MegaSquirt trigger wheel sensor solution, What's your design?? Options

[draganc]

Hi guys!

I’m planning to upgrade my D-jet system on a 75 2.0 (2056) with a MegaSquirt system.

I’m still debating how to mount the trigger-wheel-sensor and would like to see some of your solutions.

Thank you for your input,
Dragan

[McMark]

My design is available here.

(IMG:http://www.914world.com/bbs2/uploads/post-419-1244942673.jpg)

[hcdmueller]

I bought the McMark trigger wheel. It fits perfectly and the sensor mount is easy to position. I probably could have cobbled something together but it would have cost more and not been nearly as well made.

[SLKWrx]

I've got the same setup and the fit/finish is perfect. Very reasonable as well.

Quick side track, how did you guys plug the distributor hole?

-- Steve

[draganc]

I will go with Van's design (2nd pic from the top) for the plugging the dist. hole:

http://www.ephotomotion.com/914engine/page36.html

BTW, he has done excellent job with this webpage.

Mark, can you pls send me a close-up pic of the final sensor mount? I read you other post and was wondering if the mount shown is/was your final design.

Thanks,
Dragan

[McMark]

The only change in the final sensor mount is that it uses round tube, instead of square tube.

[draganc]

The only change in the final sensor mount is that it uses round tube, instead of square tube.

Thanks Mark! Do you have them in stock?

[McMark]

My newest shipment of wheels is shipping right now. So they are 'backorder' with an expected ship date of next week.

[dr914@autoatlanta.com]

We took a new 009 distributor and designed a pickup for it. Works perfectly but very expensive as we had to machine parts to make this functional and reliable. the best thing though is that it uses the original distributor hole so there is no need to machine anything nor drop the engine
Mcmarks is a very economical solution.

Hi guys!

I’m planning to upgrade my D-jet system on a 75 2.0 (2056) with a MegaSquirt system.

I’m still debating how to mount the trigger-wheel-sensor and would like to see some of your solutions.

Thank you for your input,
Dragan

[draganc]

We took a new 009 distributor and designed a pickup for it. Works perfectly but very expensive as we had to machine parts to make this functional and reliable. the best thing though is that it uses the original distributor hole so there is no need to machine anything nor drop the engine
Mcmarks is a very economical solution.

What is "very expensive"?

[underthetire]

We took a new 009 distributor and designed a pickup for it. Works perfectly but very expensive as we had to machine parts to make this functional and reliable. the best thing though is that it uses the original distributor hole so there is no need to machine anything nor drop the engine
Mcmarks is a very economical solution.

What is "very expensive"?

Ya, inquiring minds want to know. I'd love to put my MS back to fuel and spark. The point pickup (or electronic) sucked for it during start.

[dr914@autoatlanta.com]

here is a picture:

[dr914@autoatlanta.com]

we had all kinds of problems modifying both the flywheel and the fan to install the pickups and NONE were reliable. Plus there was an empty distributor hole AND the fact that to install the megasquirt pickup, the home enthusiast would have to drop the engine, or at least the transmission! What a hassle as compared to just installing a set of carbs. That is why I had my brother in law Galen, an ex GA Tech physics nut case and Porsche perfectionist, design and machine this assembly for us. As you can see by the cover it is very custom and just the one off parts a few at a time take a bunch of precise hours to make.
BUT the result is a direct drop in part that works perfectly and plugs right in, plugging the hole while using it for a modern trigger

[RJMII]

McMark's also turns at the rate of the crank... Does MS adjust for cam input to run both fuel and spark?

I'm running something simliar to what Mark has done, only with the V6.

[Jake Raby]

I am doing some MS test work now.. I ended up using an electromotive 60-2 toothed wheel and electromotive sensor to do the job.

[dr914@autoatlanta.com]

McMark's also turns at the rate of the crank... Does MS adjust for cam input to run both fuel and spark?

I'm running something simliar to what Mark has done, only with the V6.

our system combines sds electronics with cb performance hardware with our distributor

[RJMII]

I am doing some MS test work now.. I ended up using an electromotive 60-2 toothed wheel and electromotive sensor to do the job.

Which MS setup? Did you get your hands on the new MS-III ?

[dr914@autoatlanta.com]

Jake is the man for all of this stuff. I am excited to have him try our distributor and see what he thinks about it. THEN maybe we can have a tete a tete going with two brilliant minds, Jake and Galen!!!!

[JamesM]

Ya, inquiring minds want to know. I'd love to put my MS back to fuel and spark. The point pickup (or electronic) sucked for it during start.

Some advice on using spark control with a distributor pickup…

When using the point pickup for ignition control with Megasquirt it is VERY important that your "cranking speed" variable be set correctly to have decent starts, ie. set to what your engine is actually cranking at. Technically all your variables need to be set correctly but I find this one to be overlooked and it can cause lots of problems.

Just guessing at this or going off specs in a book is not good enough, you need to disconnect the ignition and crank the engine for a bit to see what Megasquirt is reading the exact RPMs at and use that for your cranking speed value. If it bounces around a bit chose a value in the middle or on the lower end of what you are seeing. You may also want to delay ignition events for a cycle or two at start to allow the engine to get up to this speed.

When using the points pickup Megasquirt does a time calculation based on engine speed to decide when to fire the spark. The distributor pickup does not give enough sensor events (or any for that matter) to calculate engine speed for itself by the time the first ignition event occurs so it needs to have a proper cranking speed variable given to it to get the timing right on startup. Getting this wrong, or just leaving set to whatever default value it had, and you wind up with an engine that has a hard time starting, wont start at all, or maybe even give yourself a flywheel with broken teeth from kickback against the starter.

Think about it, if Megasquirt thinks your engine is spinning at 200rpm when cranking and you are actually only getting 150rpm it is thinking your engine is running 25% FASTER THEN IT ACTUALLY IS! Now think about where a 25% discrepancy in your timing would put your spark.

Correctly set cranking speed makes a world of difference when starting!

Of course if you are willing to put in the extra time and money, crank sensors are the way to go.




Another issue you could be having with starting is a weak tach signal due to how the tach input circuit on your MS was set up (usually when people mod them to filter noise), but I won’t get into that here.

[JamesM]

I had an idea for something similar to this but unfortinatly i lack the manufacturing resources at this point in time to accomplish it.

I wanted to put it where the d-jet injector triggers go though in order to pull the tach signal though a stock wiring harness.

I think i have seen an aftermarket wasted spark setup for VW's that uses a similar sensor on top of the distributor setup to the one you have come up with. I will have to see if i can locate it.

We took a new 009 distributor and designed a pickup for it. Works perfectly but very expensive as we had to machine parts to make this functional and reliable. the best thing though is that it uses the original distributor hole so there is no need to machine anything nor drop the engine
Mcmarks is a very economical solution.

Hi guys!

I’m planning to upgrade my D-jet system on a 75 2.0 (2056) with a MegaSquirt system.

I’m still debating how to mount the trigger-wheel-sensor and would like to see some of your solutions.

Thank you for your input,
Dragan