vectre

When I cold start my 2000 Maxima SE it runs smooth as can be for almost exactly 12 seconds then begins to hesitate and sputter until it dies maybe 10 seconds later. When I restart the car it immediately runs smooth as can be again for almost exactly 12 seconds the same thing happens. There is then a acidic or acetone-like or ether-like smell from the exhaust (not sulfuric smell).

If I play with the rpms just right I can keep it running. And if I can manage to get the rpms up high (2500-3000 or more) just once it will run smooth.

I did have a P0140 code - O2 sensor - for a long time, and I recently replaced the sensor but no improvement.

The problem seems to be getting worse in that before, once the engine got going, it ran fine. (Well it was lacking in high RPM torque, and it had poor acceleration however the engine ran smooth. I couldn't go faster than about 75-80) Now, I can't drive it faster than about 30-40 mph. Just no power faster than that.

Someone mentioned by letting the O2 sensor go for so long that it may have done something to the catalytic converter and that is causing this problem...?

I appreciate your thoughts.

Darkrock

When you get a misfire the ECU will kick over to a richer mix to compensate. Which causes the O2s to report a code. I would pull the MAF and clean it. All the parts places carry something designed for cleaning MAF sensor. Do not use carb cleaner! Clean it up with spray cleaner only and do not touch it like with Q-tips you may scratch it. The low power (less than 3k) and bad fuel mix suggest the MAF sensor. If you get performance improvement but just not 100% look at replacing MAF. Good luck.