I'm dense. Someone please explain how to calculate triggers

Jon k · Post by **Jon k** » Sun Jun 25, 2006 8:30 pm

Ok I scoured the MegaManual and I am pretty sure its NOT my ignorance, but the only example of wheel trigger calculation is on a 4 cyl with dual sensors and that's so freaking confusing.

I have my GM coil pack in the car now and I want to finally understand what these numbers mean and it just seems that the manual is not very clear on how to go about calculating.

Additionally, "trigger angle", refers to what exactly? I've been told to put in "60" but I have no idea what what 60 degrees is frmo what and I think that may have been why my initial attempt at spark control didn't work.

Someone please, in laymans terms, help a poor guy step for step understand how to calculate wheel settigns on an inline 6 with this wheel? James was kind enough to provide me #'s before, but I don't understand where they came from.

The wheel is 60-2:

Engine rotates clockwise relative to that image. So, I think the sensor is over tooth #55..

Also how do you know what to put for fixed angle and trigger angle?

subie4me · Post by **subie4me** » Sun Jun 25, 2006 10:43 pm

We need to know how your wheel is clocked. What tooth are you on when at tdc?

ptegler · Post by **ptegler** » Mon Jun 26, 2006 3:39 am

Read the EDIS mechanical setup info. It's how you need to setup the wheel.
There is an example of 6 cyl setting on that page. There is also a link to a spreadsheet to dnl that calcs the settings for you on those pages.

Paul Tegler
ptegler@cablespeed.com (ptegler@cablespeed.com)
www.teglerizer.com

----- Original Message -----
From: Jon k (jkensy@comcast.net)
To: megasquirt-mss@msefi.com (megasquirt-mss@msefi.com)
Sent: Sunday, June 25, 2006 11:30 PM
Subject: I'm dense. Someone please explain how to calculate triggers

Ok I scoured the MegaManual and I am pretty sure its NOT my ignorance, but the only example of wheel trigger calculation is on a 4 cyl with dual sensors and that's so freaking confusing.

I have my GM coil pack in the car now and I want to finally understand what these numbers mean and it just seems that the manual is not very clear on how to go about calculating.

Additionally, "trigger angle", refers to what exactly? I've been told to put in "60" but I have no idea what what 60 degrees is frmo what and I think that may have been why my initial attempt at spark control didn't work.

Someone please, in laymans terms, help a poor guy step for step understand how to calculate wheel settigns on an inline 6 with this wheel? James was kind enough to provide me #'s before, but I don't understand where they came from.

The wheel is 60-2:

Engine rotates clockwise relative to that image. So, I think the sensor is over tooth #55..

This post is at: http://www.msefi.com/viewtopic.php?p=127563#127563

Posted by email.

Jon k · Post by **Jon k** » Mon Jun 26, 2006 4:44 am

subie4me wrote:We need to know how your wheel is clocked. What tooth are you on when at tdc?

it goes clock wise, the sensor is over tooth 56 at tdc

Jon k · Post by **Jon k** » Mon Jun 26, 2006 4:49 am

ptegler wrote:Read the EDIS mechanical setup info. It's how you need to setup the wheel.
There is an example of 6 cyl setting on that page. There is also a link to a spreadsheet to dnl that calcs the settings for you on those pages.

Paul Tegler
ptegler@cablespeed.com (ptegler@cablespeed.com)
www.teglerizer.com
----- Original Message -----
From: Jon k (jkensy@comcast.net)
To: megasquirt-mss@msefi.com (megasquirt-mss@msefi.com)
Sent: Sunday, June 25, 2006 11:30 PM
Subject: I'm dense. Someone please explain how to calculate triggers

Ok I scoured the MegaManual and I am pretty sure its NOT my ignorance, but the only example of wheel trigger calculation is on a 4 cyl with dual sensors and that's so freaking confusing.

I have my GM coil pack in the car now and I want to finally understand what these numbers mean and it just seems that the manual is not very clear on how to go about calculating.

Additionally, "trigger angle", refers to what exactly? I've been told to put in "60" but I have no idea what what 60 degrees is frmo what and I think that may have been why my initial attempt at spark control didn't work.

Someone please, in laymans terms, help a poor guy step for step understand how to calculate wheel settigns on an inline 6 with this wheel? James was kind enough to provide me #'s before, but I don't understand where they came from.

The wheel is 60-2:

Engine rotates clockwise relative to that image. So, I think the sensor is over tooth #55..

This post is at: http://www.msefi.com/viewtopic.php?p=127563#127563

Posted by email.

paul can you link to said spreadsheet or explain how the EDIS page is going to help me? My wheel is 60-2 and EDIS is strictly 36-1.

Found the excel spreadsheet but what is meant by "Crank angle when missing tooth aligns with sensor"? Which missing tooth, and my wheel goes clockwise where do I start counting degrees?

subie4me · Post by **subie4me** » Mon Jun 26, 2006 7:41 am

If you were to use 60 degrees as the trigger angle, then find a tooth number that equals 60 degrees before tdc of the first cylinder. Now do the same for the remaining cylinders in the correct firing order. Also , if you want to use trigger return for cranking, then repeat , but locate a tooth that is around 5 to 10 degrees for every cylinder. You could use tooth # 57 for the trigger return for cylinder # 1, and tooth # 6 for the trigger for cylinder # 1 . Just count the same way for the remaining cylinders in the correct firing order.

ptegler · Post by **ptegler** » Mon Jun 26, 2006 8:54 am

After reading your last post.... I see your delima.

You need to set the wheel up so the missing tooth is about
60 degrees BEFORE the sensor when your engine is at TDC.

If you have it at tooth 56...that's only 4 teeth, or 24
degrees. You need to give the ECU time to figure out when
to fire. So by setting it 60 degrees ahead (for a 6 cyl
engine) that gives you lets say... 25rees of crank tining
to have it fire at a max advance of around 35 degrees.
With yours at 24 degrees...you'll never be able to set the
varialbes correctly to get it to fire when needed.
(well you will ...but it'll be a pain in the ass as the
spread is all wrong)

http://megasquirt.sourceforge.net/extra ... wheel.html
3/4 of the way down is a pic of the wheel...the s.s. link
is right there as well.

ptegler

Posted by email.

Jon k · Post by **Jon k** » Mon Jun 26, 2006 9:06 pm

ptegler wrote:After reading your last post.... I see your delima.

You need to set the wheel up so the missing tooth is about
60 degrees BEFORE the sensor when your engine is at TDC.

If you have it at tooth 56...that's only 4 teeth, or 24
degrees. You need to give the ECU time to figure out when
to fire. So by setting it 60 degrees ahead (for a 6 cyl
engine) that gives you lets say... 25rees of crank tining
to have it fire at a max advance of around 35 degrees.
With yours at 24 degrees...you'll never be able to set the
varialbes correctly to get it to fire when needed.
(well you will ...but it'll be a pain in the bum as the
spread is all wrong)

http://megasquirt.sourceforge.net/extra ... wheel.html
3/4 of the way down is a pic of the wheel...the s.s. link
is right there as well.

ptegler

Posted by email.

So you're saying i need to remount my crank wheel? s*** - it's keyed to go on only one way. Is there a way I can make it work without moving it?

Post by **jsmcortina** » Tue Jun 27, 2006 1:53 am

Don't remount your wheel. With most wheels you can allow for any position by tweaking the trigger angle and teeth. (Except low count wheels like for 6-1 or 4-1 where you do need the gap in the right place)

Why do you need new triggers? You've already worked them out once for the wasted COP setup haven't you? Leave them as they are.

"Crank angle when missing tooth aligns with sensor" seemed pretty easy when I wrote it... align your missing tooth with the sensor -> what angle BTDC is your crankshaft at? Stick some timing tape on the damper and read the number.

James

snillet · Post by **snillet** » Tue Jun 27, 2006 2:44 am

I´ve seen a couple of examples where the system doesnt´recount for cylinder 1...... so the ignition cycle runs from cylinder 2 or 3 on a 4 cylinder engine.

Weird but excisting.

Post by **jsmcortina** » Tue Jun 27, 2006 2:49 am

snillet wrote:I´ve seen a couple of examples where the system doesnt´recount for cylinder 1...... so the ignition cycle runs from cylinder 2 or 3 on a 4 cylinder engine.

Could you provide some more details?
The only time this is likely to occur is if one of the trigger teeth specified doesn't exist. i.e. on a 60-2 the count goes from 2 to 59.
On a 36-1 the count is from 1 to 35.

James

Jon k · Post by **Jon k** » Tue Jun 27, 2006 3:24 am

jsmcortina wrote:Don't remount your wheel. With most wheels you can allow for any position by tweaking the trigger angle and teeth. (Except low count wheels like for 6-1 or 4-1 where you do need the gap in the right place)

Why do you need new triggers? You've already worked them out once for the wasted COP setup haven't you? Leave them as they are.

"Crank angle when missing tooth aligns with sensor" seemed pretty easy when I wrote it... align your missing tooth with the sensor -> what angle BTDC is your crankshaft at? Stick some timing tape on the damper and read the number.

James

James the numbers I have from before are the ones generated by the spreadsheet with a 60 trigger angle but im not sure where 60 degrees comes into play on my setup. The angle from 1st tooth to sensor is less than 60 if you count that way or more than if you go the otherway.... I wish I understood this.

Peter Florance · Post by **Peter Florance** » Tue Jun 27, 2006 5:12 am

Jon k wrote:
jsmcortina wrote:Don't remount your wheel. With most wheels you can allow for any position by tweaking the trigger angle and teeth. (Except low count wheels like for 6-1 or 4-1 where you do need the gap in the right place)

Why do you need new triggers? You've already worked them out once for the wasted COP setup haven't you? Leave them as they are.

"Crank angle when missing tooth aligns with sensor" seemed pretty easy when I wrote it... align your missing tooth with the sensor -> what angle BTDC is your crankshaft at? Stick some timing tape on the damper and read the number.

James

James the numbers I have from before are the ones generated by the spreadsheet with a 60 trigger angle but im not sure where 60 degrees comes into play on my setup. The angle from 1st tooth to sensor is less than 60 if you count that way or more than if you go the otherway.... I wish I understood this.

Will this work:

If TDC is tooth 56, then TDC-60 degrees is tooth 46 (10 degrees per tooth)? So would he use 46 as trigger A? And 54 for return A?

I worked this out for M30 and was only 2 degrees off. I used my timing light to set it; to borrow a term from the Aussies, I'd be 'stuffed' without my timing light.

I hope I haven't screwed this up..

Post by **jsmcortina** » Tue Jun 27, 2006 5:18 am

Jon k wrote:im not sure where 60 degrees comes into play on my setup

The way the code is written we want a "trigger" at around 60BTDC. It is unrelated to the position of the missing tooth.

James

Jon k · Post by **Jon k** » Tue Jun 27, 2006 11:12 am

jsmcortina wrote:
Jon k wrote:im not sure where 60 degrees comes into play on my setup
The way the code is written we want a "trigger" at around 60BTDC. It is unrelated to the position of the missing tooth.

James

James - would what Peter florance suggested work then?

Jon k · Post by **Jon k** » Wed Jun 28, 2006 5:10 am

Guys - what should I do here?

The thing that troubles me is that AEM EMS, Tec3-R, etc., all are able to run on the stock crank wheel and stock CPS position - am I not going to be able to do this with MS? Please help I really want to get this car finished... here is why:

Post by **jsmcortina** » Wed Jun 28, 2006 5:32 am

Could you explain why the wasted COP didn't work (in detail) and why you think you need different trigger settings for wasted COP compared to wasted spark.

You had working trigger settings didn't you ? so just use them - the SAME ones because you are still running wasted spark.

The wheel and sensor do NOT need moving. Plenty of people have got oem 60-2 working just fine and nobody has moved their wheel.

James

Jon k · Post by **Jon k** » Wed Jun 28, 2006 5:36 am

jsmcortina wrote:Could you explain why the wasted COP didn't work (in detail) and why you think you need different trigger settings for wasted COP compared to wasted spark.

You had working trigger settings didn't you ? so just use them - the SAME ones because you are still running wasted spark.

The wheel and sensor do NOT need moving. Plenty of people have got oem 60-2 working just fine and nobody has moved their wheel.

James

The coil on plug didn't work, I believe because not only was the dwell probably not right (i changed it around a lot!) but it seems like I was getting bad starter kickback. I want to run the GM coil pack for now so I can at least eliminate variables caused by the COPs. I guess I will just try those numbers again, but it made for some nasty noises when I cranked the car last time. I am not sure those #s were working numbers because I don't fully understand how they come about - I know they came from the excel spreadsheet but it seems like my instance should be different since the missing teeth are to the left of the CPS when at TDC.

Peter Florance · Post by **Peter Florance** » Wed Jun 28, 2006 5:37 am

Jon
Not sure what to tell you. If you've got an adjustable timing light, you ought to be able to determine whether my suggestion is the correct trigger or not.
That's what I had to do when I first fired up M30 motor.

4 cylinder triggers should be 30 teeth apart; 6 cyl should be 20 teeth apart.

If you don't have a timing light, I strongly suggest you buy or borrow adjustable timing light if you're going to be breaking ground in EFI applications.

Note this trigger wheel stuff is brain straining at first. It will get easier if you work it out yourself, so you understand the relationship. I always draw a picture to help me understand the #'s on the wheel

I'm running fine on 60-2; the system can do it, but the application is up to you.

You can do this.

Peter Florance
First Fives.Org - The E12 Registry
1981 Euro BMW 528i w/3.5L & Megasquirt Fuel Injection
1981 US BMW 528i "Repo Car"
http://www.firstfives.org
mailto:peter@firstfives.org (peter@firstfives.org)
ssr# 284

From: Jon k [mailto:jkensy@comcast.net]
Sent: Wednesday, June 28, 2006 8:11 AM
To: megasquirt-mss@msefi.com
Subject: I'm dense. Someone please explain how to calculate triggers

Guys - what should I do here?

The thing that troubles me is that AEM EMS, Tec3-R, etc., all are able to run on the stock crank wheel and stock CPS position - am I not going to be able to do this with MS? Please help I really want to get this car finished... here is why:

This post is at: http://www.msefi.com/viewtopic.php?p=128009#128009

Posted by email.

Jon k · Post by **Jon k** » Wed Jun 28, 2006 5:43 am

Thanks Peter - I know its GOT to be possible its just frustrating! I am ordering MSD spark plug wires, then i will be buying a timing light with advance. At the very least, I can hook up the GM coil and leave the stock coils in and see that its sparking correctly @ the GM coil.

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