Clogged Cat, Slip Control Warnings, stealership ranting

[Steve85]

I don't know about GM stuff, but when the engine light comes on on a toyota, it almost always also sets the VSC light. Why? For most codes, I don't have a clue. But it does.

My guess would be that throttle (engine power/braking) is used as part of the overall VSC system. When there is problem with the power delivery system, it handicaps the VSC, default is to turn VSC off and warn the driver of impending certain doom.

[ViPER1313]

I got the code pulled today: P0420 Catalyst Efficiency low-bank 1

Probably cause: catalytic converter defective failure possibly due to

Engine misfire or running condition
large vacuum leak
engine oil leakage into exhaust valve guide seals, piston rings

I guess I am going to have to get this fixed via a dealer, I can't find aftermarket parts anywhere. I thought about trying to pull one out of a junkyard, but not sure if thats a good idea or not. I also can't find anything online that says whether or not the whole manifold has to be replaced, or if the cat comes off. Anyone ever seen one that was the kind of design before? on gmpartsdirect.com I found a listing for "Catalytic converter, malibu, 2.4l " for $126 but I can't quite tell if that's the one for me, or what it comes with, since there are no pictures

Problem with catalytic converter efficiency codes is that you don't know whether it is an O2 sensor at fault or the cat itself. The same thing happened with my old Taurus GL - I just installed a rear 02 simulator to make the problem go away because I didn't want to pay for a new y-pipe. I would try and replace both 02 sensors (if one is dead the other one is probably about to die anyways) just because it's cheaper, and if that doesn't fix the problem you are going to have to replace the cat as well. If you just replace the cat and the O2s are messed up, it is probably going to kill the new cat with a quickness.

[Steve85]

Can you swap front and rear O2 sensors and see if the code moves? They used to all be the same, I dunno about now...

EDIT: That, and taking out the pre-cat sensor and revving / driving will usually let you know if the cat is actually clogged. The hole is usually enough to relieve the restriction and provide a noticeable improvement.

[HAULN-SS]

I will give that a try - hadnt thought of just taking the forward sensor out. DIdn't think that'd be enough. I couldnt tell from the printout any distinction about which sensor or whatever, so I guess it doesnt show, at least not on the Autozone tester

[ViPER1313]

Taking the front O2 out will most likely make the car un-drivable - it will have no way to monitor the fuel mixture. The rear O2 only measures the gas for the purpose of emissions monitoring in most cases.

[Steve85]

It should use MAP and MAF and whatever else to determine fuel needs and, instead of applying adjustments according to O2 feedback, it will realize the O2 is not "switching" assume it is faulty, and continue to get reaaaaallll close using the other inputs handicapped only slightly by a loss of feedback.

I have diagnosed several clogged cats by removing the O2 sensor in fron of the cat and suddenly the car goes from choking at 3K rpms to revving freely.

It's been several years so perhaps strategies have changed. I wouldn't think a MFR would want to have a situation where the car becomes undrivable due to a faulty O2 sensor. Best to just set a code and continue to fuel based on the other inputs.

[D_Eclipse9916]

It should use MAP and MAF and whatever else to determine fuel needs and, instead of applying adjustments according to O2 feedback, it will realize the O2 is not "switching" assume it is faulty, and continue to get reaaaaallll close using the other inputs handicapped only slightly by a loss of feedback.

I have diagnosed several clogged cats by removing the O2 sensor in fron of the cat and suddenly the car goes from choking at 3K rpms to revving freely.

It's been several years so perhaps strategies have changed. I wouldn't think a MFR would want to have a situation where the car becomes undrivable due to a faulty O2 sensor. Best to just set a code and continue to fuel based on the other inputs.

It will use pre-based maps within the ECU based on the hertz of airflow and intake air temperature. The o2 was mainly put in cars for emissions purposes, but it does allow us to get as clean an idle as possible. A car does not need to be 14.7:1 to have a nice idle, hence why a lot of dsm people "lean burn" their o2s so that they get better cruising and idle gas mileage. This however produces more "bad emissions". The idle stability of a vehicle more depends on the ECU tables, MAF, IAT, and idle speed switch.

[NTIman]

Toyota seem to have a REALLY high O2 sensor failure rate... My Mom has has 3-4 in her 2003? RAV4.

Theres a recall on Rav4s which could be the problem, its for a recalibrate when setting p0420s. Also, rav 4s have 4 sensors which is retarded on a 4 cylinder. i also consider them to be among the worst overall toyotas built.

I don't know about GM stuff, but when the engine light comes on on a toyota, it almost always also sets the VSC light. Why? For most codes, I don't have a clue. But it does.

My guess would be that throttle (engine power/braking) is used as part of the overall VSC system. When there is problem with the power delivery system, it handicaps the VSC, default is to turn VSC off and warn the driver of impending certain doom.

Still makes no sense to me that a VSC light comes on when an old woman can't tighten her gas cap on her avalon

[Steve85]

Still makes no sense to me that a VSC light comes on when an old woman can't tighten her gas cap on her avalon

:lol:

Hey, do you still crew with any of the racers at Winchester Speedway? My boys are asking to go again, maybe I'll stop by and say hi real quick...

[NTIman]

I haven't been this year, but plan to soon. This weekend I'll be in Richmond, but if you're there sometime other than that, find the white Mustang 1RD and I might be around. Just ask for Jelly (don't ask). I might be there next weekend though, if he's going to race.

[HAULN-SS]

Heh, this just keeps getting better. I took it to Shutzman Chevy in winchester to get it fixed, and ended up driving it home. I got a mailer from them for 10% off any service, which I realized was completely negated because they want 65$ to "diagnose the problem" whether it is a warranty problem or not. I posed the question 'so you mean I have to pay for you to fix it, AND pay for you to tell me what the problem is?" Sounds like a complete ripoff to me, so I told the guy i'd let it grenade before I gave them 65$ for diagnosing the problem, especially on a 500 dollar repair bill.

And in positive news, the guys at the dealership where I bought the car in roanoke are going to get back to me monday, and I think they are going to fix it under warranty, or on the cheap. I got the sales guy involved who I have bought 2 brand new cars from in the last few years, and that seems to be motivating them to work with me.

[Steve85]

It should $65 to diagnose... If you choose not to have repair done, then 65 is it. If you have the repair done, that "hour" gets rolled in. If it's warranty, then no charge even for diagnosis. To begin work on the car you need to agree to pay 65 in case it is not covered under warranty.

Are you saying they were going to charge you the 65 even if they found it was warrant-able? Or were they asking for you to agree to pay 65 minimum in case it was not a warranty issue?

Sounds like the Roanoke dealer is handling it well, sucks you have to go that far. The only reputation worse than than the quality of an american car is the reputation of the dealers.

[HAULN-SS]

this:
"agree to pay 65 in case it is not covered under warranty." being completely separate from the actual repair bill is what pissed me off, mostly since I know they would simply pull the code (~ 5 seconds of work) and then start work on the car. What i was asking for was the diagnosis for "what caused this to happen in the first place" in the event it was not just that the O2 sensor went bad. I dont think it's the sensor that caused the cat to go out, i think that the sensor being bad is also a symptom of whatever the real problem is. There was no time gap between CEL (which the sensor bad would've caused, too) and the loss of power/clogged cat. Just makes me wonder if I've got a valve problem or something else as mentioned in this thread and elsewhere.

In other news, I am in roanoke right now, and drove my 25 year old SS down here, and it's driving like a dream. I have half a mind to sell my malibu, buy another beater and put a motor in it and live happily ever after. I got slightly over 20mpg for the trip, too.

[Steve85]

Yeah, I'm not sure what the problem is. Years of doing this and never had a problem explaining that while the scan tool does only take a few seconds to pull the code, that is only the start. It does nothing more than tell the tech what page of the diagnostic manual to start on. The $65 is to go through that procedure of pulling the code and then diagnosis aka, "what caused this to happen in the first place". All in an effort to fix it right first time. And if not, that repair is refunded and any further diagnosis is my time, my dime. (Unless I can BS you into believing both issues were the cause, momma needs new shoes ya know)

So? What did Roanoke say was the problem-o?

[HAULN-SS]

Oh, i forgot to update the story. Car is parked and I am driving other vehicles in the mean-time, but basically, they got back to me with a "ok, so we can't fix it for free, but we'll discount the labor, and get you the parts at our cost: total of $785"

So I am going to fix it myself. Plan is to take it apart tomorrow, see what all is involved, and try to hunt down the parts via junkyard. I think i found a full manifold in PA for 120$