I recently had the timing belt replaced on my 1999 Acura Integra (which incidentally is a great car). Seems like my gas mileage has been down by a couple of miles per gallon ever since.
Is it possible that some normal aspect of replacing it would reduce gas mileage? This was a new shop to me–is it possible they did something to the engine that would reduce the gas mileage?
Not unless it was installed incorrectly. But you should notice that when driving. Lack of acceleration…and/or engine knock.
It’s possible they unplugged something and forgot to plug it back in, or it didn’t make a good connection when they plugged it back in. But I would think you would have noticed some differences in performance.
Take it back and ask them to check the connections they touched.
" Seems like mileage is down a mile or two " Not exactly a scientific assessment. Did you check mileage properly before and after timing belt replacement or just guessing.
No check engine light? Everything is probably hooked up. Does it run as strong as it did before? Yes? The belt was probably installed correctly. OR No!, It might be off a tooth and the gas mileage and performance may be suffering as a result.
Check your mileage carefully. Set your trim odometer to zero when you fill up. Next time you fill up divide the miles on the trip odo by the gallons you put in - result = Miles/gallon, do that 2-3 more times. Is it rerally low for the car you drive? No, not really low? Is it the same as before the timing belt change? What? You didn’t check that before the change!
There is no way to compare before and after, sorry. You are at the mercy of your mechanic’s good will to check his work based on your impression that the mileage might be a little “off” Without some data at least, it is solely based on your “guess.”
I will add to all that good advice that it might have been necessary to disconnect the battery which can cause the computer to erase learned patterns of operation which can cause reduced mileage and uneven idle speeds, etc., until everything is relearned.
That is why I have a preference for a memory tender. Had power steering hoses redone last week, now on my model it seems common for actuators for hvac to screw up and need replacement after a battery disconnect, so I turned off ac, shut fan to off, funny but radiao station buttons were remembered but time was lost.
Now I turn on or off ac at idle and the rpms dip, but come back. Had a battery replaced in my daughters 02 Saturn, do you use a memory minder?
Yes ever since a honda would not start after a new battery install and we were on the hook for $1100 for new brains for the car.
So in essence hopefully your car will relearn and you get your mileage back, but to quantify and figure a reason may be an escapade into the unexplained. Make sure all else is up to date, filters, plugs wires etc., and if you feel really courageous disconnect the battery and start over.
Does it run as strong as it did before? Yes? The belt was probably installed correctly. OR No!, It might be off a tooth and the gas mileage and performance may be suffering as a result.
Based on my limited experience, if the belt were off even 1 tooth the car would be a total dog with horrendous gas mileage. Only an extremely unobservant person could have any doubt.
If the engine has a distributor adjusting the ignition time might result in some improvement. But a camshaft is off a cog the engine will idle poorly and lack response when accelerating.