Twins with Twins, Anyone?

kidturbo

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Tonight I wired up the DD GPS pulse generator that controls shifting lockout to the TCM output shaft speed sensor. Low and behold it worked just hardwire splitting the signal once.

Now I need to split the signal again, between both TCMs that could potentially be on separate battery banks. Depends on master batt switch selector. But they share a common ground, so question is, can you run a square wave pulse through a diode?? Best idea i have to isolate any drain between the 2 TCMs, lockout controller and GPS.

Only took 3 tries to get my tire size set right.. The GPS is set at 54000 pulses per mile, and shown outputting a 60mph calibration pulse to tcm. Now have RPM, prop-shaft speed, and actual boat speed in same data set.. Pretty cool for prop tuning.

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2004LB7

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You sure can run a PWM signal through a diode, the trick is the polarity of the signal vs the diode. Problem I see if you are trying to isolate the two with it is that with the correct polarity to let the signal pass is also the non isolating position too

Maybe run the signal through a transformer. Don't know what kind of current that signal need to provide but if it is just a "signal" then an audio x-former may do it. But I suspect that you will have no issues even if you directly connected it without isolation. If they share the same ground and both run at +12 volts then no current should flow between them.

Maybe you can show us your schematic
 

2004LB7

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Haha, yeah I didn't have much hope in actually seeing a schematic.

It may be a good idea to tie the two batteries positives together to balance the voltage between them and the alternators. A slight mismatch in voltage could cause current to run through the signal wire but with a larger low resistance connection between the two batteries should eliminate that.
 

kidturbo

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Well that's this issue ya have in boats. There are two engines, two separted banks of batteries, and two switch between battery banks and engines. So Port engine can use Port, Stbd, or both battery sets by turning the switch. Same thing goes with the Starboard engine..

Currently I run with both battery banks "Switched" together. This is mostly do to our Stbd alternator not charging for some reason yet to be resolved. But normally you'd try to keep the banks separated, in case you drain one listening to the stereo all day, you can still start the engines off the other bank, then recharge by flipping the switch.

So ya have a helm mounted GPS unit powered from the PORT engine harness. The signal wire from the GPS goes to a Lingenfelter pulse relay controller [on same fuse], which locks out low gear above XX MPH. It's isloated there by relays and diodes between that pulse unit and our two transmission solenoids. Next our pulse wire runs to engine compartment where it splits off to each TCM output shaft signal wire. So or TCM's thinks it's reading a reluctor wheel.. That's where I'd like to circuit protect it. If any ground interference or power drains occur, it's gonna be between those two TCM units when the battery banks are split.

Not an exact schematic, but ya get the picture..:geek:
 

Bdsankey

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Well that's this issue ya have in boats. There are two engines, two separted banks of batteries, and two switch between battery banks and engines. So Port engine can use Port, Stbd, or both battery sets by turning the switch. Same thing goes with the Starboard engine..

Currently I run with both battery banks "Switched" together. This is mostly do to our Stbd alternator not charging for some reason yet to be resolved. But normally you'd try to keep the banks separated, in case you drain one listening to the stereo all day, you can still start the engines off the other bank, then recharge by flipping the switch.

So ya have a helm mounted GPS unit powered from the PORT engine harness. The signal wire from the GPS goes to a Lingenfelter pulse relay controller [on same fuse], which locks out low gear above XX MPH. It's isloated there by relays and diodes between that pulse unit and our two transmission solenoids. Next our pulse wire runs to engine compartment where it splits off to each TCM output shaft signal wire. So or TCM's thinks it's reading a reluctor wheel.. That's where I'd like to circuit protect it. If any ground interference or power drains occur, it's gonna be between those two TCM units when the battery banks are split.

Not an exact schematic, but ya get the picture..:geek:

Kind of dirty but what about relays? If the diode method muddies you the signal you could try switched relays.
 

2004LB7

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As long as the voltage drop of the diodes isn't an issue, I think it would work. Two diodes connected together with both cathodes or anodes depending on the polarity of the signal. The signal would be fed to the center point of the diodes and each diode would send a signal to each tcm

If there was a voltage difference on the tcm and current tried to flow then the diodes would block it
 

kidturbo

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That's how I see it, but am by no means any good a complex circuitry.. However I did just hack up a 2016 Camaro throttle pedal and made one nifty ass little APPS thumb wheel for my LMM bench harness.

Trying to bring in a little Post injection action, and need to test out the hack mods on something not actually spinning first...

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2004LB7

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You know, that may be a good, if not somewhat dangerous, addition to hypermilers or those trying to eke out every last mile from their fuel. Better then the traditional cruise control for mpg
 

Chevy1925

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You know, that may be a good, if not somewhat dangerous, addition to hypermilers or those trying to eke out every last mile from their fuel. Better then the traditional cruise control for mpg

a bicycle gear selector on the throttle works well for that, i may or may not have one in the tracker :ROFLMAO:
 
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kidturbo

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Dang that's why balance rate is off.. I must have bumped the pot on the breadboard and knocked it off scale. I'm just amazed it even tries to do a bal test. The pulse pattern is very stable, so ECM jacking those values off some other factors..



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kidturbo

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Just saying

this is confusing
You should try it from this side... lol

I have a few hard coded changes to test on these LMM OS that aren't listed in EFIlive. Mostly related to getting Post1 injection pulse to activated. Goal is possibly add some fuel late and below 2k, to see if can overcome the heat loss in the pipes, and help our spool RPM.

Rather than just go trial by fire, I resurrected the old bench harness we originally used to fire em up on the stands in fall of 18. Along with a spare ECM, set of old injector solenoids, and a little Arduio board crank/cam simulator box, I can load any tune, then run the shit out of it without ever starting an engine. So if these new calibrations are screwed up, it doesn't send you the text via hole in a piston..

If I want to see how these act at WOT, 5800RPM, with 55lbs boost, and say a 250F IAT issue, just set this jig up, then adjust IAT2 input voltage to reflect extreme air temps under whatever conditions. In this case, I found it actually only adds timing, but doesn't cut fuel as expected. So now I go figure out how and why, then reload tune and test again. Plus you can do it all from the recliner sipping a cool drink..