Rather than throw any more parts at it, I'd take it to a dealership and have them trouble shoot it, then you can decide to either have them fix it or you can with the info.

It could be a lot of things and dealerships have the expensive scanners and usually at least one tech that's the "go to" guy that's well versed on finding what's wrong quickly. I would just make sure there's some sort of agreement in front about how many labor hours to find the problem.

I don't like taking my car to a dealership either but I'd hate to see you keep spending money trying different parts than just to get a diagnosis. You could keep buying sensors and it turns out to be a fuel pump, etc.

 

It's not the T-stat.

 

SLVR, did this problem start IMMEDIATELY after the snow/exhaust blockage event? Or was it several days later that the symptoms started?

 

I didn't think it was the TStat either Tom

Ancdmd, it wasn't immediately after. It was sort of a progressive thing that happen over maybe a week I believe.

 

I'm leaning toward Brad's suggestion to avoid throwing parts at it. Get a full scan dealer diagnosis, then decide how to proceed.

 

UPDATE:

Finally got the car to the shop to see what's going on. Got a scan done but no codes were stored on any areas of the car. Got it up on the lift to check the exhaust. Just as it was mentioned before, ITS THE CATS. Almost no output from the tailpipes when hitting the gas. I can hold my hand on both outlets and it will not burn. Matter of fact, i can hold my hand on the resonator. Warm but not hot. Cant do that up front! Both front cats are burning hot. The left one has a leak at the gasket that i can hear and feel. The right one if banged on, makes rattling noises on the inside and is super hot. Now im stumped as to why i havent gotten any CEL's. Should've i got a 430/420 code by now?

Anyways im glad i've gotten to the bottom of this. Now i must to decide on which cat to get. I've decide to go the RockAuto route again. They have a few different brands. Any suggestions on which one? Link below.

http://www.rockauto.com/en/catalog/l...converter,5808

 

Magnaflow is what I would go with. Check out their website for part numbers and be sure to check if your vehicle needs to be CA, NY, or federal compliant.

 

Yes, I would be very concerned about why the P420/430 codes have not come up by now... As I indicated, it "possible" that your engine is stuck in open loop mode when the outputs of the oxygen sensors (which the ECU determines the cat efficiency by analyzing these outputs) are ignored. As there are no fuel trims to adjust the air to fuel ratio to ideal 14.7 to 1, the engine will run rich for extended periods of time. When your cats run hot after initial cold start condition, the unburned fuel in the hot cats will eventually destroy your cats.

Had your cats damaged due to snow restriction at the exhausts, your engine would have been signaling the cat problem by now provided that o2 sensors are monitored by the ECU.

I would check the stuck open loop operation, and if it is the case, try to find out why. Normally the ECU should spit out the P420/430 codes when the cats are not working as they should (and in some cases, even when the cats are OK but a leak exists somewhere ).

 

I'll try to explain. You didn't get any codes because for now, all the O2 sensors are working as well as the ECU requires. Technically, the ceramic substrate in the catalytic converters have melted, causing a partial blockage and partial exhaust restriction. As you have seen, exhaust gas still escapes just enough to provide feedback to the rear 02 sensors, and the gas that does escape is scrubbed by the catalyst substrate that is still in-tact and functioning.

I have seen this happen before on other cars with no MIL or codes stored but never on an LS: their sensor network is too sophisticated, in my professional opinion, for a naturally-occurring malfunction to cause this degree of damage if all sensors are working as designed and not bypassed, and most importantly, the ECU is functioning as designed. Otherwise there would have been a MIL and codes P0125, P013X and P015X stored in the ECU. If that were the case, it would have taken longer than a week of normal driving to ruin the cats unless you went to extremes, such as letting the car run in an insulated area where the cats could get in excess of 1,000 degrees Fahrenheit (i.e. melting point).

The fact that your car was presumably buried up to the doors in snow (you never clarified if it was or not, only stated it was buried up to the tail pipes), was allowed to warm up while you shoveled it out, stalled while you were shoveling, and had a loss of power while accelerating afterwards that had previously not been an issue led me to believe the exhaust had been overheated to catalyst-melting-point due to having been run too long buried in the snow. I further believe your car stalled because the excessive heat interfered with your 02 sensors, causing them to malfunction, but being considered an intermittent problem by the ECU via the 2 trip detection logic, were able to resume normal operation, or close enough, after you had dug the car out completely, it cooled down, and you restarted it.

I'm curious if you had a chance to test the idling vacuum before you went to further expense of having it diagnosed by a shop? I'm confident if you had, you would have come to the same conclusion and be a diagnostic's fee richer. Live and Learn, I've been there too, trust me. I try to help others avoid pitfalls like this I learned early on, years ago. I'm happy you are able to finally fix your car before major engine damage like burned valves set in, or being ripped off by the dealer.

For what it's worth, I'd consider the EASTERN CATALYTIC 808552 C.A.R.B. Approved replacements as they have a heavier wash coat of metals which meet or exceed OEM specs; the others listed (i.e. Not legal for sale or use in California; Not legal for sale or use in New York for vehicles with CA emissions) do not. Best- and worst-case scenario: you won't be able to register or potentially sell the vehicle in one of those states, or the cats will not last as long as the heavier wash coat would.

 

Again, your insight is appreciated. As to being buried, yes snow was up to the middle of the doors all the way around. i had to shovel my way from the front to the drivers side so that could open the door and start the car. After that, it sat idling while i continued to dig. . To be honest, i believe the cats were over worked due to a 02 sensor circuit that had been damaged previously. This,imo, cause the system to run rich and dumped gas into the exhaust for quite a while until i got it fixed. I used to get an overbearing sulfur smell at when i first started out in the mornings and if under hard acceleration. I had the wires fixed at the dealer along with a new B1S1 sensor. It ran ran great for a while but i guess the toll was taken. Fast forward to recently, by the exhaust being blocked heated the system to the point where the cats couldn't take it any more hence my situation . No i didn't get a chance do a vacuum test. Luckily i didn't have to pay for a diagnostic. My cousin manages a maintenance shop and im good friends with one the best techs. Before we even got the car lifted, we did the tailpipe test which gave us minimum exhaust output. Lifted the car and immediately noticed a leak from the gasket on the drivers side and a burning smell and rattle from the pass.side one. Hot up front but only warm to touch in the back. I also had the Y-pipe/3rd cat replaced, a drivers side exhaust manifold that was cracked, and both mufflers which had holes in them done early last year so these parts are fairly new. After this the whole exhaust will have been replaced save for the pass side exhaust manifold and resonator. Left unchecked, running rich for an extended amount of time will have adverse effects on an exhaust system i tell ya.

That said i will be going with those Easterns units. They look decent, i see good reviews and they are one of RockAuto's favorites it seems. I may as well throw in new 02 sensors while im at it since everything else is new. From there, a thorough check of all the coils and plugs will be on deck.

Stay Tuned.

 

Wow, sorry to hear your silver surfer has needed so much work! For what it's worth, you sound like a good owner who stays up with maintenance and takes care of your vehicle! Personally, my fellow engineering buddies and I think that many pre-2007 cars on the road are having so many exhaust-related problems, including sensors, is due to the excessive alcohol in gas being mandated by our government. There seems to be little to no oversight or independent testing guaranteeing you are getting what you believe you are paying for, either. The 2001 LS430 manual specifically warns against using it except when absolutely necessary, and not for extended periods of time. We have our theories, but when it all comes down to it, parts designed and manufactured before the widespread, mandated imposition of gasohol were not ruggedized to handle its long-term use. And it's only going to get worse for older cars and owners who like them and want to keep them going longer because the Federally-mandated alcohol content just keeps being pushed up and up every year. There are places to get pure gas (pure-gas.org), but some are out-of-the-way stations, and all are much more expensive than their gasohol counterparts, usually to the tune of +$1/gal or more. I'd be really interested to know if the sulfur smell goes away after you upgrade to newer technology cats. Please keep us posted!

 

We knew this all along, didn't we. We just didn't want to come to terms with it.

Hope it's not outrageously expensive. Keep us informed! Good luck.

While your cat might be bad, to lighten the mood, I'm posting a pic of a GOOD cat.

 

LOL. Thanks for throwing some positivism in this dim situation. Yes we did guess right in the beginning On as good note, the cat weren't too expensive. Got both (Easterns) for $300 from RockAuto. $58 for a new 02 sensor and the labor (cousins shop) will set me back $100 so just under $500 for two cats is awesome imo.

All in all, if it wasnt for the awesome knowledge and support system i have here at CL, my bill would otherwise be a lot higher.

 

So, after the cats yesterday i immediately went the shop today to have them installed. Thinking im finally gonna get my power back, i was threw another curve ball. Turns out the two cats i ordered weren't clogged after all. IT WAS THE Y-PIPE CAT that was recently installed not long ago that went bad. The rattling noise i thought was coming from the front right cat was actually coming from the middle one. This cat is fairly new and bad already. Maybe it wasn't tough enough to handle that "snow" incident even though it was new. Nevertheless, i bought two brand new converters due to misdiagnosis and a new part that failed pretty quickly. While the system was unbolted, we blew air in one side of the y-pipe to check for flow thru to the mufflers. Instead of flowing through, the air came back out the other opening almost full blast meaning a restriction. I mean you can really hear the innards rattling around when you bang in it. This is a bummer.

Well i went ahead and installed the new converters along with a new right side/upstream 02 sensor anyway.The left side 02 was recently replaced at the dealer. I figured might as well since they were not expensive and at 185k mi. who knows how much life the old ones had in them. They had a pretty rough life and even though things aren't fully restored, i can feel the engine running smoother and quieter with the new cats installed.

I sent RockAuto an email regarding the warranty for the defective part as soon as i found out. Hopefully this wont take too long to get straighten out so again fellas, stay tuned.

 

I tend to think what happened is your exhaust got clogged from the snow, the heat couldn't escape so it melted your cats and that created the restriction.

I don't think it had anything to do with the replacement cats being defective, OEM ones would have likely done the same thing if that had been clogged up.