Did I Just Fry My Catalytic Converter?

[Gumart1]

Like a dummy I recently hosed off my engine and, though careful to cover components, may have gotten water in the spark plug wells or in the cracked distributor cap. My engine has run rough from that time on.

I intented to do a complete tune-up AFTER I replaced my alternator. For the alternator replacement I removed the radiator for easier access. I re-installed everything and when I started the car it idled even rougher than before.

I took it for a drive hoping that I would burn off whatever was causing the problem. Instead, on the way home, I could barely accelerate and heard a knocking noise from the rear of the car.

When I got home, the passenger side catalytic converter was bright red and smoking! Now, from my research, I am guessing this is a by-product of not getting good ignition from the plugs, due possibly to my hosing off the engine and getting water there. It's just that for days before it ran sort of rough but nothing crazy, and today this mess happened after I replaced the alternator and put the radiator back together. I refilled the fluids correctly and don't see any leaks. I hope I didn't ruin it completely because I know how darn expensive the cats are!

[akewlguy]

Man that stinks..

I cleaned my engine and I was so careful with the water.

I read a topic once where someone stated to leave car running.. So I did and I did not aim the water near the plugs or wires..

Good luck..

[SRK]

The glowing cat is the result of it converting a large quantity of unburned fuel, resulting from the ignition misfire. You should remove all of the spark plug wires and clean them and dry them. Use a bit of silicone di-electric grease on the inside of the boots where they contact the porcelain of the plug. This will help prevent flash-over, and make the boots pull off easier next time. Check the inside of the caps as well.

A constant engine misfire is never good for a converter. Once repaired you will know soon enough if the converter has melted down internally.

[95LS400Bob]

And you might want to pull it off and look through the converter. The stuff inside has been known to form a ball when overheated...and restrict the exhaust system.

[wwest]

I have only had two catalytic converters fail, and they both displayed the symptom you describe. In both cases the honeycomb structure containing the catalyst had failed and chunks of it were downstream blocking the exhaust flow.

Both these occurred at 100k+ miles and I was told that was about the normal life expectancy. 1992 LS400...., my bother's 92 has 123k, a friend 140k. You may have only slightly accelerated an impending failure.

[WhiteSC3005SPD]

Just a thought - my SC300 recently had a problem where it was running fine, and then suddenly started mis-firing, and barely ran at all. I pulled into a gas station, filled the car with gas and then tried to re-start. The car didn't want to start, and then started - but VERY rough. I was able to get the car back home, where it would not start again. I thought the issue was either electrical/electronic system related or gasoline system related. It turned out that the main electrical input wire into the distributor cap was cracked (almost in half!), so the ignition system was not getting any electricity to the spark plugs. Sounds like that might be your problem as well - rough running -- unburned fuel (caused by spark plugs not firing). I'd be curious to see if the distributor wires are OK (check for cracked or loose wires). Might be a quick, cheap fix. Good luck.

[monarch]

I have only had two catalytic converters fail, and they both displayed the symptom you describe. In both cases the honeycomb structure containing the catalyst had failed and chunks of it were downstream blocking the exhaust flow.

Both these occurred at 100k+ miles and I was told that was about the normal life expectancy. 1992 LS400...., my bother's 92 has 123k, a friend 140k. You may have only slightly accelerated an impending failure.

←

Since about the mid-1980's Toyota factory orginal catalytic converters have been capable of lasting 500,000+ miles. Last December when my '92 Toyota pickup had 451,000 miles it passed a California smog test with room to spare.

http://i5.photobucket.com/albums/y189/mastertech/smog92.jpg My '89 Corolla also passed a smog test earlier this year at 239,000 miles as it also has the factory original catalytic converter.

But I agree with you that the average owner may get only 100-200K miles of life from the factory original catalytic converter. I think that's because the average owner has a "lube, oil and filter every X number of miles" mentality about preventive maintenance of a Toyota - they won't take the car in for service of anything else unless the engine runs bad. Result? Elevated rates of gasoline consumption which in turn causes the catalytic converter to run hotter and fail sooner.

[VBdenny]

This is what caught my attention. Your statement was

When I got home, the passenger side catalytic converter was bright red and smoking!

Maybe in 1992 they had two catalytic converters but my 1990 only has one? The pipes break into duals after the cat.

[Gumart1]

VBDenny - Yes you are correct - I just happened to look under the passenger side and see the glow and assumed with the dual exhaust but I was wrong.

Yesterday I followed Lexls' easy tutorial and gained access to the plugs and wires. I haven't seen the plugs yet but I found that my wires were originals from 1992 now with 152k miles on them. The car ran and idled very smoothly before all of this but I decided I will be doing a major tune-up including plugs, wires, caps and rotors, pcv, air filter. Or should I check for resistance with the wires and leave them if they are OK? Who manufactures the wire set for Lexus? Is it Denso like the plugs? I prefer OEM, but does it really matter with the dist.caps and rotors and pcv?

From what I can find the catalytic converter replacement, if necessary, is a fairly straight forward affair that involves removal of a few bolts. I will remove it to have a look as suggested and I'm not too optimistic based on the sounds I heard while driving. Or, is there another way to check restriction to the exhaust other than how well the car runs?

I look forward to getting this baby back on the road very soon. Thanks for all the input and suggestions.

[jbarhorst2]

My dealer suggest running wires no longer than 120,000 miles (2 sets of plugs in my SC300).

I would replace them. They are not that expensive and your car most probably needs them anyway.

Tom

[chubyball]

Look like you are going through with what I had went through. If you need to know more info. Let me know. It's a headache to figure things out to get your wheel running smooth again.

[Gumart1]

Thanks for the support. The problem still exists. I checked all the plugs and they looked fine except for normal wear. The gaps were all good. The wires looked fine and they had plenty of resistance. I also checked the caps and rotors which were a little bit of a PITA to get to, geez I would have done the timing belt again if it already hadn't been done. Both the caps and rotors were dry and no signs of abuse or cracks. I hair dryed the wires and sprayed dialectric spray on the plugs and wires to remove any possible moisture. I ran the engine in the dark and could not see any sparks. All the wiring looks intact.

Is this scenario possible...Before I hosed off the engine, it ran as smooth as glass, but Lexus during an inspection found a code 25 stored and suggested replacing both pre-cat o2 sensors. Is it possible that the misfiring that occured from my water could have made the sensors go completely bad and then take out the catalytic converters at the same time?

Now all I get on startup is a very rough running engine (no codes though), the exhaust stinks (unburned fuel?) and it puffs out the exhaust as if it's clogged (unless it always puffs).

Before my cat glowed the engine was running rough but not this bad. I don't want to replace all my plugs, wires, caps, rotors, and o2 sensors and find out its just the cat or vice versa, or can there be another problem such as a damaged ignition coil or other wiring?

[monarch]

I'd tend to agree with the Lexus dealer about replacing the oxygen sensors and the catalytic converters since they would have been cooked by the exhaust overheating.

However, if it was my car, I'd be somewhat worried that the rough running might be caused, in part, by low compression on one or more cylinders. If that were the case then even new oxygen sensors and cat converters would not completely solve the rough running. So before spending the money on the sensors and converters, I'd check the compression using a $29 gauge from Walmart like this one http://i5.photobucket.com/albums/y189/mastertech/comp.jpg

Although checking the compression is almost as easy as installing a spark plug, the ignition system must first be disabled following the procedure outlined in the factory manual. If you don't understand or follow this procedure, some expensive ignition system components might be damaged and then you'd really be in trouble.

Your engine needs to have high and even compression (around 170-190 lbs on each cylinder to run silky smooth and quiet with good power and gas mileage.

[chubyball]

If your cats still glowing then you have problem, otherwise, you just have a code#25 and the car running fine then reset the computer by pull off EFI#1 or EFI#2. See if the code still come back up if it does then you have problem. I suggest that you keep checking your cats if your car does not drive normal. Usually the cats are bad you can feel the performance of accelerate is bad.

[Gumart1]

Well, thanks for all the input everyone. I found the easy way to take care of the problem...I sold the car yesterday. My '92 had a list of issues a mile long, and did not have a good maintenance history. The car still ran like a champ but I'd rather find another with a good history.

Besides, now I can focus on care and enjoyment of my '98, which I love almost as much as our 3 month old baby daughter. 2 Lexus' were fun but I almost burned myself out and that is not good.

One thing I have learned after looking into parts and learning some DIY on the forum is that parts are not that expensive if you know where to look, and labor is not that difficult on most jobs if you use the shop manuals and tutorials. I definitely have no plans to part with my '98 (with a picture perfect Dealer maintained history) for a long long time.

Thanks again for the input and I hope this thread may help another with this problem.