98 Rolla Check Engine Light leading to CAT replacement?
Greetings all,
I'm having some trouble committing to buying a replacement "bolt on" CAT, as I'm not certain that my O2 sensors are both functional.
Some data: My digital scanner tool shows fluctuating voltages from the O2 sensors(.1v to .9v) at all temperature ranges and driving styles (neighborhood and highway), but I thought that I read in the threads here somewhere that the after O2 sensor should stabilize somewhat at higher temp ranges. I have the cursed 1ZZFE with the bad rings that allow about a half of quart of oil to blow through my exhaust every 350 miles, so the probability of the platinum in the CAT being deteriorated is high. The car still runs well at over 200,000 miles. The CEL (check engine light) illuminates typically about 50 miles after I reset it.
My current CAT is welded onto the exhaust manifold, so cutting it out would be my only option, but most of the replacement CATs I find are upwards of $250.00, O2 sensors about $60.00 each.
Is the bolt on replacement a good idea? Has anyone done this CAT job and actually had it fix the CEL? I've read in the threads that many people have done entire exhaust system replacements only to keep throwing the P0420 code I keep getting...so if the forum expertise knows of any specific thread or has some good advice for me, I'd love to hear it before I start dropping cash into the registers at the auto parts store...
The P0420 will return if you use a magnaflow cat. Happened to me, twice. I'll cut it out and put in a generic universal cat from Autozone or something for inspection. I've also replaced my O2s with Bosch front and rear.
IIRC, Toyota also had a TSB for a faulty emissions computer which generated false CELs. I think I saw it on here once, but can't find it right now. They won't do shit about it now because the car has so many miles, but it's worth noting.
__________________
My Vehicles:
2001 Toyota Corolla LE - EBC Ultimax Rotors, HPS pads, Goodridge stainless lines, K&N drop in filter, Magnaflow cat and Exhaust, KYB GR-2, Tein H-Techs
1990 Nissan 300ZX Twin Turbo - More mods than Lindsay Lohan has freckles
Thanks for the heads up on MagnaFlow, I'm looking at a Walker cat right now, so that definitely puts me in the right direction, I hope. Any reason you specify Bosch O2 sensors? Is there a "don't buy" brand of O2 sensor out there I should stay away from as well?
Has anyone used Evan Fischer replacement catalytic converters? I found a VERY reasonably priced (and hence, my skepticism ) cat at Auto Parts Warehouse, which is one of the companies that advertises on these forums...
pull out your O2 clean it off, then space it off your exhaust. How? Go to your local autoparts store buy 2 spark plug spacers. Drill out one with a 1/2" bit. Then screw the o2 into the drilled out spacer. Next screw that combo together with the other undrilled spacer. Then put back onto exhaust pipe. Should be problem solved. Could also just be a fried sensor but in the long run this could save ur o2 sensor from so much oil blowing through exhaust
The Following User Says Thank You to GreenYoda For This Useful Post:
I'm going to try that next if replacing the donut gasket doesn't alleviate my problems.
__________________
My Vehicles:
2001 Toyota Corolla LE - EBC Ultimax Rotors, HPS pads, Goodridge stainless lines, K&N drop in filter, Magnaflow cat and Exhaust, KYB GR-2, Tein H-Techs
1990 Nissan 300ZX Twin Turbo - More mods than Lindsay Lohan has freckles
Thanks for all the advice everyone...I finally got the rolla up on safety stands today to start really looking at what I was up against. Once I got the heat shield off of the exhaust manifold I could feel a distinct air popping from the donut between the manifold and the down pipe, so I went ahead and replaced that today as a start. In the process I also pulled and inspected both O2 sensors. Since they were both cycling their voltages (according to my diagnostic scanner, anyway), I put them back in place so as not to replace too many components at one time. They both showed evidence of foul air, (carbon and soot, easily brushed off) but all the sensor ports were clear, they almost resembled spark plugs running too lean...
Question: how bad does an exhaust leak prior to the CAT need to be in order to cause a CEL and code to be thrown. The donut I removed was almost completely gone, but I only notice a slight difference on the quietness of the exhaust system. Like I said, I could feel the exhaust air popping on my hand, but I wonder if that's enough to fool the computer...
Any thoughts?
Phlingwinger
Last edited by Phlingwinger; 01-31-2011 at 06:43 PM.
Since they were both cycling their voltages (according to my diagnostic scanner, anyway), I put them back in place so as not to replace too many components at one time.
If they were both cycling voltage while installed, your cat is bad. The rear sensor should be a flatline basically. If they were installed. If they were out of the car, then they're both working correctly.
How hard was that front donut gasket? My bolts are all rusted to hell, so I think I'll need to replace the hardware as well.
__________________
My Vehicles:
2001 Toyota Corolla LE - EBC Ultimax Rotors, HPS pads, Goodridge stainless lines, K&N drop in filter, Magnaflow cat and Exhaust, KYB GR-2, Tein H-Techs
1990 Nissan 300ZX Twin Turbo - More mods than Lindsay Lohan has freckles
BigTDogg, Sure enough, even though I fixed the leak I already have a pending P0420 on my diagnostic scanner, just waiting for the catalyst monitor drive cycle to complete before it throws the code officially...so I agree with you, I'm in the market for a new CAT...
The only advice I can give you on the donut would be to spend a few days spraying Break Free or Sili-Kroil on the spring bolts at the top of the down pipe and on the ring clamp at the back end of the down pipe...it was definitely worth my time as my hardware showed all of the corrosion you can expect from operating a car on the Florida coast for 200K miles. I was able to break torque on every bolt without stripping or snapping any of them. Also, pull the forward O2 sensor from the down pipe (you can get to it pretty easily from the top side of the engine once you remove the exhaust manifold heat shield) before you break torque on the spring bolts, once the torque on the spring bolts is loosened the down pipe flange can tweak over and eat up all the clearance for your socket unless the sensor is out of the way... the whole job took about two hours, not counting the time spent jacking the car onto safety stands...
Good luck with those bolts!
Phlingwinger
Quote:
Originally Posted by BigTDogg (MA)
If they were both cycling voltage while installed, your cat is bad. The rear sensor should be a flatline basically. If they were installed. If they were out of the car, then they're both working correctly.
How hard was that front donut gasket? My bolts are all rusted to hell, so I think I'll need to replace the hardware as well.
The Following User Says Thank You to Phlingwinger For This Useful Post:
Don't get a magnaflow, it's a piece of canine feces.
Quote:
Originally Posted by Phlingwinger
Good luck with those bolts!
LOL, I'm not touching those bolts, but thanks for posting the process incase someone else wants to try it. It's 13°F this week, with 2 feet of snow due by tomorrow night. But I will spray some PB blaster on them for my mechanic, he's a nice guy and I don't want to pay for more hardware either. I'll have him replace that gasket and reset the CEL, then wait to see if it's triggered. If it is, I'm getting a O2 spacer and resetting then going from there. Worst case I cut out the cat and have a generic welded in.
__________________
My Vehicles:
2001 Toyota Corolla LE - EBC Ultimax Rotors, HPS pads, Goodridge stainless lines, K&N drop in filter, Magnaflow cat and Exhaust, KYB GR-2, Tein H-Techs
1990 Nissan 300ZX Twin Turbo - More mods than Lindsay Lohan has freckles
pull out your O2 clean it off, then space it off your exhaust. How? Go to your local autoparts store buy 2 spark plug spacers. Drill out one with a 1/2" bit. Then screw the o2 into the drilled out spacer. Next screw that combo together with the other undrilled spacer. Then put back onto exhaust pipe. Should be problem solved. Could also just be a fried sensor but in the long run this could save ur o2 sensor from so much oil blowing through exhaust
Well, the CEL came back on, so I went to Pep Boys and bought a couple spark plug non foulers, followed Green Yoda's instructions above, and so far no CEL, and my after O2 sensor is rock steady in it's voltage output...holding my breath for the catalyst monitor drive cycle to complete @ 70 miles after the CEL was cleared...but I think this "fool the computer" spacer trick may have worked...thanks Green Yoda and BigTDogg for helping me out!
Phlingwinger
Last edited by Phlingwinger; 02-04-2011 at 07:44 PM.
Well, the CEL came back on, so I went to Pep Boys and bought a couple spark plug non foulers, followed Green Yoda's instructions above, and so far no CEL, and my after O2 sensor is rock steady in it's voltage output...holding my breath for the catalyst monitor drive cycle to complete @ 70 miles after the CEL was cleared...but I think this "fool the computer" spacer trick may have worked...thanks Green Yoda and BigTDogg for helping me out!
Phlingwinger
Please keep us posted if this did work! I reset my ECU this weekend while cleaning battery terminals and the code came right back. I'm due for inspection this month and I'm not psyched about expensive repairs.
What did you ask for at PB, spark plug non-foulers? Are they out on the floor or behind the counter?
__________________
My Vehicles:
2001 Toyota Corolla LE - EBC Ultimax Rotors, HPS pads, Goodridge stainless lines, K&N drop in filter, Magnaflow cat and Exhaust, KYB GR-2, Tein H-Techs
1990 Nissan 300ZX Twin Turbo - More mods than Lindsay Lohan has freckles
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) cat at Auto Parts Warehouse, which is one of the companies that advertises on these forums...
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