98 Corolla Rough Idle

Hi There I have a 98 Toyota Corolla VE. Recently the check light came on and I was given the P0441 and P0446 codes. The 441 has been present for years because I have a leaky gas cap so thats not really relevant but worth mentioning. The 446 code came on about a week ago and was accompanied by a very rough idle in drive while stopped which became worse and is now rough in park and when taking off. The roughness goes away after getting going at speed. The idle is super rough and stumbles every few seconds. After doing some research and reading I have narrowed the issue down to the engine VSV, the purge valve VSV, the purge valve itself, the canister, or cracked tubing. Not sure where to go for there though and any help would be much appreciated as I would rather do the work myself than having a shop test everything and costing me a fortune!

You may have enough problems by now that you are over your head. I would find a good independent mechanic who can do proper diagnostic work. Then make up a budget to properly fix this car. Don’t go to the dealer or an automotive chain.

My sister had a 1998 Corolla which never acted up and was the best car she ever owned.

From here we certainly cannot pinpoint what your problems are and provide a solution.

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That’s not what I find on the internet. This is;

P0441 Code - Toyota. The P0441 OBD-II code is relatively rare (at least for Toyotas). It indicates an Evaporative Emission Control System Incorrect Purge Flow. The EVAP system manages gasoline vapor evaporation from the gas tank and fuel systems.

So, in other words, not just a gas cap.

And a P0446 is;

P0446 Code - Toyota. The P0446 OBD-II code often triggers with other related EVAP codes (like P0441), and the specific combination of codes can give your mechanic a better idea of where the actual problem lies. Specifically, P0446 indicates an Evaporative Emission Control (EVAP) system vent control circuit malfunction.

You might start by watching this;

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Same car, same codes.If you need to pass an emission test,fix it. If not, learn to live with it.These codes do not affect the performance of this car…mine has been like this forever.

I “second” Docnick’s recommendation.

It sounds like the condition causing the codes has already developed into operating problems. If the purge code was/is being caused by problems with the charcoal canister, it can affect the ability of the fuel tank to breath, causing strain on the pump due to a vacuum developing. That can manifest itself as rough operation and even a failed pump. Normally that’d show itself more prominently at speed, but that symptom may start with more time.

Put simply, the fuel tank breaths in and out through the charcoal canister. The “purge” system allows the engine to draw out the gas fumes accumulated in the activated charcoal. Problems in the canister that trigger a purge code can end up choking off the tank.

The P0441 fault, Evaporative Emission Control System Incorrect Purge Flow is usually caused by an evaporative emissions system leak, I see this frequently, don’t go looking for unusual problems. During the evap. monitor system test, purge vacuum is applied to the system, if no change from the pressure sensor is detected the computer views this as a purge system malfunction.

I had a 2017 Lexus LX570 today with a P0441 fault. $100,000 SUV falling apart? No, loose fuel cap.

Well except for rough idle and rough running.