Help with mpg please.

[Turdle]

I know tire brands differ, however from Falken's website

235-75-15 yields 734 revolutions per mile
31-10.50-15 yields 693 revolutions per mile

so 5.3% I was a bit off.

I know at 40mph I am dead on with the portable photo radar trailer nearby, and only off by 2 at 65 mph which is close to 5% give or take. Not a factor for this type of fuel consumption.

 

[dubbio]

5% would be barely anything on 13mpg. id check brakes and wheel bearings, tire pressure, maybe check the trans fluid to see if its burnt indicating possible slippage. check the accessories too, bad bearings up front can drag on the engine, and if you have a lot going on electricaly (amp(s), lights, etc) your alternator has work harder and it passes the buck down the line

 

[Marcusford]

OK I will skip the warm up, I did change my brakes, and the calipers, and I will check to see if my cats are clogged. How about my ignition coils? I don't think they ever been changed with the spark plug wires.

 

[1998Exp]

Coils are not routine maintenance items and should last the lifetime of the vehicle. Never heard of them degrading slowly, and if one fails, you will certainly notice, because two cylinders will be misfiring. If you suspect something unusual, you can have the ignition 'scoped' (waveform and peak voltage checked with an oscilloscope).

... How about my ignition coils? I don't think they ever been changed with the spark plug wires.

 

[Marcusford]

So at this point my options are limited. Anything else guys u might think might be wrong

 

[colintrax]

When you changed the brakes did you grease the caliper pins? And when you retightened the pins it was with the caliper assembled right?

 

[Marcusford]

I only replaced the rear calipers not the front. Should I replace the fronts? It does not seem to me that my brakes are giving me a issue. But I will keep that in mind.