2008 FEH Transmission acting strange
#11
03-07-2011, 09:00 AM
Re: 2008 FEH Transmission acting strange
When the Traction battery reaches its upper limit of programmed charge the energy of deceleration has to go somewhere. So they programmed a "Negative split" mode where the computer sends the excess energy that would have gone into charging the battery into spinning up the engine.
This is the equivalent of engine braking on a standard transmission. Note that an automatic transmission does this too but is far less apparent with a fluid coupling.
There is nothing in the FEH transaxle that would "slip" like you remarked on. Everything is done with gears & electric machine excitation. The "in & out" kind of feeling you're getting seems a bit odd to me, I haven't seen this at those temps near my place.
This is the equivalent of engine braking on a standard transmission. Note that an automatic transmission does this too but is far less apparent with a fluid coupling.
There is nothing in the FEH transaxle that would "slip" like you remarked on. Everything is done with gears & electric machine excitation. The "in & out" kind of feeling you're getting seems a bit odd to me, I haven't seen this at those temps near my place.
#12
03-07-2011, 11:50 AM
Re: 2008 FEH Transmission acting strange
It is sometimes possible to roll rearward at a stoplight on an incline with the gear in "D". I don't worry about it, just step on the brake pedal.
#13
03-12-2011, 07:40 PM
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Re: 2008 FEH Transmission acting strange
Everything the original poster said is normal. My 2005 behaves like this frequently.
Rest assured, nothing is "slipping". It is impossible in this type of transmission. The gears are always in mesh. ALWAYS.
What you feel is an illusion painted by your past experience in other cars.
What you feel is the regen cutting in and out... sometimes more abruptly than we'd like.
A bit of hesitation is felt when accelerating if your battery is cold and can't put out the amps you are used to. Hence, the weak(er) low torque Atkinsen engine has to do all the work, and its performance is poor at very low speeds.
Rest assured, nothing is "slipping". It is impossible in this type of transmission. The gears are always in mesh. ALWAYS.
What you feel is an illusion painted by your past experience in other cars.
What you feel is the regen cutting in and out... sometimes more abruptly than we'd like.
A bit of hesitation is felt when accelerating if your battery is cold and can't put out the amps you are used to. Hence, the weak(er) low torque Atkinsen engine has to do all the work, and its performance is poor at very low speeds.
#14
03-12-2011, 07:57 PM
Re: 2008 FEH Transmission acting strange
Everything the original poster said is normal. My 2005 behaves like this frequently.
Rest assured, nothing is "slipping". It is impossible in this type of transmission. The gears are always in mesh. ALWAYS.
What you feel is an illusion painted by your past experience in other cars.
What you feel is the regen cutting in and out... sometimes more abruptly than we'd like.
A bit of hesitation is felt when accelerating if your battery is cold and can't put out the amps you are used to. Hence, the weak(er) low torque Atkinsen engine has to do all the work, and its performance is poor at very low speeds.
Rest assured, nothing is "slipping". It is impossible in this type of transmission. The gears are always in mesh. ALWAYS.
What you feel is an illusion painted by your past experience in other cars.
What you feel is the regen cutting in and out... sometimes more abruptly than we'd like.
A bit of hesitation is felt when accelerating if your battery is cold and can't put out the amps you are used to. Hence, the weak(er) low torque Atkinsen engine has to do all the work, and its performance is poor at very low speeds.
As to the transmission, I believe that a conventional AT uses a planetary gearset, although implemented differently?
Anyway, as I said, I'm not worried about it, this is just a first-gen characteristic that I see occasionally, maybe once every other month or so.
#15
03-13-2011, 10:35 AM
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Join Date: Mar 2005
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Re: 2008 FEH Transmission acting strange
The regen cutting in and out when I am first moving the vehicle out in the morning? The point is not the weak acceleration (not really a factor here in SoCal), but that there is a distinct jerk after it goes maybe a couple of feet.
Well I believe we are talking about the same thing, but hard to know for sure without being there. Does mine do a wiplash inducing jerk? No. Does it occasionally lurch or surge, yes.
As to the transmission, I believe that a conventional AT uses a planetary gearset, although implemented differently?
No. Completely different here. I mean your engine is contstantly in mesh with the wheels and motors. Always. There is no "neutral" in this car either. The "N" on your gear stick is just for pretend. It is just a computer joy stick. "N" tells the car "do not generate power" but all the gears are still in mesh and turning. Even when towing. Your car has 3 power sources. A gasoline engine, A traction motor, and a generator motor. It is required for two out of three to be moving at all times.
Well I believe we are talking about the same thing, but hard to know for sure without being there. Does mine do a wiplash inducing jerk? No. Does it occasionally lurch or surge, yes.
As to the transmission, I believe that a conventional AT uses a planetary gearset, although implemented differently?
No. Completely different here. I mean your engine is contstantly in mesh with the wheels and motors. Always. There is no "neutral" in this car either. The "N" on your gear stick is just for pretend. It is just a computer joy stick. "N" tells the car "do not generate power" but all the gears are still in mesh and turning. Even when towing. Your car has 3 power sources. A gasoline engine, A traction motor, and a generator motor. It is required for two out of three to be moving at all times.
#16
03-13-2011, 06:16 PM
Re: 2008 FEH Transmission acting strange
"No. Completely different here. I mean your engine is contstantly in mesh with the wheels and motors. Always."
John, it sounds like the problem Steve is having is not normal but hard to be confirmed by a Ford Hybrid tech. Maybe a glitch in the warm-up strategy but not normal. The engine is not constantly in mesh with the wheels and the RPM's can be completely different. The amount of assist can cause jerks if programming is off during a certain mode of operation.
GaryG
John, it sounds like the problem Steve is having is not normal but hard to be confirmed by a Ford Hybrid tech. Maybe a glitch in the warm-up strategy but not normal. The engine is not constantly in mesh with the wheels and the RPM's can be completely different. The amount of assist can cause jerks if programming is off during a certain mode of operation.
GaryG
#17
03-14-2011, 12:50 PM
Re: 2008 FEH Transmission acting strange
"No. Completely different here. I mean your engine is contstantly in mesh with the wheels and motors. Always."
John, it sounds like the problem Steve is having is not normal but hard to be confirmed by a Ford Hybrid tech. Maybe a glitch in the warm-up strategy but not normal. The engine is not constantly in mesh with the wheels and the RPM's can be completely different. The amount of assist can cause jerks if programming is off during a certain mode of operation.
GaryG
John, it sounds like the problem Steve is having is not normal but hard to be confirmed by a Ford Hybrid tech. Maybe a glitch in the warm-up strategy but not normal. The engine is not constantly in mesh with the wheels and the RPM's can be completely different. The amount of assist can cause jerks if programming is off during a certain mode of operation.
GaryG
#18
03-14-2011, 03:08 PM
Re: 2008 FEH Transmission acting strange
GaryG
#19
03-18-2011, 04:37 PM
Re: 2008 FEH Transmission acting strange
I have a similar issue in my '05 sometimes trying to accelerate at highway speeds. The engine RPM's are always above 5,000 and all of a sudden the engine will lock-up with the wheel speed and the RPM's drops like a clutch that stops slipping. I get a drivetrain shutter when this happens also. Like you, it only happens about once a month so I'm not wasting my time at the dealer just yet.
GaryG
GaryG
#20
03-22-2011, 10:12 AM
Re: 2008 FEH Transmission acting strange
When E10 was mandated here in Florida the problem got real bad trying to accelerate without the RPM's getting out of control. This is a big reason the '05 had such a big decrease in MPG on E10. Programming may have changed in the '08 FEH, can anyone else confirm what I'm talking about?
GaryG
