i just had my girlfriends motor rebuilt in her car but now she is getting really bad gas milage why?

Answer 1

Any of a hundred reasons. I would ask that of the people who rebuilt the engine. That, and check the rear tires. If they look like all the tread is burned off, I'd tell her to stop dumping the clutch.

Answer 2

it is very possible that this is normal. before you do any major work, the first thing you do is disconnect the battery. this erases some of the computers short term memory. now that the engine is back up and running, the computer and engine kind of have to relearn a few things. fuel trim is very critical. exactly how much gas do i need to be able to perform at optimum efficiency with out destroying the cat?
i have a small question that some one else already asked, what kind of car ( year make model and engine size) , and what was wrong with the engine before. also how long ago was this done.

Answer 3

By really bad gas mileage, is it that great of a reduction? The new engine is tight and the mileage should improve once it is broken in and the parts loosen up.

But it wouldn't hurt to take it back and have them look at it. It could be they have some stuff way too tight or you aren't getting the right fuel / air ratio.

Answer 4

if the engine is completely rebuilt with new piston rings you got to let them wear in because if you dont the cylinders will leak and thats no good. drive the car for about 1000 miles before you get the engine above about 4500 RPM.

Answer 5

What kind of car? why was the engine rebuilt?

Answer 6

They goofed up something with the carburetor/fuel injection or dropped something into the exhaust pipe that is blocking the exhaust gas from getting out.

Answer 7

Take it back to the rebuilders. They need to tune it or do other mechanical checks. Should be no cost to you as it is their reputation they are protecting.

Answer 8

calibrations.take back to the meck.