Stays out of Overdrive when cold?

[svtenthusiast]

Has anyone else noticed our cars are programmed to stay out of overdrive until the transmission has reached a certain temperature? My car never did this in the summer, but now that it has been colder outside it stays out of overdrive for awhile.

I don't think it is a transmission problem, because the time it takes to allow overdrive is dependant on the outside temperature (the delay is longer when temps are colder).

I am assuming there is a temp sender somewhere in the transmission, because I can warm the car up in the morning, and it still acts the same way (the transmission fluid does not warm up while the car is idleing).

Is there a way to override this, because it is killing my gas mileage.

 

[lancSHO]

I had the same issue and asked about it last winter. It's 'normal'. I don't know if Doug can do anything with the X-cal to make a fix.

 

[wuzzzer]

Are you talking about overdrive or talking about the torque convertor locking up? 4th gear is overdrive, does your car not shift into 4th? If so then something is definitely wrong.

If you're referring to how the torque convertor reduces engine rpms when it engages, it will only engage after the etransmission warms up. When its really, really cold out it can take quite a while for it to lock up. Its normal and yes it does make gas mileage worse, but so does the winter blend of gas that is used in many areas.

 

[SHOZ123]

Mine will not immediately shift to 4th when really cold. But almost always within a mile or two. The TC locking up can take up to 10 miles. This is with temps below 10F or so.

 

[Mr Anonymous]

Yeah, count your shifts, you should still see 3 shifts, but until the fluid is warm enough the TC won't lock.

 

[Axianator]

Is there a way to override this

Yes, although I would not recommend doing so.

 

[hoboprodigy-]

i feel my car pull thru 2nd, 3rd, into 4th, then the tc locks in around 5 miles up the road

 

[svtenthusiast]

Sorry I wasn't as clear as I should of been. Yes, it immediately shifts into 4th, but the TC does not lock until it warms up. Why did they design it this way? What benefit is there?

Other vehicles will lock the TC when cold, or with out as much as a warm up.

Axianator, how would you override this and why would you not recommend it?

Thanks for the replies.

 

[SHO#7]

When the TC is not locked it allows the fins to "slip" getting the fluid up to operating temps faster. After the fluid is warm the clutch will engage allowing lock up.

This is the same locking/unlocking that happens when you are on the highway with the AC on. It is a good thing to get rid of that, as too much locking and unlocking will increase wear on the TC clutch. However, the fluid needs to get up to temp before the clutch should engage.

Hope this helps

Mike

 

[cjaldrich]

Call me stupid, but it seems like mine doesn't shift into O/D when it's really cold outside too. The TC not locking up is basically like not allowing the full engine power to the tranny, right? Because maybe that's what is happening. I assume it's kind of like 'slipping' which would be why the RPM's are higher.

 

[svtenthusiast]

cjalrich, you are correct. It's not locking the TC for a consideriable amount of time, and from what I gather it is in effect "slipping" to allow faster fluid warmup. What I don't understand is why this process is so slow and why is it needed. Other vehicles I have driven don't have this much of a delay.

 

[Mr. SHO]

I have a 185*F oil t-stat on my cooler lines. I get up to operating temps within about 10 minutes on frigid mornings, and it keeps the temps around 190*F give or take. In summer, I have to remove the t-stat because the cooler can't hold the temps under 200*F when the t-stat keeps supplying it hot atf.