2000 S80 T6 - P0141 and glowing hot drivers side cat

Post by **Oly_850** » 26 Oct 2013, 20:42

Just rescued this S80 T6, had a blown headgasket.

Got it running, idles fine, no leaks, keeps cool, etc. However when driven a short distance the CEL comes on with P0756, P0300 and P0141, and the drivers side cat is glowing red.

Idles great (before being driven) for about 15 minutes but then rough at ~600 rpm

Codes:

- p0756 is trans solenoid, next project
- p0300 is random misfire
- p0141 is supposed to be rear O2 sensor passenger side ( I think ).

Thoughts on the super hot cat and the bad idle?

Notes:

- Dropped exhaust and checked both ends of both cats, no clogs, no gunk, just tan / white honeycomb on both ends.
- did top end rebuild, valves looked fine, no cracks, has compression
- set VVT correctly
- new timing belt
- new serpentine
- new oil, new trans fluid and filter
- no turbo howl
- no smoke @ idle

Post by **JDS60R** » 26 Oct 2013, 20:52

Start with the misfire as the unburnt fuel will glow the cat. It can take as little as 10 minutes to destry the cat. The ignition and the oxygen sensors are possible culprits. Any oxy sensor over 100K miles in use or plugs over 30K should be replaced. If you don't know then start fresh with new parts.

Post by **Oly_850** » 26 Oct 2013, 21:12

Thanks for your reply, I did put in new plugs and replace one coil pack because it was dead. Maybe a stuck / clogged fuel injector dumping gas in one cylinder? Thanks in advance.

Post by **Oly_850** » 27 Oct 2013, 18:41

Replaced drivers side o2 sensor, fixed a leaking turbo drain seal, but behavior is the same. Loping idle when warm and glowing red cat when driven a short distance. Lots of white smoke and fuel smell, but no over pressure in the coolant bottle, and no water in the oil.

Codes - p0050, p0141, p0300

Next is a warm compression check in guess.

Post by **boosted5cyl** » 29 Oct 2013, 14:12

I know you said you looked, but I would still suspect the car. Pull the front O2 sensor, let it idle for a while and see if the idle stabilizes.

matt5112 · Post by **matt5112** » 11 Nov 2013, 13:29

You could swap injectors from the passenger bank to the drivers bank and see if the glowing cat follows. I know that'd potentially ruin both cats, but one is likely partially damaged already.

Same applies with the ignition coils. Since one has already failed on you, it's not that much of a stretch for another to be causing this issue.

Through swapping them around, you could narrow it down to one. But if one of either set (injectors or coils) is defective, you might consider replacing all six.

Post by **jimmy57** » 11 Nov 2013, 13:40

Is it possible the front oxygen sensor leads are swapped side to side?

Post by **Oly_850** » 29 Nov 2013, 00:22

Further update, thanks for the replies! Cylinders 4&5 had low compression, head was warped .014 and block surface was out of spec at .007 of warp. Machined the head, honed the block surface and now I'm putting it all back together.

Post by **boosted5cyl** » 29 Nov 2013, 11:40

How low was the compression on those two cylinders? Was the motor overheated at some point. The heads will nearly all pull off warped to some degree. Was a leakdown done to find the specific source of the issue?

I hope it fixes the issue, but from the symptoms you presented I'm not optimistic.

Post by **Oly_850** » 01 Dec 2013, 10:32

Compression fixed and even across all cylinders from 135 - 145 lbs, #4 & #5 were low but now have good compression. Took two weekends of honing the block sealing surface with 220 then 400 grit taped to a sheet of glass and hosed down w/ WD 40 got the warp down to less than .004 in all directions. Head was warped .014 in the middle, so the machine shop surfaced it .023 (yes that's beyond spec) to get it flat, took pity on me and only charged me $50. Cam journals won't ever be totally true but there's no binding or evil noises. New headgasket, new bolts,and it runs! Now I'm off to work on the ignition.