:::RHMT::: Real Home Made Turbo
General Category => Engine Management => Topic started by: danz on September 01, 2014, 07:56:29 PM
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What are the actual components in the OBD1 Honda ecu that drive the injectors?
I googled it and came up with these three fuckers. But why three, when there are 4 injectors? Do not understand that. Looking to verify. The google result called them transistors. Over my head at this point, not the most in depth electronics guy.
Reason for asking is to add additional cooling to that area. Heat sink, fan, case fan, external ducting negative pressure stuff etc.
(https://lh3.googleusercontent.com/-UNezgJlc1C4/VAUG7tKT45I/AAAAAAAAHNc/SkaYYJZBeeM/s800/000_0153%25202.JPG)
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Actually 2 of the 3 are the injector drivers, they'll the 2 closest to the edge labeled "STA460C". They're a sort of dual transistor package with various resistors & diodes inside. The specs show they can handle 3 amps per channel, and you only need to actively cool them with 2 amps or more per channel - in other words, dual saturated injectors per cylinder. The 3rd black thing controls solenoids or something, totally unrelated to the injectors.
Cool fact: they use a 5 volt TTL signal for the input, so you can tie into that input to drive one of the cheaper P&H injector driver boards designed for Megasquirt. Most would let you get away with 3 injectors per channel (2 if they're older big fat solenoid designs).
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QM1 and QM2 as Hiprofile stated handle 2 injectors each.
QM3 looks to handle 4 circuits as well
-something for A/C
-main relay (I've had no fuel pump require a new QM3)
-Fan control
-O2 Heater control
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A little something I whipped up a while back:
(https://realhomemadeturbo.com/forum/proxy.php?request=http%3A%2F%2Fimg692.imageshack.us%2Fimg692%2F4382%2Finjectordriverv11obd1ho.jpg&hash=c3aec50281c77979d476f46cd1e77c94e8746d61)
IIRC the picture shows the rough location for the initial outlet for the signals if you want to intercept them for a 5v TTL injector driver. Kinda useless since two sets of huge saturated injectors are so damned cheap...
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Awesome guys thats perfect information. Good to know. Hmm the idea of swapping other ones in intrigues me, but only if the heat sink and fan idea fails.
I want to drill some holes in the case around there, and build some aluminium or copper arms and fins so the air runs directly over the fins. The case will have a simple CPU fan pulling a vacuum on the ecu case, so the air will enter the holes I drill and pull over the fins I fab up.
At least, thats the plan.
As you guessed it, HiProfile, I want to run 2 sets of injectors. Hehe. But I am thinking, perhaps to run some way smaller injectors, and use a separate fuel system to run a PWM water meth. To scale by adjusting injector size to the main fuel injector. IE, 800cc mains, 80cc slaves, 10% w/m injection give or take.
Any ideas about this crazy talk?
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Awesome guys thats perfect information. Good to know. Hmm the idea of swapping other ones in intrigues me, but only if the heat sink and fan idea fails.
I want to drill some holes in the case around there, and build some aluminium or copper arms and fins so the air runs directly over the fins. The case will have a simple CPU fan pulling a vacuum on the ecu case, so the air will enter the holes I drill and pull over the fins I fab up.
At least, thats the plan.
As you guessed it, HiProfile, I want to run 2 sets of injectors. Hehe. But I am thinking, perhaps to run some way smaller injectors, and use a separate fuel system to run a PWM water meth. To scale by adjusting injector size to the main fuel injector. IE, 800cc mains, 80cc slaves, 10% w/m injection give or take.
Any ideas about this crazy talk?
This is intriguing, more info. please
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I think the smallest I've seen is 160 or 180cc, but that's "modern" technology that can take more than 60PSI. Talk to David Blundell, he has tried active cooling for dual injectors. I also know Jeff Evans has tried an ecu with doubled-up transistors by some obscure shop of old, making 8 transistors (4 black components) total. You can still buy those parts off ebay IIRC. Most of this black art was given up when ID1000's came to be, and ID2000's sealed their fate.
One thing I could see working is using some piggyback controller that intercepts and modifies the injector pulse. You can tie that into the injector wires and run the piggyback's output to the meth injectors. That way you can reduce the duty drastically (or completely) during vacuum. If there was something that could reduce a set amount off a PWM signal (e.g. take 5ms off the entire pulse) then you'd really be set. An FMU may also help ramp up the injection rate with boost.
I think one thing you'll want to do is use a relay controlled by an ecu GPO or a hobbs switch which enables the meth injectors. That way they don't start spraying until you want them to. The relay would just cut off the positive power wires, and wouldn't harm the signals to the meth injectors when turned on, nor would it affect the main injectors.
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I was thinking to use the ECU to control a relay that controls +12v to the injector pig tail. So it only comes on at a certain point.
Additional fuel scaling can be taken care of by fuel pressure. So 180cc injectors at 20psi, instead of 40/60psi etc.
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I was thinking about the fuel pressure as well, but in most cases atomization will suffer at just 20psi. I physically see the spray pattern on injectors weekly, and 20psi will be too low even with a tiny injector.
The only thing I could think of is some sort of PLC that can react fast enough between injector pulses. It could use the injector pulses as an input, then reduce the pulse as needed to fire the meth injector. The only real problem with this is now it's another project in my head I'd love to build but have no time time to do so...lol.
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I will try it and let you know how it works.
The other way is to use one or two instead of four injectors.
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A little something I whipped up a while back:
(https://realhomemadeturbo.com/forum/proxy.php?request=http%3A%2F%2Fimg692.imageshack.us%2Fimg692%2F4382%2Finjectordriverv11obd1ho.jpg&hash=c3aec50281c77979d476f46cd1e77c94e8746d61)
IIRC the picture shows the rough location for the initial outlet for the signals if you want to intercept them for a 5v TTL injector driver. Kinda useless since two sets of huge saturated injectors are so damned cheap...
This interests me, I always thought about running my v8 truck on a Honda ecu and doing a wasted spark type setup so the distributor could run 8 cylinders and the injectors firing in pairs. Semi Sequential? Lol
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Now that you mention that, it could work. Batch fire controls 4 injector channels firing each twice for half the required duty cycle. Wasted spark on a 4-cyl ecu would work to fire an 8-cyl motor, so it would be more advanced than most basic Megasquirt instals.
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And even then, you can plug your injectors in wrong and the engine will still run pretty damn decently. So meh, it should work fine. Should even be able to rig up some super ghetto T spark plug wires, that split and T to make for 8 leads. Lol. Actually sounds incredibly easy.