I have been struggling with poor gas mileage since I replaced my head gastket. I have tried everything I can think of but no luck. Can anyone think of anything I might have missed.

I have tried:

New plugs, wires and distributor cap
Checked mechanical and electrical timing
new O2 sensor

I don't smell any gas leak outside the car, is it possible I might have a bad injector?

Any other ideas would be great!
Thanks

 

When you set the spark timing, did you put the ECU into test mode with the jumper?

Take the spark plugs out and examine them. If one is different then something is wrong with that cylinder.

 

Yes I used the jumper in the test plug. Then I set the distributer according to the red mark i think, can't remember right now.

I will check my plugs again just to confirm they are all good.

Thanks for the reply.

 

What's the mileage (city/hwy)? What year and model Civic? Is the CEL ON?

-Check for an exhaust leak around or upstream of the primary O2 sensor.

-A cold running engine can cause the engine to run rich. Check for a stuck-open thermostat or a faulty coolant temperature sensor.

-Check whether the PCV valve is stuck closed or the breather hose or PCV hose is clogged.

-Check that your valve clearances are set to spec.

 

Hi RonJ

I have a 93' DX 1.5

I am getting about 400-420 km out of a tank which is mix of city and Hwy driving back and forth to work.

I have also recently replaced the Thermostat and coolant tmeperature senors. My valve clearances were check when I had the head machined.

However I have not checked the PVC system or for o2 upstream leaks. I will persue those areas.

thanks for your insite.

 

The only accurate way to calculate gas mileage is, when refilling the tank, divide the number of miles/km traveled by the number of gallons/liters pumped. When you do this, what is your actual mileage?

Is the CEL ON?

 

The CEL is not on and I am getting about 11.5 km/l on average.

 

11.5 km/l converts to about 27.1 miles/gallon, which is not bad, though there is possibly room for some improvement. Mk's and my previous suggestions may help.

Here are other relevant questions:

What was mileage prior to the head work?

Mostly city or highway driving?

Do you have a manual or automatic transmission?

How would you characterize your driving style (grandma or acceleration fiend)?

Are any of the brakes dragging and are the tires inflated to 35 psi?

Is the engine idle running at spec?