MS3X ignition timing setup question

[billjam]

Check post #18 ... someone has had a senior moment.

The instructions in the MS manual don't seem to relate to the configuration of a 3.6 flywheel and timing sensor. Can someone who has done this step confirm my understanding of it?

I am trying to define the value for Tooth#1 Angle (deg BTDC) for the TunerStudio Ignition Options setup screen.

With engine at TDC, I should count the number of gaps to tooth#1 in the direction of rotation and multiply by the angular size of the teeth (6 degrees for 60-2 flywheel).

This result gives me 54 gaps, which equals 324 degrees. Correct?
It's just that all examples in the MS manuals have a much smaller angle, usually 80 degrees

[DUK]

Megasquirt MSEXTRA / MS3EFI • Tri-tach install on a Porsche 911 3.2L with 129+1 tooth help (View topic)

This thread may help.

[TimT]

The system does not start counting teeth until the sensor has passed the two missing teeth... I does not count the missing teeth because it can't see them...

Based on the picture you provided and where you think the ignition/injection events start is wrong..

Depending on where you mount the sensor, you should be somewhere between 70-80 deg crank offset.

[TimT]

I should have written the system does not start counting teeth until after edge of the last tooth before the missing teeth passes the sensor

[TimT]

Sorry for the three replies in a row....

Just remembered helped another guy out configuring a missing tooth ignition set up with an aftermarket ECU....I think I explained what you need to do on this

Thread

Hope it helps

[roblav]

I'm still struggling with this too - not running yet... but I believe the crank angle for 6 cylinder engine should be about 60 degrees. Apparently they recommend it going there because of variation in the crank signal - 60 degrees minimizes it when the critical firing steps occur.

I'm about ready to throw in the towel and go with PMO46's and crankfire... but I may try Clewitt's pulley tooth crank sensor mount system first.

[rsscotty]

If one is using the stock 60-2 teeth on the flywheel, and the stock ref. sensor mount, the CRIP or crank reference index position is 86. That is the number I use with Motec. Of course when it is running you verify with a timing light that this is correct.

[billjam]

Originally Posted by rsscotty

If one is using the stock 60-2 teeth on the flywheel, and the stock ref. sensor mount, the CRIP or crank reference index position is 86. That is the number I use with Motec. Of course when it is running you verify with a timing light that this is correct.

Scott,
The terminology and requirements might be different with Motec.
MegaSquirt manuals clearly define the setup procedure for determining the position of Tooth#1 BTDC as ...
With engine at TDC, count the number of gaps to tooth#1 in the direction of rotation and multiply by the angular size of the teeth (6 degrees for 60-2 flywheel).
I was also expecting something like 80 degrees, but when I follow these steps on a 3.6 flywheel with 60-2 teeth clearly gives a much different result.

[billjam]

Originally Posted by TimT

The system does not start counting teeth until the sensor has passed the two missing teeth... I does not count the missing teeth because it can't see them...

Based on the picture you provided and where you think the ignition/injection events start is wrong..

Depending on where you mount the sensor, you should be somewhere between 70-80 deg crank offset.

Thanks Tim.
Not sure what you mean there about where the ignition/injection events start. I don't know where that should be at present - that's what I am working towards figuring out.
The picture is what it is. It is a standard flywheel and sensor arrangement (that I don't want to change) and I am sure many others have used without problems.

Originally Posted by TimT

Sorry for the three replies in a row....

Just remembered helped another guy out configuring a missing tooth ignition set up with an aftermarket ECU....I think I explained what you need to do on this

Thread

Hope it helps

Don't apologise to me for hogging Wayne's server space! Your input is appreciated.
I looked through your linked thread but it relates more to setting up a conventional trigger wheel rather than configuring an ECU to an existing trigger wheel and sensor location.

[sjf911]

Your calculations look correct to me as long as that is really TDC #1.
Here is my 60-2 wheel for reference. Tooth #1 is just above Z1 mark and the missing teeth are immediately to the right but difficult to see. My sensor is over the 11th tooth after the missing teeth so my tooth angle #1 is 66 degrees.

[Pazuzu]

Maybe I'm completely missing the problem here, but isn't it a case of the crank pulley rotating opposite the flywheel ring? The sensor needs to trail the missing teeth on the flywheel, not lead them. It would be clockwise of the missing teeth. When you're looking at the crank pulley, it's counterclockwise of the missing teeth.

[billjam]

All I really need is for someone with MS3X on a 3.6 engine with standard 60-2 flywheel and sensor to chime in with their version of events!

[sjf911]

Originally Posted by Pazuzu

Maybe I'm completely missing the problem here, but isn't it a case of the crank pulley rotating opposite the flywheel ring? The sensor needs to trail the missing teeth on the flywheel, not lead them. It would be clockwise of the missing teeth. When you're looking at the crank pulley, it's counterclockwise of the missing teeth.

The MS unit starts counting teeth after the missing teeth pass. The number of teeth that pass the sensor after the missing teeth and before the engine reaches TDC is your offset. For me it is 11 teeth, for the OP it is 54. To reduce that offset you have to relocate the sensor or reindex the missing tooth wheel, not a simple process in this case. Is there a problem in MS with this large of an offset?

[Pazuzu]

Originally Posted by sjf911

The MS unit starts counting teeth after the missing teeth pass. The number of teeth that pass the sensor after the missing teeth and before the engine reaches TDC is your offset. For me it is 11 teeth, for the OP it is 54. To reduce that offset you have to relocate the sensor or reindex the missing tooth wheel, not a simple process in this case. Is there a problem in MS with this large of an offset?

I didn't realize that MS can deal with an error like that, I thought you had to make sure that your offset was 60-65 degrees plus or minus a small error (few degrees). Maybe that MS3 vs MS2.

[sjf911]

It looks like they suggest 60 degrees as optimal but not required:

"While the code can cope with any sensor/tooth phasing, during cranking the rpms vary up and down greatly as the engine rotates. It is desireable to place the missing tooth such that it passes the sensor when the engine is somewhat stable. The OEMs have found that certain tooth#1 angles work well and it is worth following their lead."

Megasquirt-3 MS3 Trigger Wheel

That would suggest that if that is an OEM flywheel then it may well be fine since Porsche/Motronic use it.

[billjam]

Originally Posted by sjf911

The MS unit starts counting teeth after the missing teeth pass. The number of teeth that pass the sensor after the missing teeth and before the engine reaches TDC is your offset. For me it is 11 teeth, for the OP it is 54. To reduce that offset you have to relocate the sensor or reindex the missing tooth wheel, not a simple process in this case. Is there a problem in MS with this large of an offset?

All correct.
Your question is basically what I was asking - is 324 degrees OK? It just seems a long way off the norm and not what I expected, but I guess it has to be what it is!
I will setup with 324* and see what happens. It will either run or it won't, so then I'll revisit the subject if I need to.
I am a few weeks off actually running the engine, so I'll try and remember to post the result.

[rsscotty]

Bill,

Shown below is where all of our motors are in relation to engine being at TDC #1 and where the missing teeth are. We are running falling edge on the reference sensor. Our CRIP number is 86 degrees. I am counting right at 15 teeth between the ref sensor and the missing teeth.

[billjam]

Originally Posted by rsscotty

Bill,

Shown below is where all of our motors are in relation to engine being at TDC #1 and where the missing teeth are. We are running falling edge on the reference sensor. Our CRIP number is 86 degrees. I am counting right at 15 teeth between the ref sensor and the missing teeth.

Great Scott!
I can see that you have a 3.6 so I went back and double-checked everything. Right from the outset, I knew something wasn't right, which is why I posted.
Would you believe that I had TDC, but wrong cylinder!
Some time ago (this engine has been two years in the making), I marked what I thought was #1 TDC on one of the pulley timing marks with white paint and I was using that as my TDC reference rather than actually checking the position of #1 piston. It turns out that I painted the wrong notch in the pulley.

My apologies to everyone who chimed in trying to help.
My flywheel and timing setup now looks very much like Scott's - surprise, surprise.

[Jaskas]

Do you need a basic tune for your 3.6 ? I can send you mine if you need one to start with.

[billjam]

Originally Posted by Jaskas

Do you need a basic tune for your 3.6 ? I can send you mine if you need one to start with.

Absolutely! That would be great.
I have done the basic setup in TunerStudio, but still learning how it works so it would be good to have some real maps to play with.

You can email the files to me at
bill . james at clough . com . au

This is where I finished yesterday. Engine in today