OK, the easiest way to explain my issue is through a timeline:

8/2003 - Bought the Accord new, and no problems up until now

NOTE: I consistently averaged 26.5mpg according to the trip computer on the NAVI with my normal driving habits.

7/6/2006 - At 51,245 miles, I decided to change out all 4 Michelin MXV4s with Toyo Proxes TPT. Alignment and balancing was also obviously done.

7/13/2006 - After a full tank of gas on the new tires, I noticed I was now averaging 21.5mpg with the same exact driving habits. The tripometer on the dash and trip computer mileage are still consistent with eachother (+/- .2 miles).

7/14/2006 - Checked pressure, and it was correct by the Honda book.

7/15/2006 - Noticed a strange vibration (nothing too drastic) in the floor and seats at around 28-32 mph.

7/18/2006 - Realized it wasn't necessarily 28-32mph, but rather 3,000rpm regardless of speed.

7/19/2006 - Took it to Honda, and they said it was the tires...after a test drive.

7/21/2006 - Took it to my tire place, they re-checked balance, pressure, and alignment...all good.

Any ideas or past experiences would be greatly appreciated. I'm not really sure if the mpg issue and vibration are linked, or if they're completely separate issues. If they're separate, it's pretty odd this all occurred so close to changing the tires.

 

Hey, I got my 03 the same time you got yours, except mine is now 48k miles.

Anywyay, does the vibration increase as you increase the rpm or does it smooth out at higher rpm (>3000)? It sounds like it rpm related, which means that the tires aren't the problem.

When did you do your last service? Check out all the stuff they did to it, and make sure they didn't damage anything else while doing the service or reconnect everything after they assemble the parts. I had a problem with my speedometer once after a timing belt service with another car. The dealer technician forgot to hook up the speedometer cable after everything was done. Obviously, they didn't do a test drive, because they would've noticed, but they indicated on the service sheet that they did test drive the vehicle.

Check out all vacuum hoses to make sure they're hooked up properly and not being bumped loose while servicing the engine. If possible, snap several pictures of your engine and post them here. We may be able to see something you miss. Good luck.

 

You may have a tire or tires that are out of round. As far as the mileage drop the new tires may have more rolling resistance than the Michs.

 

Tuan: It definitely smooths out at an rpm higher than 3,000. It does however get worse as increase rpm from 2,000 to 3,000.

RTexasF: I checked roll resistance on the Toyos, and they're virtually no different than the Michelin MXV4s.

I scheduled another appointment with Honda for Tuesday, so we'll see what happens. Anyone out there has any other ideas before then, I'd love to hear them.

 

Quick update, and this in completely beyond me how this happened.

Just got a call from the Honda shop and apparently I have a bad axle. They can't tell the cause from the outside, and they can't even tell if it's the right or left so they're ordering both. If someone can tell me how in the world that would have happened at 52,000 miles, I would really appreciate it. If someone could also tell me the best way to get this repaired for free (or a steep discount) considering the following, I would greatly appreciate that as well:

1. I haven't hit anything.
2. This Accord is used primarly as a family car around a suburban area with very little adverse road conditions.
3. IT ONLY HAS 52,000 MILES!

Preliminary estimate is $476 for the part alone.

 

Maybe the axle was made on a monday or friday....

 

this is the same damn problem I have, I own a 2005 accord EX with 24,000 miles i got it when it was 8,000. anyways, after I put some 18' wheels with a 225-40-18 tires i started noticing a little shaking on the floor and seats, however i thought that was cause of the size of the rims, Nevertheless, I replace the stock rims with practically new tires, and I had the same shaking, first I thought well maybe be balance, I balanced all tires and the problem persisted; then I switched rims in case one was damaged, andthe shakingkept going. I have a friend that owns a shop and he revised all mounts and he didn't find anything wrong with them, later on we found a discrepency on the axle the ones that goes into the transmission passg side,well I took my car to a shop where they were supposed to rebuilt the thing, the guys said that the axle housing was damaged due to one of the car's mounts and they just had to replace the housing. well the car ran great for several days but the shake appeared again. I took the car with my friend again and he revised the mounts again and he didn't find anything wrong with them, and I believed him, my car has 24.000 miles!!!!well the best guess now is that the axle bar is lighty curved and that's why I get shakes when I reach 55mph,I haven't find a good price on the axle since is about 200dlls at the dealer and nobody locally have the part. so my advise is,,, lift your car put some stands on the sides and then make someoneaccelerate till youfeel or seethe vibration and check under and see what you see, if you see vibration on the axle then replace it.

 

And that is why you stick with the OEM Michelins.