DIYEFI.org temporary test mule (No 56k)

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Fred
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Re: DIYEFI.org temporary test mule (No 56k)

Post by Fred »

The injectors are driven by a pair of these http://www.sanken-ele.co.jp/en/prod/sem ... a460ce.pdf

Which have built in diodes for protection. There are no external components, just direct drive by those chips and let the injector do as it pleases to the extent allowed by the internal clamps.

One of the to220 devices appears to be the controller for the heater circuit of the O2 sensor, but I haven't confirmed that yet.

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Re: DIYEFI.org temporary test mule (No 56k)

Post by Fred »

The caps on the VR lines were "greencaps" btw.

Knock :

Comes in through a 220pF ceramic disk cap to ground, has a (y, y, r, br, 1%(br)) resistor to ground 4420 Ohm? then a 2.2k resistor inline which feeds two greencaps, one to ground of 3300pF and one to an IC pin of 4700pF There is a diode from the output of the capacitor to ground to prevent the signal from going negative.

So, it's provided with an input impedance and input capacitance for smoothing, then a first order low pass filter with pure capacitive coupling to the IC. Interesting.

There are also two separate power feeds to the box and at least 2 separate grounds.

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Re: DIYEFI.org temporary test mule (No 56k)

Post by Fred »

Innards as discussed above :

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The writing you can see identifies the critical sensor signals at the processed ready for reading stage. By connecting my TA card to those points and a few others I can datalog the state of the engine. I could even take it a bit further and write some special firmware to record and datalog the duty cycle of the injector outputs too. I'll probably hold off doing anything till I have a spare ECU to hack up so I can plug and unplug it easily. I'll probably also wait till I have a basic serial app and some decent comms happening. After that the next step is to run it fuel only, exciting stuff but a lot of work to do before then!

Fred.
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Re: DIYEFI.org temporary test mule (No 56k)

Post by jharvey »

Hmmm, looks like a large resistor next door to the injector driver. How close to 70R is it?
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Re: DIYEFI.org temporary test mule (No 56k)

Post by Fred »

The injector drivers are shown in this picture :

http://i260.photobucket.com/albums/ii15 ... 0_8643.jpg

They are SIL chips. You can see the four thickish traces leading towards the connector from them.

I think one of those to220 devices is the switch for the O2 heater. Not sure about the other.

The resistor is pretty far from 70 Ohm ;-) 0.1 Ohm actually. It's for coupling two grounds together and possibly current sensing I guess. I didn't pay it much attention really. I was looking for ways we could change our design to benefit from Toyota's wisdom and specific functionality and how it was implemented and how to connect to it. I found all of those things and am now ready to do on car testing in the near future, even if it's only basic stuff. Mission accomplished :-)

Fred.
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Re: DIYEFI.org temporary test mule (No 56k)

Post by Fred »

Bump from the dead, I don't know who wrote this thread, but he documented his findings very well ;-)
Fred wrote:There is one IC each for G1 and G2. The NE signal goes through a 751 smd resistor to one of those ICs but not the other. The matching pin on the other is grounded with a decoupling capacitor. The one that the NE signal goes to has two pins out to the CPU and the other only has one. The one that is used on the first is NC on the second. The ones that match are also joined together I guess in something like "wired OR mode".

What this says to me is that each of these ICs is a dual conditioning chip. The part numbers are SE077 9P 09

I guess this means that to run a toyota engine properly, 3 VR conditioning chips are needed on board even though only two signals make it to the CPU.

Hey Jared, best you add another LM1815 in there for all the toyota fans :-) This can be reused by others for a VSS input.
Marcos, Jared, others, what are your thoughts here. For this very common 24+2 distributor (which I am about to try to run) if using only two max chips, we can only run it as 24+1 which allows COP/CNP/Sequential use, but has slow starting. If a third max chip was supplied, with the output connected together for one pair of them, we could run only wasted spark/semi sequential and start twice as quickly. With 3 chips and 3 MCU pins (not going to happen) we could run with fast starting and dual sync. I just thought of a way to do it with only one main T port input, and an accessory pin, that would give the best of both worlds, it would still require a third max chip. I guess the question is, should we make people add this third chip and hook up this extra normal pin as a mod for the nicer decoder type. I guess the answer is yes, because to add a third chip to the PCB design for what amounts to 10% of the user base is not a good idea.

OK, off to write an N + 1 decoder! :-)

Fred.
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Re: DIYEFI.org temporary test mule (No 56k)

Post by jharvey »

I'm tempted to say connector card. That's what it was intended for. A fairly quick hack could be made to get you something quick and low cost now-ish. Attempted to use the two signals to capture the 3 signals sounds complicated and potentially problematic. Even if you get it working well now, what happens if it gets some noise, or a slightly bad connection, ect. I'm tempted to encourage one general max chip design, such that problem diagnostics is a bit more simplified. Test the heck out of that one design, and use it everywhere.

I can probably wipe up a board for one of the headers if we need it. Is the need right now, for a spin1, or is the need for the next spin?
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Re: DIYEFI.org temporary test mule (No 56k)

Post by Fred »

Don't worry about it, this would be a connector card thing OR mod to Puma AND connector card thing, and only for maz, toy, hon cars, and only for those that use this signal type, and only if they wanted sequential/COP AND faster starting. Kinda niche, but it's nice that I figured out how to do it properly with only two timer pins and one normal gp input pin.

Trying to use the two chips to monitor 3 signals is not at all the correct approach... due to the shared ground and AC signal it can not really be done at all.

Fred.
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