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Old 05-20-2008, 08:41 PM   #111 (permalink)
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DCB: the Zener identified as "Digital Pin 14" goes to analog #0. Is the label just incorrect?

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Old 05-20-2008, 08:49 PM   #112 (permalink)
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sameo sameo, they are multi-purpose pins.
digital pin 14 is analog in 0
digital pin 15 is analog in 1
digital pin 16 is analog in 2
digital pin 17 is analog in 3
digital pin 18 is analog in 4
digital pin 19 is analog in 5
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Old 05-20-2008, 09:10 PM   #113 (permalink)
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Quote:
Originally Posted by dcb View Post
the max cpu % was less than 25 and free mem stayed at 158 (as expected). So the interrupt handlers are pretty tight, and we can entertain upping the refresh rate to .5 seconds.
That's good news. .5 sec doesn't sound like a lot, but when you're looking for "instant" feedback, it is.
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Old 05-20-2008, 10:53 PM   #114 (permalink)
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Quote:
Originally Posted by dcb View Post
15 injector pulses/second, ~80,000 uS .

15 * 60 * 2 = 1800 RPM, which is about what I saw on the tach.
I'm not sure what the 2 is doing? Unless you're saying they fire every other revolution. I was under the impression that the saturn mpfi systems fire all injectors at the same time, and that they fire once per revolution. (i could see them fire once every other revolution if they were independently controlled). If yours are controlled independently of one another, then that makes perfect sense, and is a change from the earlier model years..

I'm seeing more than double your pulses at just a few hundred RPMs higher, and less than half of your uS..

Yes, mine is an MPFI.

You still have your resistor next to the guino, and not at the injector right? Maybe I do have connection issues..
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Old 05-20-2008, 11:39 PM   #115 (permalink)
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Hmm, my injectors had different colored control wires, so I assumed they fired when the intake valve was open. So the *2 was really *4 injectors/2 revolutions.

resistor is on the guino, will likely stay there.

I'm just guessing on the saturn value. You posted a 267,857,142.86 figure for the 21lb injectors and that was close enough to my guesstimates that I went with it. But if we really do have variable fuel pressure then we can only make a guess on the flow and try and true it up on fillup.

Anyway, maybe your mpfi squirts two cylinders at a time and mine just one? Is there a saturn expert in the house?
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Old 05-21-2008, 12:09 AM   #116 (permalink)
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Injectors factoids

Throttle Body Injection (TBI) is not always timed to every other revolution of the engine.

Most domestic OE production EFI systems use an ECU with 12 volt Saturated Circuit drivers.
An injector operating on a saturated circuit driver typically has a reaction time of 1 milliseconds.

(Saturated Circuit Driver) Injectors are 10 to 16 ohms for identification purposes.


The very conservative approach Ford uses to calculate the injector size for the factory engine uses the O.E. typically safe 0.80 duty cycle limit.

So a 19 lb/hr Ford rating is at 80% duty cycle.

Some Muti Port Injection (MPI) use:
batch fire,
some use bank fire,
some use individual or sequencial fire. These all fire every other revolution.

But almost all (MPI) are timed to the engine.
I say almost because Chevy has a CPI Vortex V6 and i don't know how it works. It looks like one injector with 6 nozzles.

Last edited by diesel_john; 06-16-2008 at 09:45 AM.. Reason: changed:Throttle Body Injection (TBI) is not always timed to every other revolution of the engine.
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Old 05-21-2008, 12:33 AM   #117 (permalink)
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Quote:
Originally Posted by diesel_john View Post
Throttle Body Injection (TBI) is not timed to the engine.
Hmm... this data was from a tbi metro, you can see inj count going through the gears then stabilizing in 5th gear to be proportional to vehicle speed (vss count). I believe that at least some TBIs, while not critically timed with valve position, do use an injector signal proportional to rpm. In fact the metro seems to fire 3 times per 2 revolutions. When we hit the 38 in inJcount we have just shifted to 5th gear. Shifts are at 40->34, 51->37, 50->42,49->38 . Counts are total for one second.
Code:
byte vssCount[]={ 0 ,2, 6,10,13,15,18,20,22,25,25,27,28,29,28,28,28,26,26,25,24,23,24,23,24,24,24,24}; 
byte injCount[]={37,40,34,51,37,43,48,50,42,46,49,38,37,39,38,37,37,36,34,33,32,32,31,32,31,32,32,33}; 
unsigned long injHiMS[]={69002,117777,101972,138435,148117,174988,98775,164693,165873,176190,113628,148571,120702,58276,39501,37891,38435,37369,37006,37142,39433,62879,71179,71995,77074,95215,86281,75419};
Note, this was gathered with a laptop running sound recorder, I suppose one could use the same technique in lieu of a real oscilloscope if the signals aren't making sense.
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Old 05-21-2008, 12:51 AM   #118 (permalink)
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Saturns up to 95 are peak and hold injector types.
96 and up are saturated. I haven't seen anything that says the injectors on the saturns are controlled in pairs, or that they ever went to sequential fire.

If the injectors are rated at 80% duty cycle, then that would change my microsecondspergallon calibration by a bit..

I dunno, maybe our two saturns are different enough to not even try to compare.. atleast our VSS signals are the same.
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Old 05-21-2008, 01:05 AM   #119 (permalink)
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Ah, after searching for fancy terms like "sequential" I found this:

http://www.saturnfans.com/forums/sho...9&postcount=10

91-95 - OBD1 - no cam signal, all fuel injectiors fire at the same time
96-02 - OBD2 - with cam signal, injectiors fire in order, this is sequential
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Old 05-21-2008, 01:32 AM   #120 (permalink)
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Quote:
Originally Posted by dcb View Post
Ah, after searching for fancy terms like "sequential" I found this:

http://www.saturnfans.com/forums/sho...9&postcount=10

91-95 - OBD1 - no cam signal, all fuel injectiors fire at the same time
96-02 - OBD2 - with cam signal, injectiors fire in order, this is sequential
i swear... i was coming back here to paste those exact lines..
that's the only time i've seen the distinction being made. over and over on saturnfans, people say the injectors fire at the same time.

now i guess i need to go back and check some things.. i'm mpfi, but since i'm running in batch, it's just like one big tbi injector firing.. that's kind of the assumption i made when i was coming up with the numbers I'd expect to see. My injector count still checks out at 36 or whatever at 60mph, but maybe my 19lb microseconds per gal, and the one i threw together for your 21lb, are way off..

maybe tomorrow i can get this sorted out..

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