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Discussion Starter #1
After having the 3rd torque converter put in my MDX before hitting 100,000, I decided to try driving in D4 instead of D5. My thinking is that all my other Honda's (including Pilot's) are 4-speed transmissions. I read my X's manual and it too recommends driving in D4 on Hilly Highways. I instantly had improoved shifting performance around town and anything under 65mph. Driving in D5, my MDX always sounds bogged down. Similar to pushing really big gears on a bicycle. When you constantly push big gears on a bike, you prematurely wear out your drivetrain by stretching the chain and curling the teeth on the cogs, all from the added stress. So my theory is that poor shifting performance of the 5th gear overdrive is somehow prematurely wearing out the torque converters. Pilots, which don't have a 5th gear, don't have TC problems. Make sense?

The only benefit to the 5th gear, from what I can see, is better gas mileage. Even at 75mph, I rearly go over 3000rpm in D4

ps. I'm really not a car mechanical expert
 

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ts8169 said:
Pilots, which don't have a 5th gear
News to me. I thought all Pilots had the 5 speed transmission?:confused:
 

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Discussion Starter #3
The 2006 I was in recently only went up to D4 on the shifter column, so I assume that's a 4-speed. I could be dead wrong though. I have no idea with the newer ones.
 

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Discussion Starter #5
I don't know exactly on mileage, but it's not signifigant. 2-3mpg maybe. Haven't noticed. Similar to driving around with a ski rack on the car all the time I'd say. My little computer has displayed 18.3 for the longest time and I mostly drive around town. On highway trips I shift to D5 around 60mph and go from 2500rpm to 1500rpm. No sense in keeping it in D4 for 100 miles of flat highway.

Besides, driving around town, there's no need for overdrive to kick in, therefore there should be no difference in gas mileage. But for some reason there is a HUGE performance difference. I can't understand this.
 

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Pilots do have a 5-speed transmission. In fact, our 2006 pilot does not allow a d-4 shift setting, only the lower gears (D3 and below). This is one of the things I like better about the MDX vs. the Pilot.

Of course, it's entirely possible that the shift points are different.
 

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A2MDXer said:
Pilots do have a 5-speed transmission.
+1
http://en.wikipedia.org/wiki/Honda_Pilot

I don't understand either why you would see a difference in performance unless the shiftpoints are dynamic based on the gear you are driving in (D5 vs D4). I mean if D5 doesn't kick in until 45 mph, why would you see any benefit to driving in D4 below that speed, for example?
 

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Discussion Starter #8
phins2rt said:


+1
http://en.wikipedia.org/wiki/Honda_Pilot

I don't understand either why you would see a difference in performance unless the shiftpoints are dynamic based on the gear you are driving in (D5 vs D4). I mean if D5 doesn't kick in until 45 mph, why would you see any benefit to driving in D4 below that speed, for example?

I was baffled that I saw any benefit in driving in D4 below 45mph for that reason. I can't understand it but my X is a totally different car when going between D4 & D5 in this speed range. I can't help wonder if this difference has something to do with the TC failures. Perhaps, as you said, the shiftpoints are programmed differently. Maybe the factory set shiftpoints for D5 are causing above normal internal stresses. I don't know, thought I'd throw that out there.

Also, forget anything I said about the Pilot, 5-speed as confirmed with Honda's website.
 

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I agree the MDX behaves differently (better) when driven in D4. I only use D5 for highway use.

When in D5 around town it is always trying to get into overdrive and jumps around between 3-4 quite a bit.

When in D4 it is always in the right gear.
D5 usually requires a not so smooth downshift in order to even accelerate slightly.

2/3 of my commute is on a road with 55mph speed limit and traffic lights. D4 is perfect because it gives me just the revs I need to be in the power curve for passing acceleration at ~50mph. No downshift req'd = less wear on trans.
I'll pay the extra few bucks in gas to have power and a transmission/converter that doesn't need replacement.
 

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I tried this on the way home from work tonight and it did seem to make a diffrence. I will need to do some more experimenting though.

ts, what were some symptoms of your TC failures? I am having a surging sound around 1500 rpms going about 30-35 mph. It seems to disappear when I am in D4. I only noticed this after the car was in a rear end collision this summer and the exhaust was replaced. Ii can't tell if it is exhaust resonance or something else. Thanks for the help.
 

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The torque converter issue produces a rumble strip/lugging feeling. Its in too high a gear for the correct engine speed. While cruising between 30-45mph it may be in 5th gear, when it should be in 4th. I heard on some of the replacements they are doing ECU updates to change the shift points. No one has found out what exact changes are being made.
 

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Long time since I've post on here, surprised myself that I remembered my login info. :D

Now onto my input. My 05 MDX currently has 104k miles. I noticed that around 80-90k I too was getting that rumbling sound, sounded like wind rushed pass the front of the truck. I thought the trans was going so I started driving in D4. We also moved from NJ where the roads are pretty flat to GA where theres alot more hills. I will say that when driving in D5 at about 45-50 mph I would get that noise but it would go away when I got to 55-60+. Now in D4 I dont get the noise at all. Smooth driving.
 

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Discussion Starter #14
phins2rt said:
I tried this on the way home from work tonight and it did seem to make a diffrence. I will need to do some more experimenting though.

ts, what were some symptoms of your TC failures?
I was getting the harsh "rumble strip" noise from the front end. It's really obvious when it happens. Heard it explained a lot on this site. Then the day it happened I knew my problem right away. It almost feels like it's in too high a gear. I was getting it around 35-45mph. At this speed, it shouldn't have been in 5th, but felt like it was and wouldn't downshift.

RallyD - You explained it much better than I did. My tranny performs exactly the same. But when I'm in D4, it always hits the right gear. No awkward downshifts. I really don't give a dam what my gas mileage does by driving this way. It's cheaper than a new TC ($2200) or new tranny ($4000+). I'm hoping this helps me get more miles out of my X.
 

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ts8169 said:


I was getting the harsh "rumble strip" noise from the front end. It's really obvious when it happens. Heard it explained a lot on this site. Then the day it happened I knew my problem right away. It almost feels like it's in too high a gear. I was getting it around 35-45mph. At this speed, it shouldn't have been in 5th, but felt like it was and wouldn't downshift.
Thanks ts. I don't think I am experiencing what you were experiencing. Was the rumble strip noise constant or was it more of a pattern where you could hear for a second or two then it goes away for a second or two and then returns?
 

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Discussion Starter #16
If I was going steady at 35, then ease up lightly on the gas, the rpm's would fall to 1200 and it would happen. Then I'd take my foot off the gas and it would stop. Re-apply the gas and it would downshift and be fine.
 

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ts8169 said:
If I was going steady at 35, then ease up lightly on the gas, the rpm's would fall to 1200 and it would happen. Then I'd take my foot off the gas and it would stop. Re-apply the gas and it would downshift and be fine.
Thanks. I don't think that is what I am experiencing. It's probably something even more catastrophic!:rolleyes:
 

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So what exactly does the torque converter do?
 
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