| remery |
| Ever since I put new tires on the MDX after Xmas I have seen my average mileage drop from 17-18 mpg to 15-16 mpg. I checked the odometer reading with gallons on the fill up and they came out exactly to what the trip computer said so that's not an issue. I find it hard to believe that the Bridgestone tires would make that much of a difference since I keep them properly inflated. The only other thing that I have noticed is the transmission seems to shift into 5th at a higher speed than it used to. Other than that I have no good idea as to the cause for the mileage deterioration. I am due for an oil change in the next 1000 miles but I check the level and it's fine also. Anyone experience similar problems around 36K miles? |
|
|
| frostyra |
| Is the tire size the same as the originals, particularly the outside diameter? |
|
|
| darkhelmet |
| I just put on the my rims and summer tires back on the MDX last weekend and the mileage dropped 2mpg as well. I knew that would happen when I put the 255's on instead of the 235's but if gas hits the levels this summer that everyone is predicting then the stock tires will go back on. |
|
|
| remery |
quote:
Originally posted by frostyra
Is the tire size the same as the originals, particularly the outside diameter?
Yes, that was the first thing I checked when I started to notice the drop and they are identical in size to the old Michelins. |
|
|
| srpbep |
remery,
I find it an honor to reply to one of your posts!! When I was a newbie, read many of your posts which were most helpful.
Your question is one I have "asked before" (most recently on our V6 Accord). Anyway, there is all kinds of "stuff":
** Driving habits.
** Brand of gas! Others swear that this is so (boggles my mind).
** Ambient air temperature. Something about cold air is denser (don't ask me to explain).
** Gas formulation - here in CA we have "winter gas" and "summer gas" (NOT kidding). "Stuff" is blended with the gas to reduce polutants (and reduce mileage). Allows the gas suppliers to mess with our minds and our pocketbooks. During the 2X/year changeover there is always a "shortage" and the gas prices skyrocket. Wife paid $2,75/gal for mid-grade last week!
** Something not quite right in the "engine control" logic. This can be anything from smog stuff to some obtuse temp sensor (e.g. engine fed mixture too rich because temp registered too low, etc), something affecting engine timing (e.g. knock sensor that finds a knock now where it didn't before).
** Resetting the "engine memory" (power failure). I understand that the engine "learns to idle properly" etc. to help it adjust to "normal aging" and still run correctly. If the memory was cleared, it may have "learned differently" and will take a while (have not a clue how long) to get back to where it was.
I am sure that I have been given more reasons, those are just the variables that I can think of at the moment. |
|
|
| remery |
quote:
Originally posted by srpbep
remery,
...** Something not quite right in the "engine control" logic. This can be anything from smog stuff to some obtuse temp sensor (e.g. engine fed mixture too rich because temp registered too low, etc), something affecting engine timing (e.g. knock sensor that finds a knock now where it didn't before).
** Resetting the "engine memory" (power failure). I understand that the engine "learns to idle properly" etc. to help it adjust to "normal aging" and still run correctly. If the memory was cleared, it may have "learned differently" and will take a while (have not a clue how long) to get back to where it was...
These two seem to be the most likely culprits from your post. We have winter blending of gasoline here also with more butane to increase the Reid vapor pressure so cars start when it's cold. Unfortunately, until this winter I did not notice any difference so I doubt this is the problem but I will have the dealer check the ones above.
Thanks on behalf of the Tootsie Roll!!
:D |
|
|
| MGTD |
Using the seat heaters a lot? It can suck up gas just like the AC, especially if run on high with both seats.
Chris |
|
|
| ghost |
Hi Remery, I was pretty fond of the tire size theory, but you seem to have ruled that one one. Here's a couple others:
* Those jackrabbit starts from whenever you pull up to a Lexus RX300
* Diluted oxygen concentration from driving around in that Chicago smog
* Excessive weight of animals in car - I remember old Bullwinkle weighed more than my wife and kids combined!
In other words, beats me! Good luck tho... :) |
|
|
| ELP_JC |
Well, I hope mine doesn't get any worse. Just came back from a long trip, and average mileage was 15.9. All 4 of us weigh 400 lbs, with normal luggage on the back area. Tire pressure at the max 35 lbs. Speeds of 90/100 on open stretches. Temps in the high 70s, with A/C on.
Mileage drops like a rock above certain speeds, probably 65 of so. In a long stretch at 60/70, I got over 20 mpg. I don't watch the mileage, but at high speeds mileage is just like my ex-Navigator 4x4 :mad: .
Anyway, my guess is you probably increased your average speed, or changed some other aspect of your driving, rather than tires by themselves. By the way, I also get 15+ on city driving with no freeway. I wish I could have opted for a 2x4 version: more power to the ground, better mileage, and less maintenance and noise.
Better start investing in oil company stocks :2:
Take care. |
|
|
| hsj |
Got 19 mpg on 500 miles trip...200 out which on way back was nonstop at cruise of 70-75. Never hit 80+ during the whole trip. During city drive, I'm still getting14-15 ..
Come summer, we'll feel the pinch.. |
|
|
| dham |
...How does using the seat heaters drive mileage down? Does that really tax the engine like running the AC? This is the second vehicle I've had with heated seats and I never noticed any difference in MPG in winter.
Thanks... |
|
|
| wmquan |
There's been a lot of bad EGR valve reports here. Occasionally someone mentions that a drop in mileage coincides with it. However, in almost all cases people report the "Check Engine" light along with the vTM-4 problem light coming on sometimes.
Worth asking the dealership to check it, just in case. Seems to be one of the most common issues now. Mine went bad at about 42k. |
|
|
| frostyra |
quote:
Originally posted by ELP_JC
I wish I could have opted for a 2x4 version: more power to the ground, better mileage, and less maintenance and noise.
More power to the ground? How so?
BTW, IIRC from my Army days, it's 4x2, not 2x4. The VTM-4 system IS a 2WD system for probably 90% of the time -- the rear wheels are coasting except for: 1) acceleration; 2) wheel slippage detected or anticipated; or 3) VTM-4 Lock ON. |
|
|
| ghost |
quote:
Originally posted by dham
...How does using the seat heaters drive mileage down? Does that really tax the engine like running the AC? This is the second vehicle I've had with heated seats and I never noticed any difference in MPG in winter.
Thanks...
dham, there was quite a discussion on this a while back - do a search on Seat Heater and Alternator. If I recall, the theory was that the increased electrical demand caused the alternator to kick in more frequently, resulting in diversion of engine power and a loss of mileage. |
|
|
| dham |
| ...thanks...will do. |
|
|
| vicpai |
quote:
Originally posted by remery
Ever since I put new tires on the MDX after Xmas I have seen my average mileage drop from 17-18 mpg to 15-16 mpg. I checked the odometer reading with gallons on the fill up and they came out exactly to what the trip computer said so that's not an issue. I find it hard to believe that the Bridgestone tires would make that much of a difference since I keep them properly inflated. The only other thing that I have noticed is the transmission seems to shift into 5th at a higher speed than it used to. Other than that I have no good idea as to the cause for the mileage deterioration. I am due for an oil change in the next 1000 miles but I check the level and it's fine also. Anyone experience similar problems around 36K miles?
......answer to your question, but in my 24,000 miles of driving the MDX (and obsessively studying fuel consumption on virtually every tank of gas), there are a few things I've found, that affect gas mileage much more than in other vehicles:
Keeping the A/C turned off saves a whopping 1.5 to 2 mpg!! :eek: .....didn't think it would make that much of a difference, but I guess because of the ultra-high capacity compressor (19,000 btu) it must put quite a heavy load on the V6.
I keep my tires inflated a bit higher than the recommended pressure (at 35 to 36psi) and it improves mileage a bit (around 1 mpg or so) as well. Rides a bit harsher, but it's an acceptable tradeoff for me. Handling does improve, though
In your case, it seems to me that the Bridgestone tires might have a much higher rolling resistance than the Cross Terrains (especially at the 32psi pressure).
BTW, did the Cross Terrains last only 36K miles?? :eek:
Aren't they supposed to go 60k to 80K miles or something like that?? :confused: |
|
|
| vicpai |
quote:
Originally posted by MGTD
Using the seat heaters a lot? It can suck up gas just like the AC, especially if run on high with both seats.
Chris
Thanks for that tip! I've been using the heated seats at the slightest pretext. Now I"m gonna have to watch that habit, especially with gas prices the way they are here. :rolleyes: I never in my wildest dreams could've imagined an electric device could affect gas mileage. |
|
|
| dham |
quote:
Thanks for that tip! I've been using the heated seats at the slightest pretext. Now I"m gonna have to watch that habit
When I went to the old thread about seat heaters and gas consumption per Ghost's suggestion (a 2001 thread), I found that it ended without any conclusive proof that it did or didn't impact mileage. So while you might want to be a little more judicious as to when you use the "butt warmers", you probably don't need to be overly concerned about using them either. :cool: |
|
|
| wmquan |
quote:
Originally posted by vicpai
... BTW, did the Cross Terrains last only 36K miles?? :eek:
Aren't they supposed to go 60k to 80K miles or something like that?? :confused:
People on this system are reporting Cross Terrain mileage from the thirties to the forties and fifties, in general.
The Cross Terrains that come with the MDX have less tread than the ones you buy as replacements. :3: So the original tires won't last as long as their successors. |
|
|
| srpbep |
| The Cross Terrains that came on our 02 had 11/32s of tread which is pretty standard from my experience. Has something changed? |
|
|
| srpbep |
I just checked the Michelin web site. They list two Cross Terrains with the appropriate size:
Tire-1: P235/65R17 103T -- This is listed as having 11/32s of tread.
Tire-2: 235/65R17 105S -- This is listed as having 11/32s of tread.
The only diffs that I can see are:
(1) Tire-1 is T rated, while Tire-2 is "only" S rated. I don't really see that as an issue but I am not a "tire guy".
(2) Tire-2 is not a "P235", only a "235". I have no idea what, if any, difference that makes. |
|
|
| DaleB |
quote:
Originally posted by srpbep
I just checked the Michelin web site. They list two Cross Terrains with the appropriate size:
Tire-1: P235/65R17 103T -- This is listed as having 11/32s of tread.
Tire-2: 235/65R17 105S -- This is listed as having 11/32s of tread.
The only diffs that I can see are:
(1) Tire-1 is T rated, while Tire-2 is "only" S rated. I don't really see that as an issue but I am not a "tire guy".
(2) Tire-2 is not a "P235", only a "235". I have no idea what, if any, difference that makes.
I don't think you want to get less than an T rated tire. Not all the dealers sell the same Cross Terrains. That's why sometimes prices seem to vary more than they should.
You want to go for the max treadwear number also. The stock ones are 'T' rated. (as above) and have a 420 treadwear number. I don't think you can go better in this size. |
|
|
| srpbep |
DaleB,
Some specs from the Michelin site:
................................ 103T / 105S
................................--------- / ---------
Rim Width ...............6.5-8.5 / 6.5-8.5
Sect width on 6.5 ... 9.0 / 9.0
Overall diameter ..... 28.9 / 28.9
Tread depth ........... 11/32 / 11/32
Revs/Mile @ 45mph.. 726 / 726
Max load ................ 1,754 / 1,804
Max speed ............. 118 / 112
Treadwear Rating .. 420 / 700
Max speed: I believe that I interpreted the info on the web page correctly. The "T" rated tire does have a higher rating (118 vs. 112).
Treadwear Rating: I believe that I interpreted the rating correctly. For some reason "all OE sizes" are rated at 420. The 103T tire is listed as "Acura OEM". The 105S tire would seem to have a rating of of 700!
Soooooo DaleB, can you please elaborate on the choice of T vs S, etc. |
|
|
| GDTRFB |
quote:
Originally posted by wmquan
The Cross Terrains that come with the MDX have less tread than the ones you buy as replacements. :3: So the original tires won't last as long as their successors.
Why? Are the after market Cross Terrain tires marked or rated any different than the original MDX ones? Is this a fact, or just an observation based on experience? Anyone ever talk to Michelin about this? Thanks. |
|
|
| MesaBeige |
My original Michelins are still going strong at 46K. Probably have another 10-15 K left in them.
MB- |
|
|
| remery |
As I have said in several other posts it's not the tread wear but the sidewall breakdown that caused the premature demise of my Michelins. As far as mileage goes, my guess is the Bridgestones have more rolling resistance which may account for a portion of the dropped in mileage but not all of it. I'll try inflating the tires a little more to 35 psi to see what if any difference it makes but I am still suspicious that something else contributing to the problem.
PS Ghost,
I have signficantly downsized in the total pooch mass department which now measures a feathery 87 lbs of canines (2). Add 4 cats to that and I still come up with less than one Bullwinkle so not likely the cause. ;) |
|
|
| remery |
quote:
Originally posted by srpbep
remery,
...** Resetting the "engine memory" (power failure). I understand that the engine "learns to idle properly" etc. to help it adjust to "normal aging" and still run correctly. If the memory was cleared, it may have "learned differently" and will take a while (have not a clue how long) to get back to where it was...
I am pleased to report my last two tank fulls were 17 mpg or more so I think its bout with dimensia appears to be over. Its mysterious appearance and disappearance makes me suspect it was either the above or some other engine control pertibation associated with middle age.:8: |
|
|
| Oh_My_Baby |
| I agreed with Ghost. Turning up Seat Heater will draw out quite a bit of power from from battery. To compensate the loss, alternator will be activated. Luckily, we won't need it on summer. Otherwise, image both alternator and compressor run all at the same time and all of us would see 10 MPG enough to compete with Hummer for the worst gas guzzler title. J/K :2: |
|
|
| remery |
| I am sure that ghost, living in the vast and barren Northern Tundra uses his bun warmers a lot more than we folks in more temperate climates. Also, since the glacier does recede until May up there in Duluth, he doesn't get the best traction working the ole VTM a lot harder. This also contributes to his winter season mileage erosion. ;) ;) |
|
|
| MDteX |
| When I hit the 1000 mile mark my next tank seemed to increase 1-2 mpg. But then I let my wife drive it and it decreased. Leadfoot!!! :mad: |
|
|
| ghost |
I don't know about mileage erosion, but I've finally decided to enter the new tires market, having put 65,500 miles on my original Cross-Terrains!
Must be driving around in all this soft snow that leads to tire longevity... |
|
|
|
