New fangled auto behavior
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Cargo Master
Joined: Apr 2003
Posts: 3,476
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From: Frequently frozen MN
New fangled auto behavior
Mike Allen over at Popular Science maintains that newer autos will kill the injectors when you lift off of the gas. Apparently another gas saving gimmick.
He further maintains that the tranny will continue to turn the engine as it rolls on down the highway. I wonder a little about this. I know that automatic trannys in the 50s had rear pumps which allowed then to be push started -- if you pushed them over 25 mph. ( There were a lot of jokes about morons getting the push car to 25 before reaching the vehicle to be pushed
)
Anyway, this leaves me with some questions.
Does an automatic these days actually turn the engine in a situation like this?
If it did, I would doubt that it would turn it very efficiently.
Assuming that you have a manual, does this scenario cause wear on the manual tranny? I've heard discussion about incorrectly loading the gears when they're driven by the wheels rather than the engine.
Does this new tech preclude push starting? Allen said something about the injectors being re-enabled when the engine was turning below idle speed, so maybe you can still push them.
I do remember 'kick starting' a few cars in my penniless youth-- until I could afford a new batt. Would make sure to park on a slope. Sometimes had to give it a little boost and jump in to get doing. Sounds like fun now.
ford2go
He further maintains that the tranny will continue to turn the engine as it rolls on down the highway. I wonder a little about this. I know that automatic trannys in the 50s had rear pumps which allowed then to be push started -- if you pushed them over 25 mph. ( There were a lot of jokes about morons getting the push car to 25 before reaching the vehicle to be pushed
)Anyway, this leaves me with some questions.
Does an automatic these days actually turn the engine in a situation like this?
If it did, I would doubt that it would turn it very efficiently.
Assuming that you have a manual, does this scenario cause wear on the manual tranny? I've heard discussion about incorrectly loading the gears when they're driven by the wheels rather than the engine.
Does this new tech preclude push starting? Allen said something about the injectors being re-enabled when the engine was turning below idle speed, so maybe you can still push them.
I do remember 'kick starting' a few cars in my penniless youth-- until I could afford a new batt. Would make sure to park on a slope. Sometimes had to give it a little boost and jump in to get doing. Sounds like fun now.
ford2go
Hotshot
Joined: Oct 2002
Posts: 18,488
Likes: 22
From: The Big, Oregon
Old news- most EFI cars do this. An auto tranny with a properly set up torque converter will turn the engine while decelerating as well. As long as the engine RPM stays above around 450, the pump will move enough fluid to keep the t/c full, and keep the chain going.
I know in both my car and my truck (both late 60's Fords) the auto tranny will provide almost as much engine braking as a manual. My truck has run out of gas before, I switched tanks while the engine was still being driven by the tranny, downshifted from drive to 2nd to 1st when the engine got gas and picked back up before going below the minimum pump speed.
Modern transmissions can lock up the torque converter, and the Ford Torqueshift locks and downshifts all the way down to a crawl to help slow the truck.
You can't push start from zero with the new autos either, the engine has to be turning to turn the pump and move the fluid to fill the t/c and apply clutches.
I know in both my car and my truck (both late 60's Fords) the auto tranny will provide almost as much engine braking as a manual. My truck has run out of gas before, I switched tanks while the engine was still being driven by the tranny, downshifted from drive to 2nd to 1st when the engine got gas and picked back up before going below the minimum pump speed.
Modern transmissions can lock up the torque converter, and the Ford Torqueshift locks and downshifts all the way down to a crawl to help slow the truck.
You can't push start from zero with the new autos either, the engine has to be turning to turn the pump and move the fluid to fill the t/c and apply clutches.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,739
Likes: 2,669
From: SE Florida
Originally Posted by ford2go
Mike Allen over at Popular Science maintains that newer autos will kill the injectors when you lift off of the gas.
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