Torque converter losses, RPM, and fuel efficiency.

[LloydLynx]

So I was wondering if my efforts big toe driving is being canceled out by the torque converter slipping at low RPM. Accelerating at 2k and the tac doesn't really change across shifts. Accelerating at 3k or greater and you can notice the tac and engine RPM being affected by the shifts. So I'm wondering if accelerating lightly at low RPM is pissing away engine power through torque converter losses, effectively canceling out my hypermiling efforts.

It's an 02 four banger Ford Ranger.

[atxcyclist]

Things to keep in mind:

• Torque converters in modern vehicles have a ‘lockup’ at higher engine RPM, so the driveline losses are as little as possible on the highway and at cruising speeds.
• 2002 vehicles are getting old, so there’s likely other wear in your clutch packs, possibly buildup in the valve body, or pressure drop through your filter.
• I’ve driven a few Ford Rangers, both 4-cylinder and V6, automatic and manual, and the 4-cyl automatic ones are really being asked to do a lot; The torque converter is going to be really ‘loose’ because it has to leave enough driveline cushion in low revs to not load the engine too much.

 

[Rocketdog2112]

Have you checked your transmissions fluid level and condition of fluid? 

Is the fluid level correct (checked hot and in park on a level surface on most vehicles). 

 

Is the fluid red in color or is it dark and smells. Does it look like a strawberry shake (indication of water in the fluid) 

 

So when was the last time you did a fluid and filter change

 

Torque converters rarely wear out. The aforementioned lockup clutch can wear, but this is only noticeable at cruising speeds and rpm's when lockup is active. Other than the lockup clutch, there is nothing more mechanically in torque converter that can physically "slip". 

 

You can actually see the torque converter unlock and lockup by lightly and quickly tapping the brake pedal while at cruising speed. When you tap the brake pedal, you will see (if you have a tachometer) the engine rpm slightly increase when it unlocks, and slightly decrease when it locks back up. 

 

Torque converters work off of engine rpm and fluid pressure produced by the transmission oil pump. If the transmission cannot produce enough fluid pressure due to worn internal parts, the converter cannot function properly. 

 

Any adverse operational conditions such as slippage or odd shifting patterns below cruising speeds is an indication of the transmissions internal wear and oncoming failures. 

 

And a strong word of advice... 

Stay Away from and recommended so called transmission flushing services. They will do more harm than good. 

[LloydLynx]

9 hours ago, atxcyclist said:

Things to keep in mind:

• Torque converters in modern vehicles have a ‘lockup’ at higher engine RPM, so the driveline losses are as little as possible on the highway and at cruising speeds.
• 2002 vehicles are getting old, so there’s likely other wear in your clutch packs, possibly buildup in the valve body, or pressure drop through your filter.
• I’ve driven a few Ford Rangers, both 4-cylinder and V6, automatic and manual, and the 4-cyl automatic ones are really being asked to do a lot; The torque converter is going to be really ‘loose’ because it has to leave enough driveline cushion in low revs to not load the engine too much.

 

It hits overdrive at 35mph and lockup at 45mph. It almost feels like another shift when it happens, except that it becomes more stiff of a connection like a manual transmission.

What I wanna know is am I wasting my effort big toe driving from the loose fluid coupling at low rpm increasing torque converter losses? Would it be more fuel efficient accelerating more normally for higher rpm and tighter fluid coupling?

2 hours ago, Rocketdog2112 said:

Have you checked your transmissions fluid level and condition of fluid? 

Is the fluid level correct (checked hot and in park on a level surface on most vehicles). 

 

Is the fluid red in color or is it dark and smells. Does it look like a strawberry shake (indication of water in the fluid) 

 

So when was the last time you did a fluid and filter change

 

Torque converters rarely wear out. The aforementioned lockup clutch can wear, but this is only noticeable at cruising speeds and rpm's when lockup is active. Other than the lockup clutch, there is nothing more mechanically in torque converter that can physically "slip". 

 

You can actually see the torque converter unlock and lockup by lightly and quickly tapping the brake pedal while at cruising speed. When you tap the brake pedal, you will see (if you have a tachometer) the engine rpm slightly increase when it unlocks, and slightly decrease when it locks back up. 

 

Torque converters work off of engine rpm and fluid pressure produced by the transmission oil pump. If the transmission cannot produce enough fluid pressure due to worn internal parts, the converter cannot function properly. 

 

Any adverse operational conditions such as slippage or odd shifting patterns below cruising speeds is an indication of the transmissions internal wear and oncoming failures. 

 

And a strong word of advice... 

Stay Away from and recommended so called transmission flushing services. They will do more harm than good. 

The fluid is between pink and brown, no smell. It's at the point where I don't wanna change it for fear of finishing off an already worn out transmission. Unfortunately maintenance wasn't kept up by previous owners.

[Needfuldoer]

16 hours ago, LloydLynx said:

What I wanna know is am I wasting my effort big toe driving from the loose fluid coupling at low rpm increasing torque converter losses? Would it be more fuel efficient accelerating more normally for higher rpm and tighter fluid coupling?

You should get the best mileage by feathering the throttle just enough to maintain speed. I got 40 MPG out of an otherwise stock SOHC automatic Saturn SL that way many moons ago.

 

What kind of mileage are you getting? I've borrowed a 2003 single cab long bed Ranger with the 3.0 Vulcan V6 and the 5-speed automatic, and I managed to get about 18 MPG city, 22 MPG highway without too much effort. (It doesn't have a bed cover, and it has larger-than-stock wheels and tires. With the factory wheels and tires, the speedometer was actually reading about 10% fast.)

 

You've got the 2.3L Mazda 4 cylinder and the same 5 speed automatic transmission. You might be able to get better numbers than I did, but it's still a truck. (You might have lower gearing to help that little engine push that brick of a vehicle body through the air and get off the line with half a ton of load in the bed.) There's only so much you can do without going full hypermiler with DIY aero mods.

 

If fuel economy is top priority and you don't need to haul stuff, you're better off with a car. (You'd be surprised how much stuff you can fit in a hatchback. I've brought home framing lumber and 10 foot pipes in my Volt.)

 

16 hours ago, LloydLynx said:

The fluid is between pink and brown, no smell. It's at the point where I don't wanna change it for fear of finishing off an already worn out transmission.

A drain-and-fill won't destroy the transmission, but fresh fluid can expose existing problems. Friction material sloughed off the clutch packs and floating in the fluid basically acts like stop-slip. "Power flush" operations can cause issues by forcing debris deeper into the transmission though, so don't do that.

 

 

16 hours ago, LloydLynx said:

Unfortunately maintenance wasn't kept up by previous owners.

What have you done for maintenance so far? A new air filter (not a K&N), new spark plugs, Techron fuel system cleaner, and an Italian tuneup can make a big difference depending on how neglected it was.

[LloydLynx]

51 minutes ago, Needfuldoer said:

What have you done for maintenance so far? A new air filter (not a K&N), new spark plugs, Techron fuel system cleaner, and an Italian tuneup can make a big difference depending on how neglected it was.

When I inherited it, the brakes were lot rotted. It got an oil change, air filter, full tune up, and tires. Still gotta do the valve cover gasket because the spark plug hole seals are letting oil through. And gotta do brakes yet, but the pads are like 30% so I wanna get a bit more miles out of them.

[Rocketdog2112]

18 hours ago, LloydLynx said:

It hits overdrive at 35mph and lockup at 45mph. It almost feels like another shift when it happens, except that it becomes more stiff of a connection like a manual transmission.

Technically that how a lockup converter works. 

At cruising speed an oil pressure signal is sent to the converter causing the internal tubine assemblies to lock together creating a 1 to 1 drive ratio. 

It's normally a very gentle process that can't be felt. If yours is slamming or shuddering when going into lockup, it time for a new converter. 

[Vonrottes]

If you suspect excessive slip, you can always verify with a cheap OBD2 adapter and your phone using Torque, Scanlink, or whatever.
500rpm slip at the transmission input unlocked is not abnormal in my experience. lock up you will likely see less than 10 rpm slip.
depending on the vehicle the torque convertor could be as low as a like 1000rpm stall or up to like 2500rpm
(my S10 with a LS swap and stock silverado 4l60e with stock TC stalls at like 1200rpm, my girlfriends chevy cruze stalls around 2500rpm with traction control off)

feeling like a shift point when TCC lockup is normal I think most things I've driven is about a 250-500rpm drop.
(granted that experience is also only in GM vehicles)
 

if you feel the TC is fine the clutches in the transmission aren't excessively worn change the fluid/filter, I've done pan drops and filter replacements on several cars/trucks with 6l80e and 4l60e that saw significant improvement in shift performance and felt like it "tightened up" the gears. DO NOT have a flush done, just drain the pan and replace the filter/fluid (also make sure you clean out any friction material in the pan)

 
I have VERY limited experience with ford transmissions though, just a little bit with a 2000 Explorer with a 5R55E when it started having shift flares and slipping I recall my dad replacing the valve body and tightening the bands, but it still ended up crapping out. but it was throwing DTC for transmission solenoids, excessive slip, and all kinds of stuff. and this was back in like 2009 


Very different transmissions but the 4l60e in my S10 is from a 1999 Silverado has well over 200,000 miles on it (i bought it in 2012 with 180k).
I only changed the fluid/filter in 2018 when I installed a shift kit and replaced the separator plate. and I have not had any issues with it since.

[Beerzerker]

On 1/2/2024 at 6:04 AM, Needfuldoer said:

1: A drain-and-fill won't destroy the transmission, but fresh fluid can expose existing problems.

2: Friction material sloughed off the clutch packs and floating in the fluid basically acts like stop-slip.

 

3: "Power flush" operations can cause issues by forcing debris deeper into the transmission though, so don't do that.

 

 

 

I agree with the basics of this, some for different reasons but there is one point I'm not really agreeing with - At least to the exact point made about it and I'll just break it down as to why or why not.

1:
Yes, I 100% agree the very act of doing a Flush-N-Fill in itself won't destroy a trans but it can trigger things to make the trans fail.
It's been said if you are doing this to a trans that's never had it done before, DON'T and for good reason which leads to point 2.

2:
I can understand "Why" one would think about it in these terms BUT at the same time it's not beneficial and is related to why it's not a smart move to do a Flush-N-Fill to an older transmission.

Just bear with me here as to why I say this:
Reason is all the old clutch material worn off the clutches is packed in at odd places and just throughout the trans itself in general as a buildup of old crap/worn off clutch material, same basic thing as back in the old days you could pull the valve covers off of an engine that was ran on Quaker State motor oil and discover what looks to be "Sludge" coating everything.... And I mean everything and it's some nasty-looking stuff too.

Anyone that's seen it before knows the look it has - Unmistakeable in fact.

That was because the old Quaker State oil used back in the day had alot of paraffin in it (Wax) which was naturally occuring with where it came from (Pennsylvania crude) and that stuff would bake itself onto these surfaces and begin "Growing" spots that eventually coated everything as sludge - Hence the term "Quaker Sludge".

For a trans you won't see it like that but the after-effects of flushing the trans vs flushing an engine like that are the same.

Flushing a trans will start a process of breaking up these deposits and they will begin to circulate in large amounts, clogging fluid ports and the filter itself is subjected to becoming clogged with this debris in excessive amounts, which causes a lack of fluid flow where it needs to go under pressure. That's why it's been said repeatedly if doing a flush to a trans that's never been serviced before, it's not a good idea to do it and there are plenty of documented cases of it causing the trans to die a quick death not long after due to it burning out the clutches.

Do that to an old quaker-sludge engine and it's the same effect.
The build up starts breaking off in a swarm of chunks of different sizes and the oil filter becomes clogged, the oil pickup in the pan becomes clogged leading to a lack of oil flow in general, oiling passages also being clogged with little to no oil flow for things like rod bearings for example, which is bad all around no matter how you put it.

3:
Yes, I can see it stuffing some of the crap/debris deeper into trans components, packing it in but I can also see it contributing to the described effect stated above too, both of which are not good however you want to think about it. Anytime you have a deposit that's been broken up and repacked again it's not as prone to remain together as a clump or whatever term you'd like to use and will break apart more easily.

Subjected to being hit with fluid under pressure when the trans is in operation, it's easy to see why it would do that once softened or even broken up by fluid flushing, solvents used or whatever means is used to do the flush in the first place.

So.... If it has alot of miles on it and you're not sure about the servicing it's had before, think long and hard before you do it and if it's never been done before period - Just don't.

 

[Mark Kaine]

cant answer the question directly,  but this weirds me out lol. in my clio i shift at 7000rpm straight,  because that's where the red line is, it also sounds like an old formula 1 car at this point,  which is awesome. 

 

so my recommendation is sell your Toyota and buy a real, analog car instead then you don't have to think about this stuff

 

ps: im saying this weirds me out because im pretty sure my engine would insta stall if i shifted at 3000rpm, definitely not recommended by Renault lol