So I've had this 96 SSE for about 5 years. Before I got it, it was a 'company car', garage kept and maintained by the dealer. I've put about 80,000 miles on it (it'* at 194k). I normally do all of my own maintenance, but this is the 'newest' car I've ever owned and it has more sensors than all my of other cars combined!
There is some history that may be pertinent - so bear with me. Last summer it started hesitating, jerking (sometimes pretty hard), especially on acceleration or under load (going up hill, etc). I thought it was a coil, since I had already replaced two of the three, but it wasn't quite the same as when the others failed. Replacing the last coil didn't help much - I guess it could still be one of the 'new' coils.
At any rate, it had been (since shortly after I got it) occasionally throwing a code P1406, which until recently I couldn't identify. I purchased PCM Scan and and an interface to check the code and it simply told me 'Unknown Diagnostic Code'. I now know it has to do with the EGR circuit. But it'* only occasional maybe once a week and will clear on it'* own if I let it.
At any rate, one day I went out to leave for work and as soon as I started the car it shut-off, like I had turned the key back. Over and over again it did this. No check engine light, it would start fine, engine would respond to the accelerator, but after 2-3 seconds, just shut-off.
After several days of beating my head against the hood (and the battery charger), it finally threw a code - Mass Air Flow sensor - just my luck, the most expensive one! I replaced it, same thing. PCM Scan is showing 2.11 g/* coming from the mass airflow sensor. So I started checking the wiring and found where the +12v lead to the sensor was was cracked and possibly shorting to the +5v where it was cracked as well - more like dry-rotted. I peeled back the covering on the harness and taped up the bare/broken spots and now I get good readings from the sensor. Car starts, and runs, again. But it is still spitting and choking while driving. MAF will drop to 2.11 on occasion still, so I may have other bad spots in the wiring yet to find.
Now that I know more about the obdii params, I've noticed some interesting things: fuel rail pressure sits at 749.29 psi, eq_rat is 0.005 - all the time. I know what these parameters are - and these numbers are not only wrong, but they should change. Are there any other sensors that I should be paying attention to that may tell me why these two parameters aren't changing the way they should?
Was that too long?
Thanks for any help/advice -