Engine not running efficiently?

ROSS09

MEMBER
2009 TOYOTA COROLLA
1.8L
4 CYL
2WD
AUTOMATIC
23,200 MILES

Did an engine swap with a 2018 engine, Mechanic told me it was same engine as my 2009. It's 1.8L, but since then it's been steadily declining in performance. It used to get 37 to 35 MPG and now it sits at 24 MPH and lags on the low end. Got plugs for it about 1 year ago and Coils also don't have long either about 3 years old.

Car has 223,000 miles.
Used engine has about 75,000 miles.

5 Replies

JACOBANDNICKOLAS

MECHANIC
108,269 POSTS

Hi,

A decrease in fuel economy can be for various reasons. Simple things such as tire pressure, a dirty air filter, fuel quality, and so on can all cause it to happen.

By chance, is the check engine light staying on while the engine is running? Also, have you noticed a loss of power or anything different? You mentioned a decrease in performance and I'm not sure if you are referring to the MPG or drivability.

Let me know.

Joe

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Sunday, September 10th, 2023 AT 8:38 PM

ROSS09

MEMBER
3 POSTS

Hey there Joe, thank you for answering my question.

The check engine is not on, and I have noticed a loss of power which I'm sure is why I've been losing MPGs. It feels as if something is restricting the engine from running the way it should. At low RPM it feels like it take a while to get up to higher rpm. Once it gets past 4,000 or 5,000 it starts to run better.

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Monday, September 11th, 2023 AT 5:01 AM

JACOBANDNICKOLAS

MECHANIC
108,269 POSTS

Hi,

Often times a power loss is caused by a partially plugged catalytic converter. Have you noticed any odd odors or sounds (rattling) from the exhaust? Also, have you noticed any dark smoke from the exhaust?

Let me know that. Also, by chance, do you have or have access to a live data scanner? If you do, with the engine running and at operating temperature, let me know what the short-term fuel trims are.

Also, take a look through this link and let me know if anything mirrors what you are experiencing:

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

Let me know.

Joe

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Monday, September 11th, 2023 AT 7:35 PM

ROSS09

MEMBER
3 POSTS

Hey Joe,

I don't have access to real time data scanner and there isn't any rattling, but it does smell slightly like gas at the tail pipe. At the moment running a cat cleaner and does seem to get better. How well do those cleaners work? Would you know?

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Monday, September 11th, 2023 AT 9:37 PM

JACOBANDNICKOLAS

MECHANIC
108,269 POSTS

Hi,

I'm embarrassed to say this, but I never used the cleaner, so I can't give you a good answer. The idea that there is a rich fuel mixture from the exhaust may indicate a fuel pressure regulator issue, an injector issue, or even a partially clogged air filter. Heck, even the coolant temperature sensor could be indicating the wrong temperature causing the engine to run too rich.

If you could get your hands on a live data scanner, the short-term fuel trims will indicate if there is a possible issue with the items I mentioned. Let me know if that is a possibility. Also, let me know if the cleaner continues to help.

Take care and stay in touch.

Joe