Camshaft sensor for ECU

I'm not sure if a map sensor reacts fast enough. I would have thought a MAP sensor is detecting average vacuum in order to determine air flow (against throttle position, RPM, etc). You want the instantaneous vacuum signal to differentiate between when the intake valve is open verus closed.

At idle, the vacuum differential may be small (between valve open and valve closed), while the average vacuum, overall, is high.
At WOT, at lower RPMs, the differential may be big, while the average is low.

Since the peaks and differentials in one case may get buried by the average in another case, you need a circuit that reacts to and compensates for the average, in order to create a signal based on the valve-opened vs valve-closed differential. A fast microcontroller can probably do the math fast enough, but a good opamp circuit can probably also do it equally well.

Ahh, a turbo adds a new wrinkle. In that case a 15psi sensor will not quite cut it. You'd probably have to step up to something in the 30 psi range.

Is batch-fire just no good?

I have a microsquirt unit sitting here Lou, it's just that i've put so much towards this bike i may as well go with sequential injection & single firing, a big thing is the ECU i have in mind to use also has built in turbo control.

I have GM LS2 coils, 1 per cylinder, GPz 1100 TB's with 350cc (@ 3 bar) injectors & 810cc forged pistons. The engine has also been strengthened to cope with the extra power the Garett T25 turbo will help it with, the turbo will be upgraded after the bike has ran for a while.

Because the coils use so much power i uprated the Z650 battery box to take a GPz turbo battery, then i found a battery the same size that has a higher AH rating. I'm a little concerned that running wasted spark may be too hard on the electrical system, but the ECU turbo control is a big thing!

Here's the bike so far, Z650 (KZ to you guys) with a modified GPz Turbo engine. Since the pic was taken last week all i have done is fitted the cams

Ok, i've just been reading up on OPAmp's, i still don't unserstand them surprisinglly! :blink:

Nor do i know how they turn pressure waves into an electrical signal, i take it they are to be used in conjunction with a pressure sensor of some type?

does this look suitable?
uk.rs-online.com/web/p/product/2355841/?...wiwmaptq&istBid=tzit


& what are the differences between Gauge, Absolute & differential sensors?, i see the same style of sensor with different applications :ohmy:

Sorry Steve, I didn't mean to send you on a search. Op amps are a very handy building block for assembling analog circuits, but they are not the pressure sensor. That Honeywell part number I posted earlier is the sensor. It uses a piezo-electric transducer to convert pressure into a raw, differential signal. The opamps would be used (along with a bunch of other parts) to process the signal and amplify the peak pulses while suppressing the average of signals. But it's not something one would just throw together. It's a lot more complex than hooking up a cam sensor.

LOL, no Lou, its not your fault at all, if someone mentions something i've never heard of or know about a just HAVE to go find out!, that doesn't mean to say i'll understand it though :laugh:

I think i may have edited my last post while you were making yours, is that 30PSI sensor i posted the link of wirth considering?

PS. Is this not a bit early in the day for you guys!?

Using a cam lobe as a sensor does not work very well, it's way to long. I know of two people that tried it, one with a Hayabusa computer and one with a MegaSquirt, neither could make it work. I have a round aluminum ring with a small round steel stud mounted in it that clamps to a camshaft, and the Cam sensor mounted in the valve cover. ZX12 has a teardrop shaped piece of steel held on by a screw at the end of a cam, with sensor in cover.

I know about the pressure wave sensing for TDC off a cylinder, but that's a lot more difficult than a cam sensor (unless you've done a lot).

So, you using the JB Perf board with for injector drivers, and four ignition drivers bolted to the case? I went so friggin crazy on the ZX12 that I had to buy a MS3 to handle it all. Maybe someday I'll get it done :blush:

That man has just landed!! :laugh: A JB what Steve???? :huh:

No, im hoping to use one of THESE ECU's instead now, it has everything i need & more (i think!!), just need to get saving but new babies are expensive!

I'd be hugely interested to see pics of your setup if you have any, is your cam sensor a hall effect one?

750steve wrote: & what are the differences between Gauge, Absolute & differential sensors?, i see the same style of sensor with different applications

There are a few subtle differences in the electronics that may not seem important at first, but for different applications they end up making a difference.

Pressure sensors are just tiny transducers converting force to voltage. That force is the result of different pressures on opposite sides of a sealed piezo element. So really, all of these transducers are a differential pressure transducer.

A gauge-pressure transducer is specialized in that it uses atmoshperic pressure on one side of the element. This is called gauge pressure because that is what typical pressure gauges measure. They are reading pressure above atmoshperic pressure.

An absolute-pressure transducer is specialized in that it uses (ideally) pure vacuum on one side of the element. This reads pressure relative to a vacuum.

A general-purpose, differential-pressure transducer will have two ports in order to compare one port's pressure to another. Connecting one port to a perfect vacuum would make the sensor into an absolute pressure transducer. Similarly, just leaving one port open would make it a gauge-pressure sensor.

On a normally aspirated motor, we generally are concerned with the vacuum relative to atmospheric pressure, so we use a gauge pressure sensor. This lets us know what type of differential there is trying to pull air through the throttle (since it is atmospheric pressure on the outside of the air intake).

I'm not sure how a turbo (or ram-air, etc) effects this strategy. For simply sensing when the cylinder has it's intake valve open, I would think a gauge-pressure or absolute-pressure sensor would work. But if you are trying to measure the pressure differential across the throttle plate, for fuel metering purposes, you would obviously need a differential type sensor.

750steve wrote: ... is that 30PSI sensor i posted the link of wirth considering?

It may be. There are several types in that listing. Does a turbo ever over-pressurize the manifold, even for an instant, before the blow-off valve opens? These sensors are very sensitive and can be damaged by excessive pressures.

The other thing is, it's a raw sensor, the signal will still need to go through amplification, filtering, and processing to compensate for average pressure. All of that needs to happen before it goes to the ECU, preferrably analog so there is no booting time etc. (Opamps were made for this type of task.)

750steve wrote: .
PS. Is this not a bit early in the day for you guys!?

Was at work late banging my head on a project.

steell wrote: Using a cam lobe as a sensor does not work very well, it's way to long. I know of two people that tried it, one with a Hayabusa computer and one with a MegaSquirt, neither could make it work.

If they just hooked it up to the ECU, I wouldn't expect it to work. It needs to go through a threshold-based comparator to really transform the wavy signal into something coherent. Once again, this has to be done to the signal before going to the ECU... another good place to use opamps.

steell wrote: I have a round aluminum ring with a small round steel stud mounted in it that clamps to a camshaft, and the Cam sensor mounted in the valve cover. ZX12 has a teardrop shaped piece of steel held on by a screw at the end of a cam, with sensor in cover.

Both are great way to drive a reluctance pickup, if you have the room and ability to install them under the valve cover.

steell wrote: I know about the pressure wave sensing for TDC off a cylinder, but that's a lot more difficult than a cam sensor (unless you've done a lot).

I agree. If you haven't done a lot of analog signal processing, this would not be the project you would want to learn on. The mechanical problems of fitting a sensor under the cover will be easier to overcome.

Well..as ever, a totally clear cut explaination, thanks Lou

loudhvx wrote: It may be. There are several types in that listing. Does a turbo ever over-pressurize the manifold, even for an instant, before the blow-off valve opens? These sensors are very sensitive and can be damaged by excessive pressures.

I don't know that it does, though i also don't know for certain that it doesn't, even for a nanosecond, as i'll probably only manage 16ish PSI on a good day i was leaving some margin of safety with a 30psi sensor, or so i thought.....the thing is (see below)

loudhvx wrote: I agree. If you haven't done a lot of analog signal processing, this would not be the project you would want to learn on. The mechanical problems of fitting a sensor under the cover will be easier to overcome.

Well in that case thats me right back to a cam sensor! :laugh:


I'll have to talk to this dyno guy tomorrow, as i mentioned in an early post he uses some kind of sensor on no1 TB vacuum to determine when no1 inlet valve is open. The bikes rev to 10000RPM plus (ER6 Supertwin race class) & havent missed a beat yet, i need to find out what that sensor is & when i do i'll post it up to get your opinions

750steve wrote: That man has just landed!! :laugh: A JB what Steve???? :huh:

No, im hoping to use one of THESE ECU's instead now, it has everything i need & more (i think!!), just need to get saving but new babies are expensive!

I'd be hugely interested to see pics of your setup if you have any, is your cam sensor a hall effect one?

JB Performance makes add on boards for MS1 and MS2, including injector driver, ignition driver, and VR conditioner.

MS3 with the real time clock option goes for a little over $700 assembled, and it will do anything the DTA will do plus more, and Tuner Studio tuning software is available for it. Tuner Studio is a heck of a bargain, and makes tuning a lot easier, and it might even work on the DTA (Don't know though).

The ZX12 is just an engine spread out across a workbench with a big pile of boxes containing new engine parts (including MS3). The ZZR1200 engine is sitting in a cradle beside the ZX11 waiting on me to finish the top end and flip it over for a bottom end inspection. It was supposed to be a 5k mile runner when I bought it, but I'm thinking more like 50K at this point. The ZX12 has a 4.6mm stroker crank with a 3mm over bore, for a total of 1394cc and 13.5:1 compression. If that don't get me over 200 mph I'll remove the motor and rebuild it with the turbo kit that's on the shelf. And I also have a turbo header and turbo for the ZZr1200 motor for the ZX11.

Damned medical problems and medication keep me from doing much, it's a real struggle just to get out to the shop, and it's air conditioned!

I'll get there.

Totally agree Stevem the MS3 will do all the DTA does & more, however, if i get stuck the DTA people are a phonecall away, i know im probably over dramatising it but im dipping my toes in unknown waters here (for me). The DTA unit is a bit smaller too which i like.

I think you mentioned our ZX12 project somewhere before, cant wait to see that baby up & howling! If i crack 200 BHP with the '650' i'll be happy, cant see that without upgrading the T25 turbo & headers to custom headers & a GT2052 or something, maybe 1mm bigger exhaust valves too............this build has went OTT already!!

Sorry to hear about your problems again man, i hoped they'd have improved with your treatment by now.