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Ahsai

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Everything posted by Ahsai

  1. Ahsai
    Thinking more about it, there's one way that can make all the measurements consistent...your blue/red wire is disconnected from the DME harness side (hence you can't find it there) AND it's shorted to ground somewhere so you got 0.5v signal measured before between pins #3 and #4 on the harness side.
  2. Ahsai
    Not really, just quietly smiling when progress is finally made....... :thumbup: Thanks for your clear mind :notworthy: bringing us back on the right track. That's why you're a pro and we're not.
  3. Ahsai
    Well, pin #46 (blue/red) is the sensor ground to all 4 sensors proided by the DME so if it's missing, got to be the smoking gun! I can hear John laughing :) Where did it go though? The Durametric readings seem to make sense also. I still have problems recociliing this latest discovery with the measurement you took in your post #29 where you said you got 0.05v for which I asked you if it was 0.5v and you said yes. "Looking only at Bank 1....I turned on the car ignition (did not engage the starter) and with my volt meter (set at 2.5V) attached to the car side of the connector ( black/white-wire and blue/red) to the O2 sensor cable running from the car...I got 0.05 volt steady. I turned the key off and the voltage disappeared." Anyway, you gotta find that #46 ble/red wire first :)
  4. Ahsai
    Bob, yes that's all you need to do. Durametric connects, runs and retrieve sensor values when key is in the last position before cranking even when engine is not running. It will give you the correct readings of air temp sensor, coolant sensor, etc. It should also report the ~0.45v bias signal the DME sends out to all four o2 sensors as the actual values of voltage of precat and postcat sensors REGARDLESS if the sensors are connected or not. You can repeat the measurements with all 4 sensors disconnected. If Durametric still reads 0.00v with sensors disconnected, you can use your voltmeter to check the actual voltage of the O2 sensor harness signal pin.
  5. Ahsai
    Bob, please look at John's suggested tests carefully. They are testing the signal and signal ground wires (pin #3 and pin #4 on the precat sensors) continuity between the sensor harness connector and the DME. The continuity tests you posted before were the HEATER circuits between the sensor connectors and the DME, which were intact. What about the Durametric reading of the postcat sensors? Do they read 0.00v as well? I did a test for you since my car is waiting for some new cats, I have all my O2 sensors unplugged. I turned the key to the last position before cranking (key ON engine OFF) and used Durametric to read the O2 voltage. Durematric reported 0.46v on all 4 O2 sensors (sensors are not present at all), which is the bias voltage supplied by the DME. Perhaps you can unplug all your sensors and repeat this test to see what Durametric reports? Will give us one more data point.
  6. Ahsai
    An additional thought I had, and the OP may have already checked this so tell me to go sit down if he already has, is to disconnect the battery, unplug the problematic sensor on bank 1 & 2, unplug the harness from the DME, and check for continuity between sensor #2 harness pin #3 and DME harness pin #46; then sensor #1 harness pin#3 to DME harness pin #46 (these should be the sensor grounds). I would likewise test sensor harness pin #4 on bank 1 to DME harness pin #19, and harness pin #4 on bank 2 to DME harness pin 18. If all those circuits are electrically continuous, we may have a bad DME, but if any are not continuous, a harness issue. Hi John, those tests have not been requested yet and I agree those are good tests. So far, the continuity between the DME and precat sensor are only confirmed for the heater circuits to the precat sensors. Regarding sensor signal pin #4 and ground pin #3, Bob measured between pin #3 and pin #4 and got 0.5v on both precat sensors hence it was assumed that the DME's signal reaches the sensor connectors. I agree though it would be good to also perform the tests you proposed to positively confirm it.
  7. Ahsai
    ^Agree
  8. Ahsai
    John, the OP did confirm there's voltage (0.5v) to the precat sensors (harness side) multiple times hence the challenge. I understand that, but as the Durametric system is looking at them from the DME's perspective there still is no voltage being read, so they are effectively dead to the DME. Without the reference signal differential between the pre and post cat sensors, the system literally does not know what to do next. I would start tracing the harness from the sensors towards the DME, looking for damage, pinched wires, etc. The DME has to see voltage at both sensors to control the mixture. I'd also like to see the Durametric reproduce the pre and post cat voltage curves: If the system is not generating the two different voltage curves, the fuel mixture is basically out of the DME's control. Hi John, I also understand and agree with your reasoning. However, the 0.5v the OP measured at the sensor connector (harness side with sensor disconnected) has to come from the DME directly so that also implies the signal wire is intact all the way back the the DME. If that wire was shorted to ground, the OP should have seen 0v at the sensor harness.One sure way to confirm is to back probe the signal wire of the precat sensors directly when the engine is running and all sensors connected like normal.
  9. Ahsai
    John, the OP did confirm there's voltage (0.5v) to the precat sensors (harness side) multiple times hence the challenge. However, Durametric keep reporting 0.00v precat reading on both banks. What gives?
  10. Ahsai
    Are you sure the MAF connection was tight after you cleaned it? The MAF code is new. As John pointed out before, your engine is running lean at idle, TRAs are at the rich limit. Have you checked for air leak after the MAF? Although the O2 codes seem to be gone, the precast O2 still read 0.00v. What are the readings of the postcat sensors? Can you tell us what else was done on the engine other than IMSB? E.g., did you take off the intake runnings? AOS? Basically candidates for air leak. Are plugs and coils in good shape? Did the engine have any symptoms before IMSB?
  11. Ahsai
    That's because 18 is the ground :)
  12. Ahsai
    There are quite a few ground points on the DME for different sensors. See the DME 5.2.2 pinout herehttp://www.renntech.org/forums/topic/28597-porsche-996-dme-pinouts-and-connectors/?p=151444
  13. Ahsai
    My guess is a poti betwen pin 16 and ground since the pressure sensor is metal and it's grounded by screwing into the engine block.
  14. Ahsai
    The signal is generated by the magnetic type sensor that points to the teeth of the flywheel like in the 1st link I posted. I'm sure the waevform is described in the repair manual (you got one?). I found an old post here talking about it. The flywheel has 60 teeth positions but only 58 physical teeth. The two missing ones generate the spikes in the signal. http://www.renntech.org/forums/topic/40945-cam-position-sensor-resistance-readings/?p=217349 Is the reason to simulate the other sensors just to keep the DME happy and not trip the CEL? If so, it would be a fun project...just think about how to fool the O2 readings, MAF, etc.... I can understand you want to reuse the instrument cluster, which makes sense. I can see you reusing the voltage gauge, speedo, odo, tacho, engine temp with proper sensor or sig processing like the tacho.
  15. Ahsai
    Ok, so you are trying to simulate the crank Signal. I would try a sawtooth wave instead with the last 2 teeth at higher voltage. http://www.picoauto.com/waveform/Sensors/Crankshaft/wave107.html Try at your own risks though :)
  16. Ahsai
    I think I understand your issue now after re-reading your post. Looks like you try to measure the signal from the DME side of the connector with the connector (therefore the crank sensor) unplugged. The crank sensor is of the 2-wire magnetic type that generates it's own signal to the DME so no power or signal is supplied by the DME. http://www.underhoodservice.com/Article/95427/tech_feature_understanding_the_differences_challenges_between_crankshaft_position_sensors.aspx
  17. Ahsai
    How did you test the signal? Did you tap into those wires when the engine is running? The pin numbers are correct for both DME5.2.2 and DME7. You used a scope or multimeter?
  18. Ahsai
    Are you sure it's a key fob problem and not a receiver problem? There's a TSB to increase the remote range http://www.renntech.org/forums/index.php?app=downloads&module=display&section=download&do=confirm_download&id=672
  19. Ahsai
    What's puzzling is he performed all the tests under "Check Oxygen sensor" and varified that ~0.5v between pins 3 and 4 on ALL 4 O2 sensors so the DME signal is getting to the sensors. However, I agree that 0.0v reading from Durametric also means signaling wire shorted to ground since the DME outputs 0.45v on that signal wire (pin 18, 19) with respect to the ground pin 46. Basically inconsistent measuements that cannot be reconciled. Perhaps he has an intermittent problem where the fault comes and goes at different times when measurements were taken.
  20. Ahsai
    For an opened container, I like to use a ziplock bag and push out the air to minimize the moisture. I think ideally you could use one of those vacuum sealing machines for food that sucks up the air and seal the bag by melting the seams.
  21. Ahsai
    Ok, this seems to be something new since you're never had problem jump starting the car, right? It does sound like somthing wrong with the starter or cable barring any loose jump start connection. Anyway, I hope you get it resolved at the shop and do let us know what they find.
  22. Ahsai
    +1 on Loren's suggestion. With new precat O2 sensors, even if the heaters are not working, once the sensors are warmed up enough by the exhaust gas, their voltage should start to swing between 0.2 to 0.8 approx once per second at idle. The heaters are just there to warm up the sensors faster and get the car to optimal a/f ratio faster.
  23. Ahsai
    Japanese reliability, enough said :)
  24. Ahsai
    Lol, no worries. Do let us know what you find. Sounds very frustrating.
  25. Ahsai
    But my old Cayenne S did it every day. Even in winter with heating, light etc That's impressive.
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