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Ahsai

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Everything posted by Ahsai

  1. Ahsai
    Excellent! I agree with your diagnosis that the current bank 1 postcat sensor is bad (aged) because at cold start, there is no reason why it reacts much slower than the bank 2 postcat. It didn't detect O2 until the pump is off. By the time it's too late so the DME thought bank 1 didn't receive the O2 injection. If the bank 1 SAI ports are blocked, the postcat should read rich a/f (high voltage) instead at cold start but it didn't. You can again switch the postcat sensors and see if the slowness follow the sensor. I think it's worthwhile to get a new bank 1 postcat sensor to further diagnose the issue. Use the bosh online part catalog to find the part # then check Amazon, which has great price for Bosch O2 sensors.
  2. Ahsai
    Sounds good. Just make sure you log at least until the SAI pump stops.
  3. Ahsai
    That's interesting. P0139 is bank 1 postcat sensor. Lets see how the SAI diagnosis go.
  4. Ahsai
    Two words - impact gun :)
  5. Ahsai
    Here's my take. All your O2 sensors are fine because you saw them operating correctly most of the time. If one of them is bad in Bank 1, they should not flat line at the exact same time. So I tend to agree with you that the flat line truly means air leak in Bank 1. Also, the DME never flagged any persistent O2 sensor codes so far. The code P1126 was persistent (btw, P1146 was a typo?) You could swap the precat sensors between the banks to verify the above easily. The air intake manifold clamps in bank 1 are strong suspects. Maybe reinstall the plenums and the clamps? Other sources of air leak include AOS and evap purge valve but I would think those should affect both banks. It won't hurt to cover them as well. You will need a manometer to verify proper engine crankcase vacuum (5" water). You can remove the evp purge valve and use a 9v battery to operate it and see if it's sticky and/or leaking.
  6. Ahsai
    Those look like wideband sensors. Ours are narrow band. Do you see these PIDs instead? PID 01 14 Bank 1 sensor 1 precat PID 01 15 Bank 1 sensor 2 postcat PID 01 18 Bank 2 sensor 1 precat PID 01 19 Bank 2 sensor 2 postcat
  7. Ahsai
    http://theautoprophet.blogspot.com/2014/10/review-lemur-bluedriver.html The second last photo shows O2 bank 1 sensor 1 voltage. O2 sensor voltage is part of the generic OBDII PIDs so I would be really surprised if lemur doesn't support those for Boxsters.
  8. Ahsai
    That is strange. The link I sent was just an example, with the maf sensor was selected. Usually these scanner apps will show you a list of sensors supported for your car for you to select. Have you checked if somethng like "O2 sensor voltage bank 1 sensor 1" is on the list? Even a $15 bluetooth scanner can do that. If you use an Android device, you can get a cheap bluetooth scanner and paired it with the Torque app ($5), which is what I use (on my '03 996). Note that P0420 can be intermittent as your cat becomes marginal so it passes the test sometimes and fails at other times (and CEL tripped). Are you sure you tightened up the sensors good so there's no air leak? A Durametric will be the best for sure but I still suspect the Lemur driver supports reading the sensor voltage.
  9. Ahsai
    Agree you have nothing to lose by swapping the sensors. I still recommend you check the voltage directly though as that tells you directly if your sensors are bad (e.g., flat line, not touching 0.1 and 0.7v) or the cats are bad (postcat voltage following precat voltage). Lemur blue can log sensors http://www.lemurmonitors.com/Sample-BlueDriver-Live-Data-Log.csv To get the best possible resolution, it's best to minimize the number of sensors logged so in this case just the 4 sensors.
  10. Ahsai
    You may also want to check this thread http://www.renntech.org/forums/topic/49140-seeking-expertise-from-all-vacuum-gurus-p0492-that-really-wants-to-stay/#entry272177
  11. Ahsai
    It should be very obvious what the problem is once you observe the sensor voltage at cold start and then at operating temp. Sorry to say but P0420 is quite accurate in our cars (bad cat) and also O2 sensors have their own codes. If it's just the internal element got knocked loose, it can be repaired by welding. If the element is consumed instead, the cat will need to be replaced. Thanks. According to a local Porsche-only mechanic and also a dealer mechanic, 2000 and 2001 models are especially problematic. However, I now have thrown a P0420 code, so checking the O2 sensors is certainly the next step!
  12. Ahsai
    Welcome to Renntech! Indeed you seem to have a strange problem. My SAI (a '03 996) sets pretty much after the first couple of cold starts. When I can't explain your situation, you should be able to see if your SAI is operating correctly by logging the O2 sensors' voltage per this http://www.renntech.org/forums/topic/49140-seeking-expertise-from-all-vacuum-gurus-p0492-that-really-wants-to-stay/#entry272177
  13. Ahsai
    Btw, if you could, please keep us posted what you find after you get this resolved. Will help others down the road.
  14. Ahsai
    One day I'll get one :) I need the rear seats so driving a 996 now. These are all great sports cars! I think once you remove that metal tube (part #7), you can probably try to blow into the port on bank 2 where the tube connects to and feel for blockage. Or you can remove the bank 2 header first and check how the small sai ports look.
  15. Ahsai
    Yup, I agree with your conclusion. Please check this thread for photos. That car had 250I miles though. How many miles your car has? http://986forum.com/forums/general-discussions/49666-p0410-secondary-air-injection-system-cylinders-1-%96-3-a.html
  16. Ahsai
    I assume you meant the postcast O2. No, the now in bank 1 sensor is fluctuating only very little. The scale is blown up so it appears to fluctuate a lot.
  17. Ahsai
    Nice plots and it's good to see the postcat reading stabilizes in 0.6~0.7v, which is good. I don't suspect your O2 sensors as all of them swing between 0.1 and 0.7 and more importantly you don't have any O2 sensor related code. I expect to see the exact same behavior of the yellow boxes in my diagram tomorrow despite the sensor swap (i.e., bank 2 postcat still fluctuates when pump is on). Look forward to seeing what you find tomorrow.
  18. Ahsai
  19. Ahsai
    Excellent plots! A few things I observed: 1) Bank 1 sensors and cat seem to behave normally (no worries about those momentary dips on the postcat reading). 2) Bank 2 seems to be not getting enough air injected as evident by the fluctuating precat O2 reading during the time the pump was ON. That's also what tripped the P0492. I suspect either the SAI valve port/line to bank 2 is restricted. Need to check if Part #7 is plugged http://www.autoatlanta.com/porsche-parts/hardparts.php?dir=986-97-04&section=108-06 3) After the postcat sensor became operational, the bank 2 reading does not look normal. Either the postcat sensor is bad or the cat is marginal. It would be really useful if you can drive the car for 20min or so and then let it idle. You should see the precat sensors swing up and down every second or so and the postcat ones should read around 0.7v more or less steady. If you doubt the sensors, you can always swap them between banks and retest.
  20. Ahsai
    That could be because the cats are not warmed up enough. If you drive the car to warm them up completely, at idle the postcat sensors should be more or less stable at around 0.7v If the postcat reading still keep bouncing and following the precat, then the cat is marginal but may not be at the level to trip the cat codes yet. Anyway, the part that's relevat to your error code is steps 3&4 in the diagram where the sensors read 0 (reading the O2 injected by the SAI pump). Do your sensors track the same way to 0? The DME uses this to detect if the O2 injection is working.
  21. Ahsai
    Have you checked if the vacuum reservoir is holding vacuum? It can have invisible cracks at its bottom. Did you also replace all the vacuum lines? With Durametric, you can log the four O2 sensor voltage reading (pre-cat and post-cat) on both banks and make sure you see something like this during cold start:
  22. Ahsai
    Agree with JFP above. Totally unnecessary, especially you have been bleed it every 2 years. I think every 4yrs is frequent enough.
  23. Ahsai
    Thats good news!
  24. Ahsai
    Any chance that dirt/coolant got into the fuel lines when they were open? You need to at least get the car scanned for error codes to see what tripped the check engine light to diagnose it further. Sounds like misfires. How are the conditions of the coils and spark plugs?
  25. Ahsai
    Consider yourself lucky if that's the only thing they gnawed on :)
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