Wanted: DME for '99 Boxster

Have a check engine light and occasional misfiring thaty mechanic and dealer both think may be caused by a faulty DME. Please contact me if you have one you're willing to sell.

Thanks!
Jay

More likely the alarm or something else. What are the codes?

I've got 7 codes right now. Since the problem began I've had up to 16 at once. I've replaced the O2 sensors per my mechanic's recommendation but still have short circuit codes for all of them. I have a cylinder 5 misfire code, but have seen codes for all 6 cylinders in the past. (I haven't replaced any coils because of this fact, although the presence of only one misfire code makes me want to replace the coil on 5.)

P0132 Oxygen Sensor Ahead of Catalytic Converter (Cylinders 1 - 3) - Short Circuit to B+
P0152 Oxygen Sensor Ahead of Catalytic Converter (Cylinders 4 - 6) - Short Circuit to B+
P0138 Oxygen Sensor After Catalytic Converter (Cylinders 1 - 3) - Short Circuit to B+
P0158 Oxygen Sensor After Catalytic Converter (Cylinders 4 - 61 - Short Circuit to B+
P1128 Oxygen Sensing Adaptation Area 2 (Cylinders 1 - 3) - Rich Threshold
P1124 Oxygen Sensing Adaptation Area 1 (Cylinders 1 - 3) - Rich Threshold
P0305 Misfire, Cylinder 5, Damaging to Catalytic Converter

My mechanic and the dealer supposedly checked the wiring for shorts/breaks independently. I've had the CEL on for a year now and haven't been able to get my car inspected as a result... boy would I love to solve this problem!

(Incidentally, we met way back at the Bentley Publishers tech get together in Cambridge. Hope life is still well for you!)

Thanks, Stefan.

The last three aren't surprising, given that you have no signals to help you control the air/fuel mix. Only hope your cats haven't been damaged as a result.

So why would all 4 signals be saying the same fault..and a short at that? The codes say one of 3 things...DME, sensor or harness. You have checked the wiring (or 2 mechanics say they have), and replaced the sensors. But there is a specific test for the DME that involves testing the output stage. It is #3 in the diagnostic flow chart just after the O2 sensor test and the wiring test. Has that been done?

Good luck.

I certainly hope my cats are okay, too! I know when those codes are thrown because the CEL flashes. Fortunately it's not very often. So hopefully it's okay.

As for the output stage test, I'm not sure if it was completed. Is it something using the PIWIS and therefore dealer only? Or is it something that my mechanic could have performed as well?

j

btw, would you happen to have the flowchart for this issue?



Edited 1 time(s). Last edit at 12/10/2010 11:09AM by Jayusa123. (view changes)

So, I'm back at it once again. Hoping to FINALLY get this sorted out. I would really prefer to know more about the true cause of the problem before I through more money at it in the form of a new (well, used) DME.

I took the car for a drive and logged information with an OBD II scan tool. I'm hoping someone can help me understand the situation a little better. Before I left for the drive I idled at operating temperature. All four O2 sensors were flat lining at 1.115v and I couldn't seem to make them budge with revving. (makes sense considering the short circuit codes--which I still have.) I took the car around the neighborhood with a max. speed of 33mph. After returning, I reviewed the data, and I was surprised to actually see some activity on one of the O2 sensors (1/1). The other 3 O2 sensors flat lined at what I assume is a maximum value (?) of 1.115v.

Below is a snapshot of the ranges for the drive. Do any look out of sorts? Unfortunately I can't export the values to charts on the computer, I can only access them on the tool, but if you would like to know what all the sensors were reading at a particular point in time, I can provide that info.

Thanks, all!

Jay

Speed: 0 - 33 MPH

Tach: 780 - 4500RPM

O2 1/1: .3v - 1.115v
O2 1/2: 1.115v (flat line)
O2 2/1: 1.115v (flat line)
O2 2/2: 1.115v (flat line)

MAF: .5 - 7.5 LB/M



Edited 1 time(s). Last edit at 03/30/2011 08:16PM by Jayusa123. (view changes)