Not a car... CX500TC

[abecedarian]

80 degree V-2, EFI and turbocharged to >17 PSI boost... from the factory.
CX500TC- not much else to say.

[AndreyB]

How can I convince you to solder rusEfi i-o boards and start this engine with rusEfi?

I can promise 24/7 live support

PS: where are you geographically?

[abecedarian]

I'm in the south... of California, USA.

To convince me to use this... hmm. I'd need the MCU and other boards, and knowledge it could handle fueling the bike.
So it would need to handle the cam / NE sensors (VR type) and accurately control two low-Z 330 cc/min injectors.


I'm not too worried about ignition yet since the EFI system is separate from the spark system on my bike, and I haven't found a system able to handle ignition on this, yet. Honda had a strange way of doing it with this, it seems: 1 tooth on the flywheel triggers ignition for each cylinder, independently, and manifold vacuum / pressure controls advance / retard, basically, the 'tooth' on the flywheel generates the primary voltage that sets up for spark and by controlling the gate threshold on the thyristors triggering the ignition coils- high vacuum = low voltage = more advance and boost = higher voltage = less advance / ignition retard, a pressure sensor actually fires the plugs.


Though I do have a 32-1 trigger fabricated and ready to install, but yet again, it's VR based. It's intended for whatever 'final' system I install so that ignition can be controlled.

Please disregard the fact the missing tooth isn't missing yet.



I have two VR sensors mounted, which I can pick whichever one to use- they are 80 degrees separated which corresponds to the cylinder separation.

[AndreyB]

If you would get the MCU I can send you our VR board

Or we can exchange stm32f4+VR pcb+24/7 support for the Freescale board

[abecedarian]

First problem I see is my requirement for supporting low-Z injectors.

Remember, it has to support a 500cc engine breathing up to 1300 cc's of air... and the fuel to go along with that... with two injectors.
High-Z injectors are mostly out since the opening / closing times are too slow to support stable idle particularly with the total flow I need at high RPM / boost.

[AndreyB]

I've missed the low-Z part, my bad.

What are the stock injectors - you said it was EFI from the factory, Low-Z does it require PWM or is it the same thing as High-Z with a resistor? I guess I need an elaboration on what difference does low-Z make or what kind of performance (in absolute times) you would need, If the stock ECU did it 20 years ago I must be capable of doing it with x10 times faster MCU?

[abecedarian]

I've missed the low-Z part, my bad.

What are the stock injectors - you said it was EFI from the factory, Low-Z does it require PWM or is it the same thing as High-Z with a resistor? I guess I need an elaboration on what difference does low-Z make or what kind of performance (in absolute times) you would need, If the stock ECU did it 20 years ago I must be capable of doing it with x10 times faster MCU?

My stock injector 'impedence' is 1-3 ohm; they open and close faster than high-impedance injectors of similar flow rating.
Maybe better known as "peak and hold" is what my injectors are, and you're supporting "saturated".
At 10000 RPM, these injectors are near 100% duty cycle.

High-Z injectors with similar flow rating won't open / close fast enough to give accurate fueling near idle.
High-Z injectors with similar flow rating won't open / close fast enough to give accurate fueling at WOT.

The bike runs rich most of the time and fouls plugs within a few 1000 miles as it is.

Making sense yet?

Asking for more means, likely, going to a staged fuel injection system. Are you ready for that?

[AndreyB]

No idea what staged injection is but let's do one thing at a time.

So, are these controlled via PWM (multiple on/off signals per cycle) or same one open one close per cycle as on the high-Z? So, is the difference between low & high just in the driver circuit, or is something different from the point of control LOGIC?

If the issue is simply with adjusting the analog side, let's see how we should adjust the analog side

[abecedarian]

No idea what staged injection is but let's do one thing at a time.

So, are these controlled via PWM (multiple on/off signals per cycle) or same one open one close per cycle as on the high-Z? So, is the difference between low & high just in the driver circuit, or is something different from the point of control LOGIC?

If the issue is simply with adjusting the analog side, let's see how we should adjust the analog side

My injectors, because of their low impedance, draw a few amps when opening, hence allowing them to open quickly, but only require a small current to stay open. Hence, they open and close faster than high-impedance injectors. You could PWM and tease my injectors but that only makes them behave like high-Z injectors.

[abecedarian]

And 'staged' injection would be something like where one set of injectors handles "low speed" fueling, and additional injector(s) provide fuel for high-speed use.

[AndreyB]

ok, sounds like lowZ is same as highZ from the software side since no pwm within a cycle, just special output circurtry

[kb1gtt]

JBperf has a nice low Z drive board here http://www.jbperf.com/p&h_board/v2_0_1.html For most of JBperf's designs, I have good things to say, this is one of those boards where I have good things to say. He did a good job making sure to select the correct component for the task.

[AndreyB]

the mosfet on our 6 channel output is capable of 12A, would it work? Or do we need a chip with explicit P&H feature?

[Sergey89]

In many JDM vehicles Low-Z injectors are driven with additional resistors. So I think that at this point this solution can be used.

the mosfet on our 6 channel output is capable of 12A, would it work? Or do we need a chip with explicit P&H feature?

Low-Z injectors requires current limiting at the hold state.

[AndreyB]

So I think that at this point this solution can be used.

I think the topic starter was looking for a final solution, including higher RPM.

Are there any peak-and-hold fully integrated chips we like?

[kb1gtt]

I see several options, one is to buy it. If price is a concern, then we have two other options. One options is to use one MOSFET and PWM for the hold. I have some suggested approach on how to get a good pulse train as you drop from peak to hold with an embedded platform. I'm not sure how well this will work thermally, as it might dump lots of heat into the MOSFET. Which leads us to plan B, which would be to use two channels, one channel with a series resistor which will dissipate the heat away from the ECU and would operate as the hold current, the second channel as a direct to path to GND which would be the peak drive. For two injectors you would need a total of 4 channels.

I think it's safe to assume that no one wants to spend the extra $ if they don't want to, and I think Kurt isn't in a huge rush, so we can take some time to do this a bit more experimentally. I also suspect that we should go right for Plan B and use the resistor option. Kurt, can you tell us your injector resistance? You can measure it directly with a multi meter. I think it's like 3 or 4 ohms, it could be as low as 2 ohms. We'll need to get a resistor that gets the total resistance close to 12 ohms. That resistor will draw about 10 watts at a 1 amp draw. Something like this would do OK. http://octopart.com/rh05010r00fe02-vishay-146878 Hmmm, I should check the energy efficiency of plan A, we might save some alternator loading if we go Plan A.

[abecedarian]

Stock injectors are 1-3 ohm per factory manual but I'm not entirely locked to factory injectors- mine have been cleaned and flow checked and are at approximately 80% flow rating so not really serviceable for me and replacements are near impossible to get a good set.

I've got some things to work out still so, I'll probably be changing to a different injector and will have to work out fuel pressure corrections and such. This might also mean a change to high-impedance injectors. Since my stocks were rated 330 cc/min, I'm investigating whether 370 cc/min injectors will flow well enough for low RPM use. If not, as mentioned, another option is staging injectors and using a pair of 155 cc/min for low speed and bringing a pair of 250 cc/min online to supplement the others, but significantly complicates things.

[abecedarian]

Well, since I mentioned CMC connectors...

2_24_2014_render_B.png

3 SPI brought to the plug... might change one or two out for CANBUS.
Possibility of bringing one LIN to the plug, but I'm struggling to validate the need.

Still have to route a few analog sensors on the board:
,,, intake temp, throttle position, coolant temp and manifold pressure....
... and the other crap too.