To OD or not to OD

1.8-liter VVTL-i (2ZZ-GE) and VVT-i (1ZZ-FE) engine, transmission, exhaust, intake, and performance tuning discussions
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gdizzle
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To OD or not to OD

Post by gdizzle »

What is the rule for using OD? With it on all the time it seems fine. But with it off I notice the engine works harder. Am I supposed to have it on or off?o.g.
BryanC7020
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Post by BryanC7020 »

with OD on, the axle spin is greater than the gear spin, meaning it takes less work to go faster, hence better gas mileage. With it off you get direct throttle control, which is good for sport oriented driving and windy roads you want to play on, but aweful on gas mileage, since, as you said, the engine has to work harder to make the same speeds.
northvibe
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Post by northvibe »

i was always told when towing or on big mountains to use OD. otherwise i just drive with it off.
BryanC7020
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Re: (northvibe)

Post by BryanC7020 »

overdrive means the driveshaft to crankshaft/transmission spin is greater than 1:1, meaning that the driveshaft(s) are spinning faster than the engine is turning the crankshaft, meaning the car can run the same speeds at lower RPM. This, however, means you have less available HP at any given time unless you downshift, because of the lower revs you are out of your power band most of the time, whichi s why you drive with it off when you want to drive your car hard and need the HP at the ready.When the cams and pistons go up and down, they turn a shaft at the bottom of the V (or in our case, the I), it in turn turns the shaft in the transmission, which is connect either to a driveshaft, or in the case of AWD, a center differential that dictates how much power is sent to the front and back, and then a drive shaft. With OD on, the transmission engages gears that allow the driveshaft to turn faster than the crankshaft, which equals better gas mileage, but again, less available horspower unless you downshift to the throw the revs higher again.Personally, if I was towing something, I would turn OD off so I Could control the HP easier.
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millster
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Re: (northvibe)

Post by millster »

Quote, originally posted by northvibe »i was always told when towing or on big mountains to use OD. otherwise i just drive with it off.I think they told you backwards. The simplest way to approach this is to think of overdrive as what it is. A very "tall" gear designed to improve fuel economy at high speeds.Basically, the only time it would be undesireable is when you won't be holding a steady speed and don't want to have the tranny constantly shifting in and out of that final gear (city driving at speeds lower than 35MPH, hills, etc).That constant shifting can be hard on the tranny as well as potentially more harmful to fuel economy.
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northvibe
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Post by northvibe »

wait. OH YEAH!! LOL sorryhmm yea because its normally off wow..hmmmm im so out of it today. yea turn it on when towing....ok back to my corner
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joatmon
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Re: To OD or not to OD (gdizzle)

Post by joatmon »

overdrive is your top gear. Turn it off when you don't want to use the top gear, such as towing, or going down a mountain, or when it seems to keep upshifting/downshifting. Otherwise, probably almost all of the time, leave it on (overdrive ON means that the "O/D Off" light is not lit up) for best fuel economy at highway speeds. If you don't get going fast enough that it would shift into the top gear, it doesn't really matter.
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scherry2
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Re: To OD or not to OD (gdizzle)

Post by scherry2 »

I've always used overdrive as a passing gear when traveling down the interstate, hit the O/D button off, lots of passing power.
urbanmonkeygod04
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Re: To OD or not to OD (scherry2)

Post by urbanmonkeygod04 »

I remember in my Vibe, I always thought that when you hit the "OD" button it didn't really turn any overdrive off, it just downshifted a gear . . . OD off felt just like 3rd gear, and it never worked when you were in 1st through 3rd . . . so yeah.
tangerine
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Post by tangerine »

I always took OD off when I wanted to hit top speed. Seemed like it would struggle to get around 120 with OD on, where when off it just leaped up there.
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drunkenmaxx
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Re: (tangerine)

Post by drunkenmaxx »

Quote, originally posted by tangerine » Seemed like it would struggle to get around 120 with OD on,especially since your top speed would be 115!!!
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tangerine
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Post by tangerine »

My vibe had gone past 120 with no limiter kicking in many times, I even took a dealer mechanik out in it and did it and he said the limiter never kicked in on the car. Do the vibes even have one?
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drunkenmaxx
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Re: (tangerine)

Post by drunkenmaxx »

oh, it has one! believe you me.http://forums.genvibe.com/zerothread?id=7021
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ColonelPanic
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Re: To OD or not to OD (urbanmonkeygod04)

Post by ColonelPanic »

Quote, originally posted by urbanmonkeygod04 »I remember in my Vibe, I always thought that when you hit the "OD" button it didn't really turn any overdrive off, it just downshifted a gear . . . OD off felt just like 3rd gear, and it never worked when you were in 1st through 3rd . . . so yeah.That's because O/D is 4th gear. I'm with Sheldon on when to disable overdrive... I mainly do so when more power is needed. But also, when engine braking is needed, I will disable overdrive as well. Comes in handy when driving though hilly terrain, giving the breakes a rest...
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northvibe
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Post by northvibe »

ohhhh next time im on the hwy ill try OD off... i hit 115/116 and never felt the limiter.. i had to slow back down for a slow car in front of me though
Raven
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Re: (northvibe)

Post by Raven »

Before the untimely death of my Vibe, I was turning off the o/d anytime I wanted to zip around in traffic or on low to medium speed twisty roads. It makes for quicker acceleration and some engine braking like a standard. It eliminates the throttle lag when the transmission downshifts from o/d to drive. (P/S I may be ordering a new '06 Abyss 5 speed tomorrow to replace the demolished '04 Fusion auto.)
Jaycie685
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Post by Jaycie685 »

I remember asking this same question! In fact, it was the very first question I asked when I joined this site. I was lost as well!For normal driving, drive with OD on. That's why it's automatically on when you start the car. Now if you need extra power like say you're coming to an incline and you notice that your odometer is going backwards, then turn OD off and it switches gears to "Drive" which gives you more power to go faster but at the same time you're revving more rpms which also causes you to eat more gas.So to conclude, "OD on" is used for normal city and highway driving."OD off" is used when you need more power to go up an incline or when you're towing a heavier load or even when you want an extra push when taking off at the stoplight.Hope this helps!
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damronjr
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Re: (Jaycie685)

Post by damronjr »

Quote, originally posted by Jaycie685 »I remember asking this same question! In fact, it was the very first question I asked when I joined this site. I was lost as well!For normal driving, drive with OD on. That's why it's automatically on when you start the car. Now if you need extra power like say you're coming to an incline and you notice that your odometer is going backwards, then turn OD off and it switches gears to "Drive" which gives you more power to go faster but at the same time you're revving more rpms which also causes you to eat more gas.So to conclude, "OD on" is used for normal city and highway driving."OD off" is used when you need more power to go up an incline or when you're towing a heavier load or even when you want an extra push when taking off at the stoplight.Hope this helps! Very correct!
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tangerine
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Post by tangerine »

well then indeed odd. unless it was my tire size screwing my speedo up. there's a good excuse for my tickets i got in that car
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BOZACK
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Re: (tangerine)

Post by BOZACK »

Jaycie is correct. I leave min on all the time. Never had a reason to turn it off yet.Tangerine, you should get the Stealth color. It looks great.
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northvibe
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Post by northvibe »

ha....ha MUAHAHAHHAAH yes, i have to drive 130-140 miles tomorrow to go home for the weekend for a client. ill try this OD off for hwy passing...MUAHAHHAAH thnx
drunkenmaxx
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Re: (northvibe)

Post by drunkenmaxx »

Quote, originally posted by northvibe »ha....ha MUAHAHAHHAAH yes, i have to drive 130-140 miles tomorrow to go home for the weekend for a client. ill try this OD off for hwy passing...MUAHAHHAAH thnx youll be glad you did! w/a CAI, it makes exelleration on the highway sound like a raped ape!
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cknight725
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Re: To OD or not to OD (joatmon)

Post by cknight725 »

Quote, originally posted by joatmon »overdrive is your top gear. Turn it off when you don't want to use the top gear, such as towing, or going down a mountain, or when it seems to keep upshifting/downshifting. Otherwise, probably almost all of the time, leave it on (overdrive ON means that the "O/D Off" light is not lit up) for best fuel economy at highway speeds. If you don't get going fast enough that it would shift into the top gear, it doesn't really matter.Whew, good job joatmon -- I was begining to worry that nobody would get this one right!
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millster
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Re: To OD or not to OD (cknight725)

Post by millster »

Quote, originally posted by cknight725 »Whew, good job joatmon -- I was begining to worry that nobody would get this one right! I really must be invisible.
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scherry2
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Re: (northvibe)

Post by scherry2 »

Quote, originally posted by northvibe »ha....ha MUAHAHAHHAAH yes, i have to drive 130-140 miles tomorrow to go home for the weekend for a client. ill try this OD off for hwy passing...MUAHAHHAAH thnx well?
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