Hello everyone?
I have a 2005 Accord 4-cyl automatic with 49,300 miles on it. Over past year, I've noticed a noticeable decline in acceleration and gas mileage. As far as the acceleration goes, it's good when you drive it in the mornings and drive the 1 mile or 2 after the car has been parked all night. When I step on the gas the car seems like it’s going to drown and very slowly picks up. :-(
I have been doing regular oil changes with Mobile 1 full syntactic since the day I purchase it brand new, The tires are new and filled with nitrogen, the transmission fluid was changed to the new synthetic transmission fluid from Honda, brake fluid change, new air and cabin filters, new hawk brake pads and brembo rotors. I recently Sea foamed the car but didn’t help. No engine lights are on. I took it to the mechanic and he said everything is fine. But it was in the AM and he drove it around the corner. (

No engine lights are on, the mechanic check the computer and said no codes are being generated. I had the car for 8 years and even my wife has noticed the lack of acceleration.


I ordered NKG spark plugs from Amazon which I am going to replaced next week but according the maintenance schedule it is not due for a tune up until 100,000 miles.
Any clues?
Thanks for your help in advance

 

Check Engine Light On or not?

If on, go to Autozone or other parts house, ask to read codes. Write them down, Pnnnn.

good luck

 

No engine lights are on, the mechanic check the computer and said no codes are being generated.

 

I'm thinking this could be yet another "silent" upstream O2 sensor failure.

 

I agree w/ Shipo. No codes, poor performance hot, OK cold implicates O2 sensor.

good luck

 

And to be clear, check/test the "upstream" O2. The car has two, upstream is before the cat on the exhaust manifold.....downstream is after the cat.

 

Thanks, I will ask the mechanic to check the sensors and report back. i really appreciate the assistance.

 

There really is no way to check or test for a lazy O2 sensor; the only way to see if it is the root of the problem is to replace it.

 

you most certainly can check the O2 sensor. labscope, scantool, HDS...

 

True, if the O2 sensor is fully gone, but I've run across too many that A) caused bad fuel economy and B) test good; once replaced the fuel economy returns to normal.