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| New Info. Sorry guys i made a silly mistake with my scope. Basicly my pictures of the cam sensor are wrong and are inverted in my pictures! Please look at http://www.s2forum.com/forum/attachment.php?attachmentid=27419&d=1277585384 |
| New Info. Sorry guys i made a silly mistake with my scope. Basicly my pictures of the cam sensor are wrong and are inverted in my pictures! Please look at http://www.s2forum.com/forum/attachment.php?attachmentid=27419&d=1277585384 |
| I dont think you need to regester to see these pictures. |
| I'm sure you need to register to see these pictures. (if one has cookies already set in the browser that might cause confusion). |
| Right, i had the scope input on the cam sensor connected incorrectly in my first pictures. Instead of ground i was connected to vcc 5 volt, hence the output looking like it was inverted. Here is the new picture. Both the crank pin and cam are on the same scale eg 1 volt/div. So the cam output drops from about 4.8v to 0.3v. The crank pin is AC and is about 6 volt peak to peak. As rpms rise this voltage increases slightly. |
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Right, i had the scope input on the cam sensor connected incorrectly in my first pictures. Instead of ground i was connected to vcc 5 volt, hence the output looking like it was inverted. Here is the new picture. Both the crank pin and cam are on the same scale eg 1 volt/div.
* the cam output drops from about 4.8v to 0.3v. ** that is perfect. The atmega128 (there is clamping for higher voltage, but processor sees almost same voltage in this range as the input) specifies certainly low and high for these voltages. (below 0.7V and higher than 3V are good) * The crank pin is AC and is about 6 volt peak to peak. As RPM rises this voltage increases slightly. ** the amplitude should not be a big problem. See GenBoard/VerThree/Schematic The LM1815 circuit is designed to work in a wide range of amplitude. Too low signal amplitude would be a problem when cranking in very cold winter mornings. ** however, in problematic cases a very weak DC bias could help. I assume you have appr 1k VR sensor x 1k pulldown resistor = 500 Ohm effective pulldown to GND. ** 42k (or slightly stronger, eg 27k) pulldown to -8V would be appr -8000*500/42500=-94mV DC bias, that could get the signal away from the 0V (at 0V it is easier for noise to get injected). Pullup to +5V can be tried, but not as effective as toward negative, as it somewhat defeats the "LM1815 minimum arming voltage threshold". |
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The voltage messured on a stock aby is 30 volt! Mine is only 6. It is true that with 30V signal the signal to noise ratio is better. But it is not the 6 volt itself that is a showstopper, but the relatively large noise compared to the signal.
* either the signal can be made higher or the noise suppression can be tuned with DC pulldown to negative -90 .. -300mV or pullup to positive +90..+200mV * accurately measure the crank pin to sensor distance. This distance should influence the output from the sensor. I will put blu-tac on the sensor and spin the crank and measure whats left. |
| *So what is the minimum voltage vems needs to operate correctly on this input? Has anyone got a circuit diagram of vems on this input? I dont want to have to reverse engineer vems if there is a input spec someplace? |
| I get this trigger fault whenever cold and also at 2200 rpm almost exactly. My wife is calling the car "the frog" as it bounces violently during this trigger fault. Its actually shook something loose on the exhaust as it rattles on the ass of the car now. |
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The voltage messured on a stock aby is 30 volt! Mine is only 6. My 6 volts looks the issue. I need to acurately measure the crank pin to sensor distance. This distance should influence the output from the sensor. I will put blu-tac on the sensor and spin the crank and measure whats left.
I get this trigger fault whenever cold and also at 2200 rpm almost exactly. My wife is calling the car "the frog" as it bounces vioently during this trigger fault. Its actually shook something loose on the exhaust as it rattles on the ass of the car now. |
| The new InputTrigger/UltimateMeasurement secondary trigger log (which needs upgrade to experimental/1.1.76 or 1.1.78 firmware, and new VemsTune) captured during frogging would show if the offending crankhome-VR pulse is before or after the correct pulse. Than we could make some filtering attempt in 1.1.79 to filter it in software (it's not easy, because even if the offending pulse is later, it might be sensed first during initial sync in some cases). |
| Conclusion: |
| Inverted measurement, false conclusion: |
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We'll investigate how we can tell in advance if an engine has this type of HALL sensor or the "mostly-5V".
* It's of less importance normally, but critically important for the 7A flywheel because of the notches. * Thank you for the cooperation and pointing this out. Without the scopeshots this would have been much harder ! |
| The cam sensor is stock AAN unit. I tried replaceing it with ABY but there was NO diference to performance. |
| The cam sensor is stock AAN unit. I tried replaceing it with ABY but there was NO difference to performance. |
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But what kind of HALL sensor is that ?
* Factory or some aftermarket sensor ? * Is the HALL sensor in the distributer or at the front of the head at the sprockets ? (Its a sensor at front of heat at cam pully. Stock audi AAN) * What is the exact engine code the HALL sensor and the 1 window wheel came off ? * does the 1-window wheel have a small window, or a giant window (mostly empty, and metal for a few % only ?) (Mostly metal with small gap. Again stock AAN) |
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The HALL sensor is at front of heat at cam pully. (Stock audi AAN). The 1-window wheel is mostly metal with small gap (stock AAN) |