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Originally Posted by y8s
(Post 749148)
Oh hai.
So I have run into what may be an issue with the alternator control circuit: SERIOUS BELT SQUEAL. At startup. I suspect the circuit is saying "Scotty, Gimme that power!" since voltage drops and the circuit engages the alternator thus increasing the load seen by the belt/engine during cranking. So I want to add a transitor inside the megasquirt to address this. will switching the ground of the circuit through a TIP120 cause problems? Would I be better off switching out the output wire or something else? I have a TIP120 already wired in the megasquirt that switches to ground and I was just going to use that. Thanks nerdy bros. |
I am convinced enough to try the fix--it shouldn't harm anything.
I suspect this problem because of the way the car starts up. It struggles against something while the squeal continues and then once it stops, the engine revs freely as if it were released from the shackles of oppression. Also voltage remains a couple volts lower during the squeal. When the squealing stops, voltage ramps up to 14.4 and RPM surges upward a few hundred RPM briefly. Load also sits about 6-8 kPa higher than no-squeal idle. my morning datalogs show the same recurring symptoms frequently. |
Loose belt.
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does the stock ECU engage the alternator at startup?
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I can tell you that my own circuit ignores RPM but I don't have that symptom.
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Originally Posted by JasonC SBB
(Post 749276)
Loose belt.
My car had the exact same symptoms and a new tight belt sorted it. But IDK, I'm comparing apples with oranges I suspect. Still without wanting to sound like I'm teaching you to suck eggs, have you checked the belt tension/quality. |
I put a new belt on a few years ago when I had the Hydra or Adaptronic or something and a similar or the same circuit. It is TIGHT like your daughter.
It started squealing about a month later. |
Originally Posted by y8s
(Post 749484)
I put a new belt on a few years ago when I had the Hydra or Adaptronic or something and a similar or the same circuit. It is TIGHT like your daughter.
It started squealing about a month later. But wait, if it didn't do it initially why does that make it the controllers fault? Maybe the belt is all shiny'ed up? |
Matt,
I really like the idea of being able to turn it on and off.... But I agree, it's not really your problem. I've been running a circuit (which admittedly, doesn't ask for as much out of the alternator - but I DO have a 1200W stereo on there, which I guess isn't powered at start up) that ignores RPM for.... like 5 years? I've had a couple bouts with belt squeal, yes generally on start up, and.... I've never resorted to electronics to clean it up. Tightening the belt helps. Then again, you'll probably get crank pulley wobble with all that tension. :-P |
Originally Posted by y8s
(Post 749484)
I put a new belt on a few years ago when I had the Hydra or Adaptronic or something and a similar or the same circuit. It is TIGHT like your daughter.
It started squealing about a month later. |
1 Attachment(s)
beats me, I would rather build circuits. :)
incidentally, aside from an automotive style relay that switches out the alternator control wire, what's the proper NPN/PNP transistor circuit to use for something like this? obviously I can't put a transistor on the 12V or gnd line to the control circuit because it will jack up the battery voltage reading so it has to go on the output. like this only not +12, but the alternator circuit output and remove the LED and just run a new output wire off that location? the grounding output of the MS CPU would go to the base. https://www.miataturbo.net/attachmen...ine=1311271577 |
What problem are you trying to solve?
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just want to disable the alternator control at will via a megasquirt output.
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So to resurrect this thread one more time, I've got a 99 NB, MicroSquirt, no factory ECU and have a Mopar voltage regulator. I have the blue wire hooked to 12V+ switched and green wire to the 1O grey/red and it does not charge. The case of the VR is grounded so the questions are"
1: should the green VR wire go to 1T instead (grey)? 2: does the wire not hooked to the green VR wire (either 1T or 1O) get 12V+ switched? 3: Penelope Cruz or Selma Hayek? |
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