ping ping BOOM pst pst pst....

Da** detonation. We know that detonation and pinging is the rotary killer. I experienced once too often! I saw my melted side seals, collapsed rotor, and blown apex seals.(over boost augmented the damage)

In my absence due work, i was thinking constantly.I was taking this in account:


Engine knock sensor required
I am looking for a voltage amplifier. The input will be from zero to 250mV and output up to 5V DC. It is needed to convert the voltage signal from engine knock sensors to a higher voltage so the EMU can read the signal (up to 5V DC).
Will an audio amplifier with an AC-DC converter do?
(J. C., via email).
The engine knock sensor described in the April 1996 issue of SILICON CHIP has the essential ingredients you require. These are the amplifier (IC1a with adjustable gain from 2 to around 200) and a DC converter comprising diode D1, a 1μF capacitor and a 1MΩ resistor.

Now through the AEM ECU i gathered that the system retards 3 degs per 1volt generated output. If the auxin 1 was used to retard accordingly?

Am i making sense? HKS do a knock monitor.... but why go for an HKS Monitor when Wolf can be configured to use the retard capability.

I was in touch with J&S safe gaurd. Their system is marvelous, but with one massive set back: only the leading spark channel is retarded, to a maximum of 20degs.DOH! you might retard the leading more then the trailing and miss fire the engine and break it up anyways! Jason at RX7 store also recommended against the safegaurd, i guess due to this setback. I suggested to john at J&S to make a two channel system where both leading and trailing are retarded linearly. however nothing materialised.

So had we to use the stock REW mic in the housing, amplify the voltage linearly to a max of 4.75volts, and thus use it as an aux input, and thus modify the ignition table in accordance to knock?

Hope i am making sense....

Anyone who has any feed back, comment, ideas or anything do let me know.

Finally I am back to bother you guys with my posts

My fd has been doweled, street ported to the max, (up to the water jackets,on pri and sec) ACT Streem 6 Puck, AVCR, x4 850cc injectors for breaking in.ported oil pump and oil passages, tri rotor main bearings...oh yes and powercoated all the aluminium components gloss black! I aught to pick them up today from the shop, god only knows the financial damage..next week i will have her 'ronin' again!

Cheers
George

 

I have used the Mazda Knock detector before. I built a lilttle circuit that monitored the output from the detector. It was crude but it worked ok.
Knock detector 101.
1.. the output of the Mazda Knock detector is a series of pulses each time it hears detonation or someone hitting the engine with a Hammer ( boiner owner maybe!!)
2 Just because you get a Pulse doesn't mean that you detonation, at idle the detector often is sending out pulses.
3 Most detector use a window type detector that is if they receive say 10 pulses in1/4 sec then you have Detonation. If you have 20 pulses you have servier detonation. Almost all detectors have a digital output, that is if you have detonation you have 5 Volts at the output. No detonation you have ground.
4 How to interface a Knock detector to a Wolf. Well I would use a small CPU to count the pulses and then output a variable voltage proportional to the knock. Now feed this back into one of the Wolf inputs and use it like a trimming Pot. You may be able to reduce the timing depending on the Voltage. Now the Wolf looks after split so no trailing ignition issues either!!!

Down side HARDWARE REQUIRED
UP side you can tune to the very edge!! == More power or regular gas

Take your pick.

Michael Smith

 

Here's some info on a circuit for Megasquirt:



and the link:

http://megasquirt.sourceforge.net/extra/knock.html

Maybe I should add this to my setup--got me thinking about it?

Scott

 

The Mazda knock unit has all that inside already, but the output is inverted. Thanks for the megasquirt link. I often visit the Megasqirt section for ideas you blokes ROCK!!! I wouldn't trade my Wolf though I like it. The ideas thay you Guys and Girls come out with are outstanding.
Michael Smith

 

Hehe that's what its all about. Well, this setup should not cost more than 50USD. The compnenets are easily access able. I will Take the Squirt diag to my electronic shop.... and see what i can come up with.....

Well, I would sure consider knock detection!!! It's a must, good how good on the tuning, this can save an engine. I would go on the conservative side.

Michael, what do you mean with the mazda knock unit? we still need to process the pulse no? I mean, the screw on attachment (mic) on the front rotor housing i thought was just a mic, and converting db into mvolts.... right? Define the knock unit please....

Thanks

George

 

Under the dash there is a CPU that converts the signal from the pickup on the rotor housing to a digiatl one. All we need is a small PICAXE to count the pulses and then output a variable voltage for the Wolf.

Michael Smith

 

hmmm....this get me thinking. I will try locate this CPU. Was never aware of it. My problem in locating it is that my FD is a Jap import, and everything is in Japanese!!!!
its a right hand drive unit. so i figure its location is somewhere under the steering colomn no? Perhaps am asking too much, but, could u describr this unit? I have to make my way in alot of japanese iconographs.... and hehe they mean nothing to me!

 

one sec.... we are talking on FDs right??I know the FC have it! So i guess i might need to find a CPU module too after all!DOH!

My electronic shop is giving me the availabiltiy and price s of the mega squirt components.... will keep you posted.

I guess i might be needing a FC unit then right?

George

 

This is the FD setup from the factory manual.........

 

Mine is a FC model and it is Right hand drive. The Knock cpu was on the left above the kick board. Looks like the CPU is in your old ECU maybe a FC controller will do the job!
Regards
Michael Smith

 

i located a unit here in malta...... would you have any wiring diagram of it? or a pin out sheet? to see the stock parameters.....

 

query...would anyone know if the MSD unit or J&S knock monitor have a 0-5volt output?.....it would save a million probs no?

 

should get that FC unit today...... Anyone got a hard wire diagram of it?
Michael, i am not that electronically inclined, so how do i go about the picaxe you mentioned earlier?

Thanks

George

 

George I will get a diagram for you it will take a few days.

Michael Smith

 

Thanks Michael!!!

George

 

Catch this it is from the rx7 update to the workshop manual.

Regards
Michael Smith

 

Happy Thanksgiving!

A new group buy from Wolf USA is in the works!! Send a PM to the
owner of the forum and tell him to get it up!

I have been playing with knock boxes for awhile now. J&S is great,
just make sure you set it up so it retards leading 5 degrees and your
trailing stays after that. In other words split must be more than 5.

All Turbo rotory cars had a box somewhere. They could not determine that
is that "REAL" knock is very hard to seperate from "Ghost" knock.
Knock that may cause a mechanical failure should be detected before
it is audible to the human ear. Unfortunetly the voltage created by the
pizeo crystal in the sensor is very small and can somtimes be confused
with exhaust ping (on decell), stiff suspension components, solid mounts
on engine or trans etc.
How to make the box smart enough to translate the sensors input in the
high performance world is very different than the OEM daily driver.

I noticed that the wiring diagram that Michael posted shows the knock box
output is from 900rpm - 4000rpm, or that the stock ECU doesn't look at it
over 4000rpm. I will test the output of the box soon. Either way I am sure
Mazda realized that after 4000rpm (as we all know) the caracteristics of the
turbo charged rotary get a bit louder. The tech stuff back then wasn't up to it.

Being able to configure the input on the Wolf to disregard the signal,if the signal
is to low, is good. Keep in mind that the signal must also be adjustable so when
it is "high" the Wolf ECU sees it and the signal is really caused by knock!!

Using an output from the Wolf to only turn on the knock box above certain load
values, tps values, etc is a good idea. Below those values (decel) the box will
be off and will not retard timing.

A really, really good ignition system is available from Smartfire. It senses the
ion/plasma flow coming from the spark plugs and determines if knock is going
to occur before it does!! It sells for about $22,000.00. I say we all chip in and
start a COOP and get one.

Chris Greene
Wolf EMS USA
916 289 0488

 

22,000 USD???? wow..... you sure there is no extra zero? D*** as much as my vehicle cost price!!!!

am going through michaels data sheet....

Thanks for the inputs..... working on an amplifier at the moment..... and a voltage convertor from db to volts....

 

Picaxe micro controllers.
Here is a starting point http://www.rev-ed.co.uk/picaxe/software.htm they are basically a one chip computer that can be programmed in basic or with flowcharts. They are worth about $20 au and a program cable you can make no sweat. Just plug it into you serial port on your home computer after writng the flowchart or program in basic and download it. Place it in circuit and you are off!! You will need some soldering skills and a small soldering iron.

Regards
Michael Smith

 

hmmmmm..... interesting...... going through the site now...

 

Dig Dig Dig here is a article from silicon Chip magazine under Knock on my Wolf support site.
http://www.angelfire.com/droid/wolf3dems/
My site is now Full I can't fit any more data I have a better copy zipped up for those who would like it emailed to them

This is a linier output so the more knock the a higher voltage is put out which is ideal for the Wolf.

Cheers
Michael Smith

 

there was a thread in the haltech section recently along with the 2nd gen sectio where as someone built a circut that hookes up to a stock knock sensor and output's a 0-5v signal depending on sevarity? not sure


Just remember, if your engines knocking, pulling timming may stop the knock but egt's might go nuts

 

yep..... so add fuel as you retard..... cools things down!

 

You know Michael, I do have space with your name on it.