Cam positions sensors for sequential Megasquirt...

Been thinking about sequential injection. Megasquirt can support it (with some mods) and I was wondering what could be used as a cam position sensor. Could a dizzy be used as it has a hall sensor in it? The only thing I can see as a problem is of course you can adjust a dizzy for timing, so thus you could do the same fro the cam position sensor. This of course isn't really desirable, so has anyone got any suggestions on how else to implement a cam position sensor on a 16v head? Also is a normal cam position sensor, say from a VR, operate with a toothed wheel, or is it a single position used in conjection with the crank trigger?

VR cam position sensors run on a trigger bolted onto the end of the camshaft which is keyed into the cam sprocket. Guess you could make something similar in the 16v dizzy hole?

Hmm, I wonder if you could actually use a VR cam sensor then? Is it a variable reluctor type sensor or a hall effect?

why not use the 60-2 polo wheel?

dirtytorque wrote:why not use the 60-2 polo wheel?

For the cam position?

i rekon..

there in phase.
surely there is a way?!??

Hmmm, well, I'm going to be using a 32-1 toothed wheel welded onto the end of the auxiliary pulley for crank signal, and then run direct coil drive for the four COPs, would I be able to use that signal fro both that and cam position?

mrbeige wrote:Hmmm, well, I'm going to be using a 32-1 toothed wheel welded onto the end of the auxiliary pulley for crank signal, and then run direct coil drive for the four COPs, would I be able to use that signal fro both that and cam position?

On a golf VW refer to the hall sensor has a cam position sensor in the OBD2 software.
These things just tell the computer where the engine is in their cycles.
Using either the crank or the cam as the point of reference.

What are your code plans MrBrown?
I guess you will have to get said pulley balanced etc..
What do you thing will be the advantages of using this system over just using the hall sensor from the dizzy?

mrbeige wrote:Hmm, I wonder if you could actually use a VR cam sensor then? Is it a variable reluctor type sensor or a hall effect?

Cam - Hall effect
Crank - VR

kevhaywire wrote:

mrbeige wrote:Hmm, I wonder if you could actually use a VR cam sensor then? Is it a variable reluctor type sensor or a hall effect?

Cam - Hall effect
Crank - VR

Cheers Mr Wire

dirtytorque wrote:What are your code plans MrBrown?
I guess you will have to get said pulley balanced etc..
What do you thing will be the advantages of using this system over just using the hall sensor from the dizzy?

Going MS1 Extra. Decided to use the dizzy as trigger and use the standard coil for now, but directly from MS (VB921?), then rather than have to get pulley and trigger-wheel balanced, just wait and fit a Lupo trigger-wheel.

The reason I was asking was to have two separate signals for cam and crank so I could go sequential injection, but is it possible to use the same trigger for both? I would think that the crank would do two revolutions to the cam's one. Mind you I suppose that doesn't really matter as you just tell MS what to expect?

tbh I never looked into sequential injection.
Digifant uses a batched configuration on the g60 and so I thought it would simplify the install if I went the same way.
I didn't want to make it unnecessarily complicated,expesially as it was my first venture into MS.
I wanted to follow a well trod path.
Boring I know.

Nothing wrong with that. I'm only thinking ahead really. Going to start simple anyway, but I like the idea of sequential. That I suppose is the advantage of MS, you can keep adding features.

Thread resurrection time....

So, I'm sure I've seen a cam position sensor mounted where the standard 16v dizzy goes, has anyone seen this, and if so, where??

You should be able to use the dizzy's hall sender as a cam position signal.

You would have to work out the position of the sensor in relation to crank angle and also the optimum injection timing. Most tuners fire the injectors onto a closed intake valve (helps with atomisation as the droplets break up and disperse around the valve and stem) just as the induction stroke starts, and that being the 'End' of the injection time. Very few people use "Start" of injection, but that's not to say you can't, or it's wrong to use it.

If you have extremely good injectors, you can fire them into an open cylinder (intake valve open) but some folk find this trickier to get right.

If I'm talking nonsense, look it up on the old netaroo..... it's quite important stuff I might not have explained it very well.

P.S. Sequential won't give you anything worthwhile unless it's tuned to perfection. It'll run and work fine if it isn't, but you won't get the main benefits if it's not optimised.

You can run the COPs as wasted spark btw, so you don't need a cam signal for that. If you want sequential spark firing, then you would need one.

Hmmmm, ok. I'll be running wasted spark, so no need for the cam position for that, just have strategies that expect a cam position for sequential.

I did wonder if an older Audi V8 would have cam pos sensors as, the heads are almost identical to the 16v.

Here is what I'm thinking about...

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as the wired one said the the dizzy on a 16v is a cam position sensor.
VW are just doing the maths to convert to crank position.

Yeah, but doesn't the dizzy have four slots in it for each trigger of the spark? How are you supposed to know where the cam is? You need one slot and then the software can sync between the crank and cam, as the cam sensor will see on trigger per engine cycle (rather than engine revolution) due to the cam running at half the speed of the crank.

Yeah that's a good point. Dizzys give 4 sparks per revolution of it's shaft, but for wasted spark you only want 1.

There must be something on the Megasquirt sites about using Dizzy's for cam sensors as the yanks use squirt on valvers all the time?

They don't use the dizzy as cam, but rather as crank position.

surely as the two(crank/cam) are in phase if you know where one is then you can calculate where the other is..

they are in phase, but the crank turns twice when the cam turns once. You may know where top dead centre is from the crank, but the cam could be in one of two places.

Oh and depending on the cam sensor, they either have; 1 tooth/gap, 4 but not equally spaced for simple two stage VVT, or lots with a missing tooth if the engine has fully variable VVT

mrbeige wrote:they are in phase, but the crank turns twice when the cam turns once. You may know where top dead centre is from the crank, but the cam could be in one of two places.

Yes I know,I was thinking you could use alternate signals but thinking about it you'd need to know where true tdc was first and I guess with a hallsender you just can't know that.



Toothed wheel mate.

you think a full toothed wheel? I reckon a single slot would suffice

Think I've found a solution....

16v Dizzy with a 20v cam position assembly windowed wheel

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