Hello,
I have a 1993 Honda Accord, 10th anniversary ed with 142,000 miles. I recently had the timing belt, water pump, etc replaced. I also got new tires, michelin 4xm's or something like that and a new muffler. Since having this work done my miles per gallon have gone from 26.8 mpg to 20 mpg. I suspected the timing belt was off one tooth but the people at the auto shop checked it out and said it was fine. The car runs like a sewing machine with plenty of pep, no strange noises, or missing and sputtering, and no check engine light. Also, the exhaust pipe is clean without any soot build up. I checked the timing and it is right. I have kept the new tires properly inflated. I have looked up the muffler online. It is a Walker 18865 which fits my car but is not necessarily the one recommended by other muffler shops. Walker recommends a 54061. Autozone, Advance auto and O'Reilly suggest a walker flowmaster 40 & 50 series.
The whole point is, where did I lose 7 mpg? Anybody out there have some insight or suggestions?

 

Are you basing this on one or two fillups or looking at a longer history? I'd have a second (different) shop check the timing just to be sure to start with.

 

My mpg before the timing belt repair was 26.8 over several years. Since the repair I am on my 4th tank of fuel. I would normally get about 220 miles on a half a tank and 340 to 360 on a full tank, (when it got to the reserve area). Now I'm getting about 240 a tank full. Same kind of driving, same gas station.
I wonder how much difference the muffler could make? I've checked for recommended replacements and not on a single website was the walker 18865 listed. It is always a flowmaster 40 or 50 or a stainless steel one .
As for the timing belt alignment, I was thinking about doing what you said and take it to another shop. I am also considering checking the timing marks myself. I would have done the belt replacement myself, (I have done honda timing belt replacement on my previous accord), but I didn't have the time to get into it. I haven't checked the manual to see what it would take to just check the timing marks, but I think you are right. It is time to have someone other than the shop that did the work check the marks!

 

Just check it yourself , post pics if you're not sure

 

Yeah, I'm just going to have to break down and do it!