1997 Honda Civic Idle control valve/gas mileage

SCRAPPY30

MEMBER
1997 HONDA CIVIC
4 CYL
4WD
AUTOMATIC
132,000 MILES

I just had the following items replaced on my 97 Honda Civic LX:

Head Gasket
Water Pump
Timing Belt
Timing Belt Tensioner

After about 1 month, I am getting a loss of gas mileage and horsepower (from 29 MPG to 24-25 MPG). Also, my car is revving up to about 2000 RPMs at certain times of the day when stopped in traffic or at lights.

I have 2 questions.

1. My car was revving up to about 2000-2500 RPMs before I had the head gasket replaced (the car was overheating but has not since replacing the parts above). The mechanic said that the head gasket replacement should take care of this but it didn't. The car only does this during hot temperatures outside between 11 A.M. And around 7 P.M. When I go to work in the morning, it does not rev up while sitting in stop and go traffic or at a light. It will do it if I run some errands during my lunch break and on the way home from work.

Does this sound like my idle control valve? I figured I could clean it first before replacing but I wanted to know if anyone had experienced similar symptoms.

2. Does anyone know why I would have lost gas mileage and horsepower? Is my timing off? I didn't have this problem before the replacement work was performed. I'm not sure what I need to check first in this case.

1 Reply

F4I_GUY

MECHANIC
3,302 POSTS

If your ignition or mechanical timing is off, then yes you could have lack of horsepower.

And your revving issue is most likely your IACV. I recommend cleaning it with throttle body cleaner first. If that doesn't solve the problem, you will need to replace the valve.