Hello, I'm trying to track down an issue with my Camry that began happening this week in that it loses power going uphill. If you floor it while it is doing this it will begin bucking a bit. It loses power to the point to where you're barely moving. Letting it sit a bit or getting back to level ground it seems fine.

This of course points to clogged catalytic converters, but I replaced both of them a year and a half ago. Some details on that: I had the P0420 code for 5-ish years before replacing the cats. I had a bad exhaust leak at the mesh pipe so when I replaced that I decided to go ahead and replace both catalytic converters, and I re-used the original sensors. The P0420 code remained after installing the new converters and clearing the codes and I just let it go since it was running fine (I know, probably a bad move) and I figured it may have been a result of buying cheaper catalytic converter replacements.

Fast forward to now. So far I've cleaned the throttle body and MAF sensor and installed new spark plugs and an air filter. Quick test drives show that it is still having the issue. I should add that the back of my Camry has a light layer of soot/oil-like build up, and it appears to be in a pattern beginning at the bottom of the bumper where the exhaust pipe comes out.

Is it possible that I had a faulty oxygen sensor all along that resulted in a richer air-fuel mixture, and my new cats are indeed clogged already after only a year and a half?

The most recent problem codes it generated were P0420, P0441, and P0446. After letting the car sit overnight with the battery unhooked, I hooked it back up today and went for a short ride and hammered on the gas on a small hill and it began bucking and cutting out, it hasn't generated any new codes yet. The next things I have planned are to replace the fuel pump strainer thing, test the TPS with either an ohm meter or through OBDII, and maybe pull the o2 sensors and try giving them a cleaning.

Just looking for some pointers on where else to look. If the new cats are clogged this soon, is it possible to run something through them to clean them out, or would they be completely shot already?

 

Might be fuel pump.

Is the engine burning a LOT of oil?

Is the check engine like on or blinking?

 

We average about a quart per month, sometimes a little more. The check engine light has been on steady for several years, codes were P0420, P0441, and P0446 before I cleared them. It sucks because I came across some things I could check with an OBDII Bluetooth adapter and the Torque Pro app, but since I reset the codes the car needs to be driven about 150 miles to complete its emissions self-test, but the car cannot be driven very far at this point.

So, without any additional codes to look at, it seems like it's going to be a cash fest, throwing money/parts at it until it works. I kind of want to try blowing out the cats with chemicals and a power washer since they're only a year and a half old, but I also don't want to have to put it all back together just to tear it apart again since I don't have a lot of confidence in that working.

Could the spark plug coil packs be bad without throwing a code?

 

Excess oil consumption can poison the converter and sensors.

Aftermarket converters tend not to last as long as the original.

Do an intake vacuum gauge test to determine if the exhaust has is plugged up. The internet has info on how to do this.

The 0441 and 0446 is the EVAP system. Typically these codes don't cause driving issues.

Toyota has a very specific drive pattern for checking each code. If one knows the pattern one can greatly reduce the driving.

See private message.

 

Reviving my old thread here with some new questions. To bring things up to date, my catalytic converters were indeed clogged and falling apart inside. For now I have opted to simply blow the guts out of them since I didn't yet find the source of the issue of the engine running really rich and going through a lot of oil.

And sure enough, the oil issue still remains, and is to the point of going through almost a quart of oil a week. Since working on the car back when I started this thread in July, I cleaned off the back of the car, and a new layer of oil has built up on it since then. You can smell a lot of oil in the exhaust and it visibly smokes a little. Current trouble codes are P0441 and P0446.

I was looking at the charcoal canister and hooked a 9 volt battery up to the purge switch and heard it clicking consistently as I hit the contacts, so that part seems to be ok. I did not pull the entire canister out yet since I wanted to check here first and ask about other things within the engine that could be causing this since I'd like to avoid pulling that canister out if it isn't the issue since it looks like it isn't going to be easy to get out. The car is fairly high in mileage at 270,000, so I'm wondering if it's just time for a rebuild? Other than the thing of burning a ton of oil, the motor runs great!

 

That much oil burn is bound to plug up the converter.

Have you checked the PCV system?

Any white smoke at cold start up?

Are you sure there is not an oil leak from the engine?

Possible issues for P0446Open or short in VSV circuit for vapor pressure sensor

VSV for vapor pressure sensor

Open or short in vapor pressure sensor circuit

Vapor pressure sensor

Open or short in VSV circuit for EVAP

VSV for EVAP

Vacuum hose cracks hole blocked damaged or

Vacuum hose cracks, hole, blocked, damaged or disconnected

Charcoal canister cracked, holed or damaged

Fuel tank over fill check valve cracked or damaged

Inspect the canister for cracks and damaged hoses. Make sure the VSV valve actually works as in the valve opens and closes.

 

There is white smoke. I replaced the radiator back in August and It doesn't appear to have lost any coolant since then, it's still full up to the cap. It had leaked oil for a few years to the tune of about a quart a month (which old timers will say is "normal"), so I replaced the oil pan gasket back when I was working on the cats in July/August since it seemed like the oil may have been coming from there (and after finding out that these engines don't have the replaceable seal like the previous model did). I've been occasionally checking since then and thought that had eliminated the leak though I'd always see one or 2 mystery dots on the ground that indicated there may still be a leak somewhere but I could not pinpoint the source of it, but it seemed way better compared to before I replaced the gasket. I cannot see too well under the front of the car at the moment due to having the back tires up on ramps, but I just checked after it had been sitting on the ramps since yesterday, and there is an oil puddle forming on the floor around the area of the exhaust flex pipe, but it's not coming from the exhaust.

I just shot a quick video of the exhaust smoke and attached it to the post and I'm now realizing that it's a bit worse than I had originally thought. (It's about 55F in my garage today, I don't think it's from the cold!) I also found a few other threads on this forum about the codes I'm getting and it looks like there are several of those valve switches that I'll need to seek out and check along with the lines and will probably have to pull that canister to rule it out, but I have a feeling that the amount of smoke this thing is generating will point to a bigger issue than the EVAP system.

 

If the purge air valve is closed when solenoid off the engine will run normally if the EVAP system is off. The setup is designed to open the purge valve at certain times to draw the fuel vapors out of the charcoal canister.

Check PCV system which if problems can over pressure the engine internals.

If a coolant leak into the engine the smoke would smell sweat and perhaps the engine oil look like a brown milkshake from coolant mixed into it.

Bad valve stems seals tend to have white smoke at cold engine start up from the accumulated oil build up over night.

That much oil can cause the converters to plug up.

What weight of oil are you using? Sometimes a high higher weight oil can reduce consumption.

My guess is the oil control rings return holes my be plugged up and the result is the oil is not being correctly scrapped from the cylinder walls. Or the cylinder walls are glazed over.

The cars computer does not respond to disconnecting the battery to clear codes. This needs to be done via the ODBII system and a code reader. Disconnected the battery will cause the ECU to need to recompute the engine idle speed via the electric throttle and as such there may be idle issues until it does.

 

Is there a particular valve you are referring to, or should I check out all of the several valves that are part of the EVAP system?

Oil seems to be alright and doesn't show signs of water getting into it. I'm aware of using heavier oils in older cars, I usually get 10w30 for it, but my son runs it more than I do and he tends to get 5w30. Probably should always be using at least 10w.

Thank you for all of the advice!