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Re: Weber MPE-750
Posted: Thu Nov 29, 2012 6:30 pm
by WHY
Matt-----Here is latest files that I have,used A TIMINNG LIGHT and an about 9 to 10 degrees before TDC
Re: Weber MPE-750
Posted: Thu Nov 29, 2012 8:09 pm
by WHY
Matt, having a reall time getting this stuff posted, hope this works
Tony
Re: Weber MPE-750
Posted: Fri Nov 30, 2012 7:24 pm
by WHY
Hi Matt
May need some instructions on loading these files, don'seem to be having any luck with the downloading.
Tony
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Re: Weber MPE-750
Posted: Mon Dec 03, 2012 10:57 pm
by WHY
Am starting to zero in on my ignition problems (with the help that I got from Matt). In the process of "cross breeding" the original schematic wiring diagram of the Weber ECU/EFI system to the Microsquirt system, I have run into the following situation.
The original wiring has the Hall Effect sensor using the 3 wires a little different than the Microsquirt. one wire goes to either a 12 volt source or a 5 volt source (depending on what year model the engine is) then it has one wire going to "engine/chassis ground" and the third is obviously the signal wire. The series of Microsquirt that I have (with the single coax cable used on VR-1) has the cable shield going to pin 32.
Is this a "special ground" because this is where the "ground" from the Hall Effect also connects rather than "engine ground". Also the brown/white wire from the Hall Effect connects to pin 4 on the main connector, is this supply volts or signal ??? And where then does the third wire (not shown) connect to.
At the present I have the Hall Effect wired as per the original engine specs, switched 12 volt supply source, chassis ground and signal to number 4 on the Microsquirt main plug and when set up for crank and cam input does not work. Set up for crank wheel only, fires fine and is somewhat close on timing.
Tony
Re: Weber MPE-750
Posted: Tue Dec 04, 2012 4:08 pm
by WHY
HI Matt
Well today I opened up my wiring harness and "beeped" out all the leads on the cam sensor set up and find one difference than what I posted previously and that is I have the ground from the cam Hall Effect sensor going to "sensor ground" rather than "engine ground" which brings me back to the question "does the cam sensor ground specifically need to go to the same ground pin as the VR coax shield ??????
Tony
Re: Weber MPE-750
Posted: Wed Dec 05, 2012 12:46 pm
by Matt Cramer
I would use the sensor ground wire, not the VR shield, for this.
Re: Weber MPE-750
Posted: Wed Dec 05, 2012 5:02 pm
by WHY
Matt,
Here is latest MSG tune. Some progress, just don't know what direction. This is the current wiring on the cam sensor, supply volts,12--sensor ground-- signal to pin #4 on Microsquirt.
If set to crank wheel sensor only, will get easy spark, RPM on tuner studio of about 300, no spark advance showing on tuner studio but timing light will show about 9 degrees BTDC.
If set to crank wheel sensor AND falling cam sync with inverted spark, may take 4 or 5 starts on the starter to get a spark and then I get RPM,---15.1 degrees advance on tuner studio also cranking indication and timing light fires but no timing marks in sight ????????? Each time I try to crank again it will take 4 or 5 tries to get spark and the other indication also.
Have attached latest MSG (hopefully)
Tony
Re: Weber MPE-750
Posted: Thu Dec 06, 2012 7:10 am
by Matt Cramer
Can you post a screen shot of what you get with the TachRef program, or a composite log from MS2/Extra's composite logger? I'd like a closer look at what the ECU is seeing from the sensors.
It may be better to get it running without the cam sync first.
Re: Weber MPE-750
Posted: Thu Dec 06, 2012 1:21 pm
by WHY
Matt
Thanks for the quick response, but now we are in a total new area of testing and nomenclature. Will try to do as you requested, but first must ask some questions

When you say "take a shot of the screen, do you mean what will be on the laptop screen and then post the picture ? And what is a TachRef program, where do I find it and how do I use it. Same question for the MS2/Extra composite logger
What is frustrating about this is that the 60-2 crank wheel with VR sensor and Hall cam shaft sensor are the stock system for this engine. About the only additional info that I might add would come from a friend of mine who (who recently passed away) was doing the same type of conversion on this engine (experimental aircraft) but using the stock Bosch ECU that came with the engine (a real wiring mess as it was originally for a snowmobile). He told me that when the cylinder is TOP DEAD CENTER the 2 missing teeth are 20 teeth from the VR sensor. I assume he means 20 teeth before the missing teeth and not after, I can physically check this out later if necessary.
Tony
PS. I do not have access at this time to a scope.
Re: Weber MPE-750
Posted: Thu Dec 06, 2012 10:09 pm
by WHY
Matt
Checked the timing wheel this evening using somewhat of a crude arrangement. Used a makeshift feeler guage and inserted it into the opening where the VR sensor goes, then rotated the crankshaft and got a bit of a suprise----Top Dead Center occures 20 or 22 teeth "AFTER" the missing teeth pass the VR sensor ??
Tony