1997 XK8, #1 cylinder shows oil, possibly lost chrome bore, excess oil shows from pipe on down run and acceleration
Autobox jams in top, is this the C02 sensing blocked Cat? Computer causing Limp motor?
Several engine warning etc, ABS lights

Quick cure, clean out Cats with thinners, Trick Sensors, simple cut and loop wires? will this work?

Long term fix is motor out and new many items, thats another day when retired

 

Hello gardcycl,

Is P0430 the only diagnostic trouble code present? The definition is "Catalyst efficiency below threshold Bank 2." If your car is going into limp mode or restricted performance, you will probably have additional codes stored.

You can do a basic check of the catalytic converter by running the engine to full operating temperature, then using an infrared (non-contact) thermometer to check the exhaust temperature at the inlet end and outlet end of the cat (avoid the heat shields). If the converter is operating properly, the outlet temp should be significantly hotter than the inlet temp, typically around 40 degrees C / 100 degrees F or more higher.

When you say the #1 cylinder shows oil, do you mean around the spark plug, or actually inside the cylinder with the spark plug removed? Oil around the spark plug is an indication that the spark plug tube seal has failed. These seals harden and perish over time. The seals are easily replaced along with the camshaft cover seal.

If you have excessive oil inside cylinder #1, stuck or broken piston rings would be one possibility. If the rings are stuck, it would be worth trying an oil change and adding a couple of bottles of oil detergent in place of two liters of oil. You could also try adding some Marvel Mystery Oil to the cylinder and letting it soak for a few days to help loosen gunk that can cause the rings to stick.

Hopefully others will have some additional ideas.

Cheers,

Don

 

I mentioned this same fault to the service guy at the dealership and he said it was my O2 Sensor. He said it can pop up if you run low octane gas or if it just gets faulty. I cleared the code and will wait to see if it comes back.

 

It's possible a failing O2 sensor can trigger the P0430 B2 Catalyst Efficiency Below Threshold code, but there's no way the service guy at the dealership can know for certain without proper diagnosis. It's easy enough to check the Bank 2 catalytic converter, oxygen sensor signals, fuel trims, etc., instead of guessing.

Cheers,

Don

 

I agree! I had the same code except for bank one on my 2006 STR. This was after I had tried to tackle the infamous lean codes several times and repaired various vacuum leaks around the engine as well as replacing the catalytic converter pipes.
after resolving the lean codes I started seeing this cat efficiency code for bank 1 but only on bank one. Knowing that I had just replaced the catalytic converters I was suspicious that it had nothing to do with the cats but I had to make sure so I took the exhaust pipe off and visually inspected the converter to see if there was any damage to the internal structure and it looked fine. I did notice that the replacement pipes that I used had a small ridge at the exhaust manifold flange at the end of the pipe which might prevent it from sealing at it’s mating surface so I took a file to smooth it out and I reinstalled the pipe but the code still popped up periodically. Then I started messing around with the carburetor cleaner while watching the bank 1 02 sensor outputs and I noticed a little wiggle in the signals when I sprayed the cleaner near the back of the engine but I couldn’t zero in on an exact location. It’s seemed to be coming from Back of the intake manifold or EGR but I couldn’t find specifically where it was. I did move a bunch of The cabling around in that area as well and i could see o2 signal changes. i wiggled the fuel injectors for cylinders 3 and 4 to try to get them to seat better and I noticed the OT signals wiggle very slightly again while I wiggled. I still wasn’t sure if this was a vacuum leak situation or an electrical connector issue or maybe some electrical truss talk in the cabling but after I finished I had great o2 signals and the code has not reappeared so I’m blaming my cat efficiency code on either a connector issue a wire routing issue or my fuel injector O-rings because that’s all I messed with trying to fixing it. Good luck it’s not an easy repair to troubleshoot

 

Not sure if the US / AUS is different but my 97 XK8 does not have downstream O2 sensors so it has no way of knowing if the cat is working or not!