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morganism

Cat Converter Plugged On 1.8L ?

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Just replaced the upstream O2 last summer, now downstream failing.

 

Can't go over 45 uphill, downshift causes bogging.

 

idle exhaust is not very forcefull, but it is a 4 cyl...

 

No whif of oil or gas in radiator.

No trouble filling tank, tho a bit of gas smell when starting.

oil burning is going down a couple oz,s a month, since we started changing it less. No choclate milk there....

Water resivoior not dropping noticebly, even in desert sw.

200k miles, but not a lot of long trips on this vehicle. Big altitude gains/losses as daily driver. 3500 to 5000 ft a day.

Dealer charged us a 1k last year trying to fix. No fix. i replaced O2 , ran pretty good till now...

 

2001 le, 1.8l

 

I understand there is a computer/software bug in these cars, and there is a big downhill coast/engine brake happening in afternoon after starting, which would increase rich fuel loading, but am suspecting Cat now...

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Just checked records.

 

Dealership changed O2, AFM, plugs, wires, injectors, coilpacks, All in the last year, problem not fixed.

 

nearly 4k, and still havnt found the prob. Ouch.

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Possible it is a clogged cat - backpressure test with a probe or if you notice a considerable amount of blowby, then that could be the case.

 

But it takes a LOT to clog a catalytic converter. Exhaust leaks can also cause the ECM to misread O2 values, causing the engine to run too lean or too rich - which will affect power.

 

Not completely understanding what the dealership changed or why: O2 sensor (upstream), plugs, injectors, coilpacks - I can see as possible culprits, hopefully they gave you the old parts back. Wires? What wires - spark plug wires? I hope not, your car doesn't have plug wires. AFM? Not on a Corolla - maybe a BWM or similar. Unless they meant the MAF sensor - those can be cleaned, don't have to replace them.

 

I'm surprised they didn't check the VVT-i system - as that would cause a lot of headaches if it wasn't running as it should. If the valve overlap is not right with the VVT-i, could get stumbling, low power, bogging at high speeds, etc.

 

Transaxle issues are another possibility - especially if the car works OK, just doesn't want to get up past a certain speed. This would also point to that funny downhill engine braking you are seeing, should be doing that unless the fluids are too cold. Could be a bad shift solenoid or transaxle.

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