So I melted a PTU, and overfuelled a cat til it was glowing red. No big deal. Even after replacing the PTU, it's still a bit 'doughy' under load. I've done the obligatory 'hand over the exhaust pipe' trick, and there it fairly even flow. I did notice metallic wafer catalyst in the muffler after a few good revs. Revving under no load was not as responsive, but still revved fairly cleanly, albeit with a bit of a 'lumpy' exhaust note. For a fully occluded cat, there would be close to zero flow thru the driver's side exhaust, and you'd think that the motor would not fire at all on that bank if exhaust gas was not being expelled- and it definately does not feel like that under idle conditions. My exhaust system is not factory, but standard generic 2.5inch: Turbo>dump pipe>cat> X-pipe resonator>pipe>muffler. NB a block at the cat would effectively kill 1/2 the engine, and the 'equal flow' felt at each muffler would be the output of 3 cylinders divided at the x-pipe. I can't get a clean view of the cat without a borescope, and the piping before and after the cat is at least 50cm with bends. Can someone confirm that a fully blocked cat would make it almost impossible to idle? Does anyone have any experience with a partially blocked cat? What did it feel like to drive like that? After some answers, I'm going to look into a power balance test, but don't suspect I'll see anything unexpected.
Try this mate > http://www.roaduserdirect.co.uk/catalytic converter cleaner I ran this through my system and it seems to be running a lot smoother now and revs out higher/evenly...The cats get a white looking blockage in some of the core and reduces flow, so yes it will effect performance. Any good exhaust place should have this stuff for sale, or similar to.
I think it has gotten beyond the repair of a fuel additive. Unless of course it can help unblock a plug of molten metal in the cats. I could remove the exhaust at the dumps, but it would be bloody loud, and too loud to drive to the nearest exhaust shop. That would work out if the cat is blocked by removing pipework upstream of the restriction. It would be fun though, bouncing the limiter with no exhaust :br:
To test a catalytic converter, measure the inlet & outlet temperatures. Another use for an infrared temp gun!
Give it a whack with you hand, if it rattle or clunks or sounds like something is loose inside it's rooted. If you have seen converter material in the tail pipe the cat is rooted. Best way to confirm is simply cat the pipe off at one end and have a look. You COULD remove that section of the exh by unbolting at the flanges and tip the exh on its end, if converter material falls out of the pipe guess what - it's rooted. Going by the information you have given us to date my bet is it's rooted, might as well find a shop that can fit the new one(s) and take it there, watch as they check the old one to confirm then just get them to replace it. Easy as that. You can give it a good whack for free though & I'm pretty sure you will here it rattle due to the core being damaged and falling apart, the broken parts of the core clog up the rest of it and nek minnit your car runs like a three legged dog.
