Sifting through some data I collected while playing with my new
OBD-II stuff, I have found something else which might be relevant. Near the end of my tinkering, I had cleared out the DTC, I had cleared out all the stored data on my laptop from the previous runs of the OBD-2 system, started it all up, and took the car for a drive. Somewhere in the course of this, I also ran the tests on the TEST tab, and the results from these were stored. Looking over these results, I see that two of the tests failed. One was the EGRDHHDIS test, which is consistent with the P0402 code in that it indicates that there was much more pressure or flow than there should have been through the EGR system. The other failed test is the CATRAT2 test, which seems to indicate a problem with the second catalytic converter. I'm very hazy on just how the EGR system works, but it seems conceivable that if the catalytic converters are in any way obstructed, it would increase the back pressure, which might increase the flow through the EGR valve. I'm wondering if there's a possibility that there's some other interaction, in the other direction, where a problem with the EGR system could cause the cat to operate below par.
Anyway, just in case anyone else who has the
OBD-2 software wants to look at this data and tell me what you think it means, I've put it up for downloading at <
http://www.impulse.net/~blaylock/96Mstq.zip>; just unZip it, load it into the software, run it, and look at the TEST tab.
