my 06 civic has 50000 miles on it. it loses power at freeway speeds when going up inclines, will drop from 70 to 60, 55 even with my foot on pedal. the tach. also moves from 3000 to 2000 sometimes. i have used techron, and lucas to clean the injectors, change plugs and air filter. no avail. please advice. it was fine when new
How has the maintenance been kept up?
Do you have a Check Engine Light?
Have you checked for stored fault codes?
The engine isn’t that old. I’d suspect either the plugs are shot, the fuel and/or air filter are clogged, or the fuel pump is dying. The pump can be tested, the other things changed.
Bad sensors will leave a fault code in the computer, as will other problems like poor ignition, and you should check for these codes.
There is also an outside possibility that the exhaust is plugged. That would be highly unusual on a 4 year old car unless some operating problem caused failure and collapse of the ceramic substrate in the cat converter.
My prime suspect would be the fuel filter. If it has never been changed, it is overdue.
However, if the fuel filter has been partially clogged for a while, it is possible that the fuel pump has been damaged.
Start with a new fuel filter, and if the symptoms have not improved, have your mechanic check the fuel pump’s output while under load.
try changing your air filter
The OP stated that he already changed the air filter.
Do you have a roof rack? When I got my roof bike rack I thought that the car had an engine problem but it turned out to be the extra aerodynamic drag was too much for the tiny 1.6 liter engine.