz/ i sent him a circuit on the afm and also the temporature values from the AFM spec, below is his reply.Quote"
Hi Graeme,
This air flow meter is pretty simple, you only need one MAP-ECU to replace it. You do not even have to use the analogue Baro output voltage wire.

The MAP-ECU outputs a frequency (5 volt square wave). Frequency is measured in Hz, which is a function of time between pulses. If you have a 30Hz square wave, that means you get 30 full cycles per second. 3400Hz means 3400 full cycles per second, pretty simple.

The MAP-ECU has a 374 zone table where you can enter values in Hz (16-3400).
The bigger the number, the more air the Toyota ECU thinks is going in so more fuel is injected. The relationship is not linear which is why there is a table (just like the fuel table in the Toyota ECU).

I think your friends on the forum have got confused thinking the air temp sensor is a generated voltage, it is not, it is just a resistor that varies according to temperature. The datasheet confirms the sensor we provide is the current resistance. We provide a 2K2 air temp sensor that you wire into the AFM loom so the Toyota computer behaves normally. As you can see from the ECU diagram you sent me, the air temp sensor is electrically independent of the actual air flow meter.

You should be able to get started with one of the Karmen Vortex Frequency tables available on the www.mapecu.com website for Supra's.

The wiring would be as follows:

Red - +12V ignition
2 x Black - Ground on ECU
VKF Output (Blue) - KS
RPM Signal (White) - One of the Igniter signals TPS Input (Brown) - VTA1
O2 Input (Yellow) - OXL2 or OXR2 (Optional)

"hope this helps the cause , Peter is in New Zealand so if you have any more Questions i will give him a phone call.

Best Regards
Lambo
 
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