crank sensor wheels

[fiero]

hi i am in the process of changing my 85 fiero from distributor to coil pac and began thinking about whether i should be using a magnetic wheel or hall effect.i would think hall effect would be easier to identify #1 position or am i overthinking this?

[fiero]

no i am upgrading to 1227730 ecu

[1project2many]

Sensor choice will depend on the ignition type. The GM DIS uses a magnetic sensor with a six plus one notch configuration to determine start of ignition sequence.

[fiero]

thats what i thought. i will have to locate one that will fit my 2.8 block. i have a 3.1 crank in it but the block will not accept the factory magnetic pick up.

[dave w]

I have CAD drawings for a 2.8 V6 externally mounted / harmonic balancer mounted trigger wheel. Additional fabrication required for mounting the crank sensor.

For prototyping purposes, I suggest having a trigger wheel water-jet cut using ABS plastic.

dave w

14914

[fiero]

thanks for that. i also found a set of drawings to cut the wheel directly into the balancer itself. i've got some time so theres no rush.i will try to pick the one that works for the skills i have.

[1project2many]

If you are building your own sensor bracket be sure to work out the correct wheel alignment angles. I usually choose to match a factory application with DIS in case I need to make a diagnosis later.

[fiero]

thanks for the info

[Six_Shooter]

This is what I did on my 1985 Jimmy originally, then the wheel was transferred to my Nissan L28 (I used GM EMS and DIS on it) and then onto my LX9, where it is currently.

I did modify the sensor mount between when I used it on the Jimmy and using it on the LX9, basically I moved the main support farther away from the block and shortened the sensor bracket. I also shortened the main support as I didn't need as much adjustment as I thought I did.

[fiero]

nice job on that setup.my only question what are the dimentions of the slots in the wheel?i have no problem machining my own parts.it was suggested that i use a crank trigger from a mid 90's escort.thanks for your help . fiero bill

[1project2many]

The mid '90s Escort wheel works with Ford distributorless ignition. The Ford system may not work with a GM computer.

Here is the GM timing diagram for a 60 deg V6 wheel and an image of the wheel with the sensor location and notch locations for reference.


IIRC the notches are about 2 degrees wide. The actual width will depend on the circumference of the trigger wheel.

[fiero]

sorry the picture you posted is a big blurry blob on my pc.

[fiero]

according to my calculations 2 degrees would only be .122 of an inch on a 7 " wheel or are my calculations incorrect ?

[1project2many]

That seems about right. I have a crankshaft with those notches present. I'll try to rremember to get some measurements over the next couple of days.

[fiero]

cool thanks for that.hope you have a good holiday. fiero bill

[Eds]

sorry the picture you posted is a big blurry blob on my pc.

As you, on my PC I have the same issue however if you have an Android based phone using Chrome, I believe you can open and see the picture. At least, I can.

[NomakeWan]

sorry the picture you posted is a big blurry blob on my pc.
It’s because Photobucket is useless. There are free extensions available for Firefox and Chrome that can fix it; look for “Photobucket Embed Fix” or heck just “Photobucket” in your browser’s extension store.

[Six_Shooter]

The picture looks fine on my PC. *shrug*

I don't recall the exact dimensions of the notches, but it was basically made to be very close in size to the original crank wheel, to avoid any errors in resizing at the time. Because when I first did this, I was the first to do this AFAIK, meaning modeling an OEM trigger wheel to use as an external on a different engine, aftermarket crank triggers had been around for a long time when I did this, just never came across any OEM type wheels for this type of use up to that point. Another idea I had at the time was to modify a distributor to hold a custom wheel with the pattern doubled up, but I felt due to the reduction in overall wheel diameter the need to double up the pattern (a total of 14 notches), that it may not work as well and be very hard to make. Knowing what I know now, I'm sure it would have been fine.

Anyway, I think the GM wheel might be closer to 20 degrees or so. The actual width doesn't seem to be the issue, just as long as there is a solid change from high to low state in the signal, since the ICM triggers off only one of the edges, not both and I want to say that it's the falling edge. If you look at my pictures you'll see the... lets call it a tooth... between the home notch and one of the TDC notches is very, very small, and I was worried about this at the time, because it did end up being smaller than the OEM tooth, but has worked perfectly. This tooth would only be 1 to 2 degrees wide, and is always picked up. I'm now running Megasquirt with the crank trigger directly to the ECU and the tooth log has never missed the small tooth, other than when I've adjusted things way out of where they need to be, but that's a different thing all together.

Also, as 1project2many has said the Ford trigger wheel is for the Ford EDIS system and this will not interface with the GM ECM, at least not directly. The signals are similar, but not the same between the Ford EDIS and the GMDIS. I'm sure the EDIS would trigger the ECM for the RPM input fine, but timing control will likely not be reliable, and would likely take some sort of interface between to make it work properly. Easier just to use the proper trigger wheel for the GMDIS and use it.

[fiero]

thanks for the input.I have got all my ducks in a row now and will tackle the upgrades over the next few weeks and will post the outcome soon.

[1project2many]

sorry the picture you posted is a big blurry blob on my pc.

I apologize. Somehow I lost track of this.

I've uploaded new images and edited the previous post so they should be clear. The problem was photobucket and since they're hosted on my account I was able to see them. Here is a drawing for a DIS wheel with dimensions originally borrowed from delcohacking.org:
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?1997-Ideas-for-4-cylinder-MPFI-Toyota-22RE-with-GM-ECM&p=24827&viewfull=1#post24827

Also, there is excellent reference material to be found here: GM Ignition Systems. (http://faculty.ccbcmd.edu/~smacadof/Books/A8StudentWorkBooks161/SWB_a8_m09_Final.pdf)

Be sure to update us on your progress.

[NomakeWan]

Looks like you accidentally uploaded the blurred version of one of the images to your earlier post. ;)

[fiero]

thanks 1project2many. that should be easy to adapt to my project.i will use tha as a basis for a wheel to mount on my balancer

[1project2many]

Looks like you accidentally uploaded the blurred version of one of the images to your earlier post. ;)

Yes it does. I have no idea how I did that. I swear it looked fine this morning.

How about now?

[NomakeWan]

Yes it does. I have no idea how I did that. I swear it looked fine this morning.

How about now?
All good! Thank you for your hard work.

[1project2many]

I appreciate everyone's help. This place wouldn't be half of what it is without so many good people.

[fiero]

sorry I did not reply sooner but I got behind with the virus around.I built a tone wheel and because I am deleting my AC i trimmed my AC pulley off and welded the wheel in its place. this leaves the engine belt aliened. i built an adjustable crank trigger bracket and wired everything in.I turned the key and it fired up instantly. wow.right now at idle it is showing 8 degrees of advance with a 1990 chev cavilier chip in it.I anm having problems down loading the 88 adx file from tuner pro so i have not been able to look at it with my laptop.any tips on downloading tuner files ?