ridgeracer
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posted July 16, 2007 02:31 PM
Cam timing question
As part of the ECU project I need to know when the cam sensor tab on the end of the cam is directly in from of the cam sensor what is the position of the crank/cams.
Is it at cylinder 1 TDC? If so is the next down stroke an intake or power stroke?
OR
When the cam tab is in front of the sensor what is the position of the nearest crank timing wheel tab in relation to the crank sensor? Is it also directly in front of? Just past or just approaching?
Inquiring minds want to know.
   
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ridgeracer
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posted July 19, 2007 11:28 AM
bump
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VincentHill
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posted July 19, 2007 12:10 PM
At least I understand the question! You want someone with an assembled engine (WHich mine is not) to turn the engine over until the cam sensor is in position to trigger the sensor. Then look at the other side of the engine to see what Position the ignition rotor is in. DO this as many time as you can see different results until the first result is seen again! (Most likely 2 times)
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ridgeracer
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posted July 19, 2007 12:28 PM
The first part is correct but you only need to turn it far enough to see if its a power stroke, both intake and exhaust valves are closed on cylinder 1, or an intake stroke in which case the intake valves on 1 will open. You should be able to tell by just looking to see where the intake lobes are on cyl 1 when the cam nub is centered on the sensor.
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VincentHill
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posted July 20, 2007 07:41 AM
The reason I said 2 revolutions is the difference between Cam speed and Crankshaft speed is 2 Revolutions to 1 and I thought you wanted to know what the Crank Rotor position would be through a complete cycle.
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Made History @ Daytona and still one fast old man!!
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ridgeracer
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posted July 20, 2007 07:58 AM
What I'm trying to do is make a bike simulator to plug the ECU into to fake it into thinking it is on the bike. I know that there is one cam pulse for every 16 crank pulses but what I don't know is do they pulse together or does the cam slightly lead or lag the crank pulse.
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entropy
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posted July 20, 2007 08:33 AM
RR & Vince,
I will be pulling my motor down very soon and I will get the info RR needs.
(time to do another experiment  )
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VincentHill
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posted July 20, 2007 12:27 PM
Good Deal Karl,
I just got a little package from CP today! BUT I have some more machinning to do on a wheel hub and a few spacers so that they will properly fit a ZX12R BEFORE I can start to re-assemble my engine. Where do I send the check for the Oil squirters ?
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Made History @ Daytona and still one fast old man!!
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entropy
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posted July 20, 2007 05:50 PM
vince,
the jets are a present, from my house to yours!
Just get that motor going and i'll be a happy man to see you running it again, yep!
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rgeorge
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posted July 20, 2007 08:00 PM
 Edited By: rgeorge on 20 Jul 2007 21:04
RR, I think this is what you're looking for. 
note: my DAQ input limit was +- 10v. The actual peaks would have been slightly higher.
polarity:
crank sensor
yellow wire = AI0 +
black wire = AI0 -
cam sensor
brown wire = AI1 +
yellow wire = AI1 - (weird but thats the testing procedure from the service manual)
If you want the raw data collected pm me your email.
Rob
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ridgeracer
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posted July 21, 2007 05:56 AM
Thanks Rob, thats even better than what I was looking for. Now I know exactly the waveform it's expecting.
It is weird to have the two sensors use opposite polarities but it does have the apparent effect of producing synchronized peak positive pulses. The center crossing points were pretty close to what I expected.
The half way points between the peaks, i.e. the point halfway between the tab moving toward the sensor and the tab moving away from the sensor, are about were I thought they would be. As we know the crank peaks are 45 degrees apart that puts the nearest crank zero crossing at about 12 degrees before the cam's and as we know the crank sensor pickup is set up to 10 degrees BTDC that would put the Cam pulse pretty close to TDC.
Now all I have to do is generate something that looks like that and feed it to the ECU.
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ridgeracer
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posted July 21, 2007 09:40 AM
Edited By: ridgeracer on 21 Jul 2007 10:41
I just feed an AC sine wave into both the crank sensor and cam sensor pins and got essentially the same thing...
This image is the AC sine input to the sensor circuit superimposed on the TTL signal that ends up at the CPU timer capture pin. When sensor+ is greater than sensor - the TTL signal goes high then falls to 0 when the sensor input signal crosses 0, the moment the tab is centered on the sensor. (orange dot on graph in previous post)
This jives with what I saw in the software. It sets the capture mode to falling edge on the CPU pin meaning it triggers when the sensor tab is centered. So it looks to me like I can feed the ECU simple square waves from some Pulse Width Modulator outputs I have. I'll have them both idle low then have cam go high, crank go hi, crank go low, followed 10 degrees later by cam low.
Rgeorge- I think the manual test procedure misled you. In the schematic both Yellow sensor wires go to pins identified as sensor + while the browns go to sensor - Of course I guess it could be argued that the label identifies which lead of the sensor is connected and not what kind of signal the ECU expects. Previously however I traced out the cam and crank sensor circuits so I could figure out which signal went to which pin of the CPU to help me with the software disassembly.
This is the crank but both circuits were similar. The diodes on the negative pins hold them near ground. In both circuits the CPU is pulsed when sensor + is more positive than sensor -
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rgeorge
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posted July 21, 2007 11:08 AM
Edited By: rgeorge on 21 Jul 2007 14:15
Whats with the approx 1.5v dc offset on the cam sensor?
edit: Ignore the DC offset on the cam sensor.
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ridgeracer
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posted July 21, 2007 12:24 PM
Thats a good question. This schematic is for a B1/B2. Which model did you get your data off of?
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rgeorge
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posted July 21, 2007 03:11 PM
Edited By: rgeorge on 21 Jul 2007 16:16
Data is from my B2
I think my DAQ had some channel float happening on the log above. This afternoon I used a DMM to check the cam sensor with the engine running. I There was no DC offset across the cam sensor or from either wire to chassis ground.
The cam sensor data from above should still be good but it is shifted.
I apologize for causing the confusion.
I did another acquisition of just the cam sensor.
This time the yellow wire was positive.
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VincentHill
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posted July 21, 2007 06:41 PM
Any "Normal" person under that Language?SOunds like Geek to me You guys are waay beyond real!
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tuusinii
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posted July 23, 2007 02:59 AM
One thing to note when doing the emulator. The Cam sensor is in different position in different years. At least the A an B model have the cam sensor pulsing in different phase to crank sensor. And if they're not right the ECU will not fire the engine. You probably knew this but just to make sure if You run in to problems with the emulator and different ECUs...
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ridgeracer
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posted July 23, 2007 05:34 AM
Actually I wasn't aware of that. Thanks for the heads up. The way I wrote the software to generate signals the 15th crank pulse starts a delay the end of which triggers the rising edge of the cam pulse. Using Rob's data I set the cam pulse width to twice that of a crank pulse. By changing the first delay value I can 'slide' the falling edge to occur anytime before, during, or after the 16th crank pulse.
The little module I'm using has an up,down,left,right momentary switch array. I'm using up/down to change the RPM. I'll just set up left/right to change the lead/lag of the cam pulse.
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