MPi cam sensor trigger point
Turbo Mini Forums

Does anyone know what is the angle at which the cam sensor gets triggered by the cam lobe? I know the crank missing teeth are at 30, 60, 210 and 250 degrees but I need to know where the cam signal comes in (even if approximate). I searched the forum but I haven't found anything.

I want the siamese code to be able to use the standard MPi setup in addition to the common 36-1 setup. In the case of the 36-1 wheel, the cam signal can be pretty much anywhere (except at the missing tooth) and just resets the engine cycle so the following missing tooth is tooth 0 of the 720 degree cycle.

Jean

http://www.jbperf.com/

I dont know what the angle is but I believe turbodave had one for a while and was sending it to Marcel for maping.

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=7312

"sorry, Jedi mind tricks don't work on retards" Mediocre Films 2008

Yes, and I did send it to marcel, and he plotted it out - so I assume he must still have it somewhere...

I assume this was for the cam timing and not for the cam trigger. But it shouldn't be a problem to plot the cam trigger also.

http://www.jbperf.com/

I meant to do this but i have now machined all the lobes off of it, except the cam sync

Why does it matter what the value is as all it does is ensure the start of the sequence takes place on number one cylinder on the exhaust stroke, the injection timing is done from the crank trigger? I will hazard a guess at 70 degrees BTDC (thats 140 cam degrees)

This is how VEMS gets round sequential injection without a cam sync. it either injects on the exhaust stroke or the compression stroke, either way it injects on a closed valve. That wont work on the Mini, obviously

Edited by Sprocket on 12th Dec, 2008.

Yes - it was just to plot the timing. I am guessing you're just looking for something approximate, rather than exact aren't you?

It matters because the decoder doesn't exactly work like that for patterns other than a simple missing tooth wheel. For the 36-1 it just does that but for the MPi pattern there is also a pattern validation done to make sure the sync is correct.

And 70 crank degrees is 35 cam degrees not 140. If you're able to check the actual value, it would be great.

Jean

http://www.jbperf.com/

Bad day at work

I think I may be able to use the cam trigger just to sync the first missing tooth so I won't need precise timing information.

I have emailed Marcel to see if he has the information but if I can get a confirmation on the information above that might be enough. So the cam signal come in before TDC of cylinder 1 at about 70 deg BTDC so it means it is located somewhere between the 4th missing tooth (250 deg or more precisely, the 8th missing tooth at 610 deg) and the first missing tooth (30 deg).

Jean

http://www.jbperf.com/

Colin,

I would appreciate if you could confirm the information above. I basically just need to know in which quadrant it happens (as long as it's not on a missing tooth).

Thanks,
Jean

http://www.jbperf.com/

Thanks, that should give an idea as long as I also have an idea of where the sensor is. I've never even seen an MPi engine so I'm pretty much flying blind here.

http://www.jbperf.com/

Jean,

I too have never seen an MPi engine but I do have a copy of Rover's technical manual (RAVE) on disc so have searched that. It doesn't have the actual information you want but it does say something I wasn't expecting...

It's a protected pdf so I can only copy the text, not the pictures....

"ENGINE MANAGEMENT SYSTEM - MEMS
DESCRIPTION AND OPERATION 3 REVISED: 12/96
BASIC IGNITION TIMING
Crankshaft position sensor
The speed and position of the engine is detected by
the crankshaft position (CKP) sensor which is bolted
to, and projects through, the engine adaptor plate
adjacent to the flywheel.
The CKP sensor is an inductive sensor consisting of
a bracket mounted body containing a coil and a
permanent magnet which provides a magnetic field.
The CKP sensor is situated so that an air gap exists
between it and the flywheel. Air gap distance is
critical for correct operation.
The flywheel incorporates a reluctor ring which
consists of 32 poles spaced at 10° intervals, with 4
missing poles at 30°,60°, 210° and 250°. The
missing poles inform the ECM when to operate the
groups of injectors. When the flywheel rotates, as a
pole passes the CKP sensor it disturbs the magnetic
field inducing a voltage pulse in the coil. This pulse
is transmitted to the ECM.
By calculating the number of pulses that occur within
a given time, the ECM can determine the engine
speed. This is a primary input necessary to make
the engine run.
Camshaft position sensor
The camshaft position sensor has two functions. The
first is to enable the ECM to run a sequential fuelling
mode. The second is to measure the actual cam
period, this measurement is achieved using teeth on
the camshaft to indicate when the valve opens and
closes.
If the camshaft position sensor fails when the engine
is running, the engine will continue to run normally in
sequential fuelling mode. If the sensor fails before
the engine is started, the engine will start but run at
a reduced rev limit in comparison to the normal rev
limit of 6500 rpm. Camshaft position sensor failure
can be identified using TestBook."

The bit that surprised me is it says "teeth" (plural) for the cam sensor and that it has a second function to measure the cam period....

All other phase sensors I've seen just measure one point ???

Unless of course the technical manual is wrong....

Rod.

Schrödinger's cat - so which one am I ???

Rod I think Rover just copied that extract over from the Rover KV6 strategy, where I can only assume, by the nature of the ECU, that there are two pairs cams and two sensors it is a V6

I wouldn't be surprised.......

They rarely did anything properly, yet the version I've got is supposed to be an updated one :$:$

I found a photo of the cam here (EDIT-link didn't work, I'll copy the pic...) so if yours has the lobes machined off, it might help interpolate which quadrant at least

EDIT - piccy

From AC Dodd's ML Motorsports site

Edited by Rod S on 17th Dec, 2008.

Schrödinger's cat - so which one am I ???

From the picture, it doesn't seem to have teeth but just a lobe (but why is it split in 2?).

And can I assume that the sensor is 90 degrees from the top so the lobe will have the same shift with respect to TDC?

http://www.jbperf.com/

Schrödinger's cat - so which one am I ???

Good point about the cam vs crank degrees. I forgot about that...

http://www.jbperf.com/

The lobe is split because rover use what is a crank sensor. The sensor has a pin protruding, the pin passes between the narrow two lobes



The sensor is mounted in the 'back' of the block at what could be considered 90 degrees ( its mounted horizontal)

I'll sort this out tomorrow chaps

One more thing to confirm: this is a VR sensor, right? I just want to be sure there's a need for the VR conditioner on the cam signal.

http://www.jbperf.com/

yes it is VR

Did we get a definitive answer ???

I'm just building my phase sensor now and there is some kind of logic that says replicate the MPI phase position/angle, ie, try and keep some similarity across what we are all doing.

Schrödinger's cat - so which one am I ???

Nothing since the last post...

With the 36-1 wheel, the cam sensor position is less critical. As long as the trigger is somewhere before the missing tooth and before TDC of cylinder 1 it will be fine. Actually, it can be anywhere other than at the missing tooth and it will be fine but other positions might require switching injector channels and/or spark channels around.

Jean

http://www.jbperf.com/

Jean.

Understood ...

It would still be nice if we could agree on a single point for all of us following this route - it would remove at least one variable when testing if we all did the same !!!

Rod.

Schrödinger's cat - so which one am I ???

I had the flu over the period I said i would get this done, Since then I have been trying to finish a few things for the wirral llandudno, and its been too bloody cold to do anything in the garage

I will get to this, I am still tripping over the 'shaft' in the garage. I left it out on purpose to remind me to do this