Hello i own a E89 3.0 sDRIVE with a 6hp transmission I'm not sure if i have got a problem or not when I'm driving at 30 mph the car is in 4th and the engine Revs are a round1600 rpm the same at 40 the car is in 5th and the Revs are at1600 can anyone tell me if this is normal or is there a problem with the transmission
ZF 6HP transmission
- Thread starter FLATSPOT
- Start date
It just seems like it wants to be in fifth at 30 mph and sixth at 40 mph just to bring the revs down a little if you drive it in manual mode you can put it in fifth at 30 mph and sixth at 40 mph the revs come down to 1200 the car feels happy at that its not labouring the 3.0 E85 I use to own would be in top gear at 30 mph and the revs were at 1200 that was a 5 speed auto
FLATSPOT said:
I think that the gearbox knows best!
Yes you can force the gearbox to change up to a higher gear - it’s just like a cyclist with strong legs, he can push the pedals using his big strong legs - but gets better efficiency when he uses a lower gear with a good cadence.
Let the engine spin and let the box do it’s thing - 1600 isn’t excessive!
Hi to all 6HP owners........
Better late than never I hope.....
[I just tried to send this to ZF but their enquiry form wouldn't work....]
At min throttle on level, 6HP shows 1500rpm at 50kph
How can this give most economical BMEP from the engine?
Even the 1.3 Honda Jazz CVT gives 60 kph at 1500 rpm level cruise [ 5.2L /100km urban] from higher BMEP>>>>>Lower SFC.....
Your claims regarding low speed TCC engagement don't seem to apply in practice.....
There appear to be millions of cars running very smoothly but burning vast amounts of fuel unnecessarily
How this helps with all the climate hysteria is not at all clear.....
Better late than never I hope.....
[I just tried to send this to ZF but their enquiry form wouldn't work....]
At min throttle on level, 6HP shows 1500rpm at 50kph
How can this give most economical BMEP from the engine?
Even the 1.3 Honda Jazz CVT gives 60 kph at 1500 rpm level cruise [ 5.2L /100km urban] from higher BMEP>>>>>Lower SFC.....
Your claims regarding low speed TCC engagement don't seem to apply in practice.....
There appear to be millions of cars running very smoothly but burning vast amounts of fuel unnecessarily
How this helps with all the climate hysteria is not at all clear.....
Scottish Borders
I haven't dared to try sport mode.....this could only make downshifts occur at even lower RPM/lighter throttle....
With petrol at current prices I could go broke...
I've also tried disconnecting the battery & then doing the 'adaptations'
The car is actually doing better than factory-claimed economy but I drive light-footed urban anyway...
There seem to be numerous strange behavior patterns with this trans. reported on other forums/fora but NOBODY can remap the TCM
Cheers.
With petrol at current prices I could go broke...
I've also tried disconnecting the battery & then doing the 'adaptations'
The car is actually doing better than factory-claimed economy but I drive light-footed urban anyway...
There seem to be numerous strange behavior patterns with this trans. reported on other forums/fora but NOBODY can remap the TCM
Cheers.
The ZF6HP in the E89 TCU can be remapped using xHP…
I’m struggling to understand what your specific issue or concern is?
These boxes have several different shift programs based on which mode they are in, plus adaptions..
How many miles has the car done?
How long / how many miles have you driven?
Has this situation suddenly appeared?
I’m struggling to understand what your specific issue or concern is?
These boxes have several different shift programs based on which mode they are in, plus adaptions..
How many miles has the car done?
How long / how many miles have you driven?
Has this situation suddenly appeared?
Apology....Confession...Explanation....
In reverse order.......
To B21 The 6HP is not actually in a BMW so XHP remap not poss.
This discussion started by FLATSPOT was the only ref. I could find to this problem [which appears to refute claims about the 6HP.. e.g.... 'That’s why we get decent mpg from this tranny. In other words it is more like a manual tranny with torque converter working only at very low speeds and low rpm."................https://www.bavlogic.com/?p=3738]
Specific issue or concern is that, like the starting post by FLATSPOT for this topic I find the shift points far too high for normal driving, [e.g. the Subaru XV 2L does 1000 rpm at 30 mph level cruise] thus causing far higher fuel consumption than necessary.
BMEP is too low so SFC is too high..........
https://www.researchgate.net/figure/Brake-specific-fuel-consumption-BSFC-vs-BMEP-a-at-1500-rpm-b-at-3000-rpm_fig1_273986854
I've only owned the trans for a few months so I don't think the problem is recent.
To hopz.121 The car has done 56000 miles so no servicing should be needed.....
Cheers . .
In reverse order.......
To B21 The 6HP is not actually in a BMW so XHP remap not poss.
This discussion started by FLATSPOT was the only ref. I could find to this problem [which appears to refute claims about the 6HP.. e.g.... 'That’s why we get decent mpg from this tranny. In other words it is more like a manual tranny with torque converter working only at very low speeds and low rpm."................https://www.bavlogic.com/?p=3738]
Specific issue or concern is that, like the starting post by FLATSPOT for this topic I find the shift points far too high for normal driving, [e.g. the Subaru XV 2L does 1000 rpm at 30 mph level cruise] thus causing far higher fuel consumption than necessary.
BMEP is too low so SFC is too high..........
https://www.researchgate.net/figure/Brake-specific-fuel-consumption-BSFC-vs-BMEP-a-at-1500-rpm-b-at-3000-rpm_fig1_273986854
I've only owned the trans for a few months so I don't think the problem is recent.
To hopz.121 The car has done 56000 miles so no servicing should be needed.....
Cheers . .
axelleveau
Member
Age of the oil and adapatation is unlikely to affect ups and down shift maps, they would mainly affect the valves controls, clutches and how jerky the shifts are.
Shift maps are calibrated by the car manufacturer and result in an engine RPM vs vehicle speed dependant on the diff ratio as well as tyres. They are a difficult comprimise between fuel economy, responsiveness and NVH. There probably is a way to bias this more towards what you'd like but it does not mean there is a greast consiparcy between ZF and the car maker
Shift maps are calibrated by the car manufacturer and result in an engine RPM vs vehicle speed dependant on the diff ratio as well as tyres. They are a difficult comprimise between fuel economy, responsiveness and NVH. There probably is a way to bias this more towards what you'd like but it does not mean there is a greast consiparcy between ZF and the car maker
Hopz121:
Re ATF change.......There is nothing wrong with the smoothness etc. of the trans.
Most car makers claim for the 6HP: 'Sealed for life',.........[The drain plug is VERY difficult to undo.]
axelleveau:
I agree with you 100% including 'great conspiracy between ZF and the car maker'
BUT There is a serious Automotive-engineering design issue here in that cars are NOT getting minimum practicable CO2 emissions which will hasten the greenies' efforts to kill the car as we know & enjoy it.
I for one [as well as FLATSPOT above] don't enjoy driving when the trans. kicks down at the lightest touch on the accelerator..
More cheers...................[I'll do an example calculation to clarify the point.]
Re ATF change.......There is nothing wrong with the smoothness etc. of the trans.
Most car makers claim for the 6HP: 'Sealed for life',.........[The drain plug is VERY difficult to undo.]
axelleveau:
I agree with you 100% including 'great conspiracy between ZF and the car maker'
BUT There is a serious Automotive-engineering design issue here in that cars are NOT getting minimum practicable CO2 emissions which will hasten the greenies' efforts to kill the car as we know & enjoy it.
I for one [as well as FLATSPOT above] don't enjoy driving when the trans. kicks down at the lightest touch on the accelerator..
More cheers...................[I'll do an example calculation to clarify the point.]
clintel said:
ZF say who designed and manufactured the gearbox say otherwise….. but what would they know :lol:
New seals, gaskets and oil made a decent difference to mine and then after that I XHP’d it which improved it even further.
I assumed you were the original poster which you aren’t and my original response was aimed at the OP. I only have experience of this gearbox in BMW’s so not sure what your issues are. May discuss it with ZF or your car manufacturer and see what they suggest.
Best of luck with it all.
I have the same problem as the OP had earlier but he probably sorted it out one way or another long ago..
I'll try ASAP to explain the technical issue [not performance / maintenance] which I've tried to find info about.
Your forum is the only one discussing the 6HP AFAIK so I was pleased to find it
More & more cheers...........
I'll try ASAP to explain the technical issue [not performance / maintenance] which I've tried to find info about.
Your forum is the only one discussing the 6HP AFAIK so I was pleased to find it
More & more cheers...........
Apologies for delay....
My answer to ronk
Of course the gearbox knows NOTHING.......It does what its programmers have instructed it [Realistically or otherwise] to do...
Human leg muscles, however strong, rely on a carbohydrate fuel / oxygen mixture from the human intake system . A cyclist can only continuously pedal as strongly as the blood supply to the leg muscles will allow....
The pistons & connecting rods in an engine can operate at full load indefinitely because they can be fed the required hydrocarbon fuel / oxygen mixture continuously by the intake system..
The amount of work required per engine revolution is not a fixed % of the work done by the expansion of the burning mixture...At full throttle the work done per revolution is much greater than the work needed to turn the crankshaft but at idle / very light throttle the net work done per revolution by combustion is a much smaller % than at full throttle.
A Diesel engine is more economical mainly because it is not throttled at all....
The more fuel burnt [completely] per revolution the more fuel economy is obtained because the work needed to turn the engine is smaller relative to the work done by the burning mixture.
The more fuel burnt per revolution; the more net work done, hence the more power per RPM and the further the car will go per drop of fuel....
I hope this is starting to indicate what my puzzlement [like that of the OP] is about
Cheers
My answer to ronk
Of course the gearbox knows NOTHING.......It does what its programmers have instructed it [Realistically or otherwise] to do...
Human leg muscles, however strong, rely on a carbohydrate fuel / oxygen mixture from the human intake system . A cyclist can only continuously pedal as strongly as the blood supply to the leg muscles will allow....
The pistons & connecting rods in an engine can operate at full load indefinitely because they can be fed the required hydrocarbon fuel / oxygen mixture continuously by the intake system..
The amount of work required per engine revolution is not a fixed % of the work done by the expansion of the burning mixture...At full throttle the work done per revolution is much greater than the work needed to turn the crankshaft but at idle / very light throttle the net work done per revolution by combustion is a much smaller % than at full throttle.
A Diesel engine is more economical mainly because it is not throttled at all....
The more fuel burnt [completely] per revolution the more fuel economy is obtained because the work needed to turn the engine is smaller relative to the work done by the burning mixture.
The more fuel burnt per revolution; the more net work done, hence the more power per RPM and the further the car will go per drop of fuel....
I hope this is starting to indicate what my puzzlement [like that of the OP] is about
Cheers