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11-10-2015, 12:14 PM | #21 |
Not Yet Wild
Join Date: Apr 2013
Posts: 30
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Re: Fuel Injected TXT 295cc w/ LS2 Coils
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11-10-2015, 12:48 PM | #22 |
Gone Wild
Join Date: Oct 2010
Posts: 6,730
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Re: Fuel Injected TXT 295cc w/ LS2 Coils
Can you tell me what it is about the fuel delivery portion of the Speeduino project that is "far more advanced"? You don't need to add complexity for the sake of fuel delivery. I have MAP, IAT, TPS, AFR sensors, multiple fuel maps, startup enrichment, acceleration enrichment, min/max protection, etc...
I am not running parallel processors. I have 2 independent processors, with the sensors wired in parallel to each of them. This was one of the steps I took to be able to achieve deterministic timing. As for the missing tooth/hall setup, I can only imagine that the firing of the injector is based off of a specific tooth position, not all of them. That makes the only important tooth, the last one before injection starts. Why is it specifically that you think a single trigger can't be used? The only reason I can come up with is because of a variation in processing time. The engine speed can't change fast enough within one revolution to have appreciable effect. I'm not suggesting that we should avoid any additional information as it would burden the processor. The additional information(MAP, TPS, IAT, AFR) should be input to the controller during the main program loop. ~1msec. I have already achieved deterministic timing with both controllers. It is less a function of the controller, and more a function of the speed/accuracy/repeatability of the Schmitt trigger, and the efficiency of the code I have written. I'm also not trying to say that automakers are just too lazy or not smart enough to engineer "deterministic timing". I'm just saying that I don't believe it is necessary to have a toothed wheel. That will reduce complexity and cost for the end user. |
11-10-2015, 02:39 PM | #23 |
Not Yet Wild
Join Date: Jun 2009
Location: Washington
Posts: 57
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Re: Fuel Injected TXT 295cc w/ LS2 Coils
I've been over on the Speeduino sight all day - I don't know if I missed it or not, but I'm wondering if there is a way to incorporate a knock sensor into the mix. I know nothing of writing code etc.. but now I want to learn.
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11-10-2015, 02:57 PM | #24 |
Gone Wild
Join Date: Oct 2010
Posts: 6,730
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Re: Fuel Injected TXT 295cc w/ LS2 Coils
Yes. A knock sensor can be hooked up to the controller analog input and code written to retard the timing if the engine is detonating.
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11-10-2015, 03:57 PM | #25 | |
Not Yet Wild
Join Date: Apr 2013
Posts: 30
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Re: Fuel Injected TXT 295cc w/ LS2 Coils
Quote:
As to why the Speeduino is more advanced than your setup, it is a long list of functionality, but to sum it up simply, it does fuel and ignition timing. When do you think you will have your cart back up and running? |
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11-10-2015, 04:17 PM | #26 | |
Gone Wild
Join Date: Oct 2010
Posts: 6,730
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Re: Fuel Injected TXT 295cc w/ LS2 Coils
Quote:
My sensor will trigger at about 10° BTDC of cylinder number 2.(This leaves room for timing advance) It will calculate how long it needs to wait until it reaches the dwell angle, then start the dwell, and time out. At the same time it will do the same thing for cylinder number 1, 90° further. Your sensor is sensing every tooth and running an interrupt every occurrence. It looks to see if the crankangle is less than the programmed ignition timing value, calculates the amount of time until it will reach the dwell angle, waits that amount of time, then it starts the dwell. The main difference is that you need to update the ignitionstarttime on every tooth because of program latency. I do not have to do that. That's the difference between trying to execute several thousand lines of code, with numerous function calls and many interrupts, and executing 75 lines of code with one single interrupt. Is that about how it works, or am I missing something? The motor is currently on a test stand and will probably not be back in the cart until spring. You will find that you didn't happen to stumble on a forum full of dummies. There is probably an expert on just about any subject, lurking in the shadows. These guys may play with golf carts for fun, but they are extremely smart in their area of expertise. |
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11-11-2015, 11:15 AM | #27 | |||
Not Yet Wild
Join Date: Apr 2013
Posts: 30
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Re: Fuel Injected TXT 295cc w/ LS2 Coils
Let's star from the bottom, shall we:
Quote:
Every time the toothed wheel triggers the interrupt, it updates the current crank angle. This crank angle is more accurate the more teeth there are on the missing tooth wheel. The ignition and fuel timing are constantly updated using this information. That's what you don't seem to get - engines under load are not linear in their response like they are on your test stand. You may be able to achieve some semblance of ignition timing on your test stand with a single trigger, but in your cart you will never match the performance of missing tooth wheel setup. Period. Remember the yard stick metaphor I used in my last post? As to code latency, you still don't seem to grasp the power of a 16,000,000Hz processor - even 10,000 lines of code consuming 5 instructions per line is only consuming 1/32 of the processor in a second - still lot's of processor capacity left. Even if you use a 4Ghz Intel i7 (4,000,000,000hz btw) and did your timing in 75 lines along with your single trigger setup, you still would never match the ignition timing accuracy of a missing tooth setup and a little ol' 16Mhz Arduino. Quote:
Quote:
Bottom line, my cart is up and running great with both fuel and ignition timing and you are still in test phase. My thread was about my completed cart, so I ask that going forward we continue our discussion on your thread, as it seems to pertain more to your build than my running cart. Thank you Louis |
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11-11-2015, 09:22 PM | #28 | |
Gone Wild
Join Date: Oct 2010
Posts: 6,730
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Re: Fuel Injected TXT 295cc w/ LS2 Coils
Quote:
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11-11-2015, 10:10 PM | #29 | |
Not Yet Wild
Join Date: Apr 2013
Posts: 30
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Re: Fuel Injected TXT 295cc w/ LS2 Coils
Quote:
Louis |
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11-11-2015, 10:36 PM | #30 | |
Gone Wild
Join Date: Oct 2010
Posts: 6,730
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Re: Fuel Injected TXT 295cc w/ LS2 Coils
Quote:
Efficient coding has nothing to do with processor speed. Even the fastest processors can't compensate for inefficient coding. If you'd like to learn something, I can help. |
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