CMNTMXR57

This is a 1996 Monte Carlo Z34. My mother has been having a problem with it so I scanned it tonight.

DTC's
P0300 Random Multiple Misfire
P0131 Slow O2 response B1S1
P0410 Secondary A.I.R. injection failure

Pending DTC's
P0131 Slow O2 Response B1S1
P0410 Secondary A.I.R. injection failure

These are the same DTC's as I got this summer. So I traced it to the B1S1 O2 sensor which was causing P0410, therefore causing the random multiple misfire. I replaced the B1S1 O2 sensor and all was fine until today when the same codes came back up. I cleared the codes and went and drove it for about 45 minutes.

Another issue she was having (and I later experienced it myself while driving) is when coming to a stop, the car just flat out dies. In the process of dieing if you watch the tach, it bounces up and down from 500 - 2000rpm and then just flatlines and dies. It'll fire right back up and all is fine until the next stop. This happens about a half hour into driving. So I get home, hook back up to A-tap, and I get P0410 Secondary A.I.R. injection failure.

Can this really cause the car to die coming up to stoplights? Is this the cause of the slow O2 sensor readings?

One of the things I noticed in the freeze frame data was something I noticed last summer too, the barometric pressure reading is 70+ inches of Hg! Later under normal scanning, it shows 29.2 inches of Hg which is right in line with the Barometric pressure at DuPage airport (60185) at 29.99 inches. Could this odd barometric reading in the MAF be the potential source of the problem?

I'm wondering if the MAF may be causing the surging RPM just before it dies.

NX†C

has the car undergone any work done to its catalytics? i would assume under the conditions and examples given that the B1S1 and perhaps the B2S1 would need replacement. these being the before cat sensors are key in determining whether the car once attains temp( after 15-30 mins) would opt to go into closed loop to have proper A/F and mileage. it sounds as if it stays in open loop and if you are having issues with misfire it could be to a point of where coming to a stop it pulls so much timing that it dies.

<small>[ January 31, 2003, 09:22 AM: Message edited by: X']['C WS6 ]</small>

CMNTMXR57

No, no Catalytic work has been done.

I forgot to mention, this car doesn't have 2 banks of O2 sensors. It only has one, those being B1S1 and B1S2.

B1S1 is in the firewall after both exhaust banks meet and the B1S2 is post cat obviously.

Thought has occured that perhaps the cat is clogged. For the longest time she went around driving the car on misfire(s) (which are prone to the "X" motor because of it's plug wire design) therefore it was running excessively rich. But I don't want to go this route until I go through the troubleshooting steps for P0410. Unfortunately I have to wait for a Tech 2 cause it requires some commanding of the A.I.R. pump.

eallanboggs

iTrader: (1)

When cat gets clogged the EXCESS back pressure can force oil back down into the crankcase and below the oil sending unit. Then you might get a LOW OIL PRESSURE lite because of it. I know of a case where a dealership changed out the oil pump in this situation and before the customer got home the LOW OIL PRESSURE lite came back "ON". This sounds like a loose connection at a molex or a wire with worn insulation touching ground because of the INTERMITTENT symptoms.