Car Died On Track - Codes PO157, P0300, P0302, P0303

[StantonGTI]

Hi All,

 

Have my 1999 911 at the track today. During the first session, car began misfiring, lost power, and eventually stalled (would have turned it off sooner, but had to get off line).

 

Codes pulled from Durametric are:

 

P0157 - o2 Sensor behind cat converter. Cylinder (4-6)

P0300 - Misfire damaging to cat. converter

P0302 - Cylinder 2 misfire damaging to cat. converter

P0303 - Cylinder 3 misfire damaging to cat. converter

 

Other things that may help:

1. Looks like there is oil coming from the AOS area (wet on the side of the cam adjuster) - the AOS only has 10K miles on it, but I know that does not mean anything

2. Looks like there is some oil towards the rear of the motor of the drivers side, coming from above, but nothing looks wet from the top

3. I did try to start it (probably dumb). It runs for a second, and turns off. It is running rough, but does not sound like there is a bunch of metal floating around

 

What's odd about the codes is that the o2 sensor code appears to be on the opposite side of where the misfiires are happening, which does not make sense unless they are unrelated codes which seem unlikely.

 

There are lots of threads with these same codes, ranging from bad o2 sensor (please, let that be it) to blown engines.

 

Where do I start to diagnose? I plan to pull the filter and drain oil to take a look, once the engine cools, but any further guidance would be great.

[JFP in PA]

I think that the P0157 is where to look.  Normally, this is the code for the O2 sensor behind the main cat on cylinders 4-6 being shorted, the sensor itself failing, or the DME crapping out.   Obviously, the DME dying would stall the engine, but we have also seen this code when the main cat failed and broke up, both killing the sensor and causing an exhaust system blockage, which would also stall the car by backing exhaust gases up into the intake, which can also cause misfires.  I'd start by looking at the cat on that side.

[StantonGTI]

Thanks JFP

 

I pulled the screw on filter to check for any issues. Poured the oil into a cup, dipped a magnet in, and unfortunately it was covered in sand sized metal particles.

 

A little looking and a few larger pieces were found. So it is not looking good. Fortunately, I trailerd it down and it was the last event of the season, and I was not assigned a student this weekend so I got to go home early.

 

Over the next couple of weeks I'll drop the pan to see what I can see, but I imagine the motor will be coming out and will be replaced or potentially rebuilt depending on damage.

 

I checked the durametric for over revs. It showed 214. I'm not 100% sure when that occurred. Or what 214 represents. I had not checked for over revs since I purchased the car in April. I did have on not so great shift during the session, but it was a couple laps before I lost power, so it seems a little unlikely the shift caused damage.