Red Hot Cat...now Only Runs To 500 Rpm

[junklexus]

I noticed the drivers side cat turned cherry red on a trip from Spokane to back to my home in Seattle, (400 mi.), I reluctantly limped about another 10 miles home.after discovering it..and it progressively lost more power the last 2 or 3 miles... I was told that it probably cooked the cat converter on that side and took the sensors at the cat (fore and aft), and now they are feeding the wrong data or NO data to the computer. I still don't know if that is the most accurate scenario or is there a more complete one? I already replaced 1 coil and swapped it left and right with no change in the problem. Sounded like a dead coil allowed the right bank to dump raw fuel into the cat. No improvement. It still won't exceed 800 rpm and does not have enough power to move itself ahead on level ground.. It just dies. I bet some one in this forum will have some more specific answers. The sensors look like they run about 50 bucks and the cat replacement is about $140.00. Some help on this one would be great. Thank you.

BTW it is a 92 with 218 K on it.We have owned it for 8 years and other than the usual maint., brakes, battery, tires, oil, etc. it has been a very good car. First brain teaser on this one in 8 yrs.!

[SCHONDO]

I had a similar issue with this. I have a 93 SC400 and did a routine Maint. on it. did oil change, caps and rotors, and cleaned out the throttle body. once it was all back together went for a test drive and it ran fine. stopped at the store and when i started for home it ran like crap. like only half the engine was running. no power even with the gas pedal floored. when i got home it was smoking and the drivers side CAT was red hot. I let it cool and did some research. found that the ignition coils could be bad. upon inspection it was a badly damaged coil wire. i changed the wire sets out and it now runs like new. I was afraid i would have to shell out the $$ for new coils but sometimes the problem is so simple or small.

my advice is to start from the easiest fixes then go from there.