Clubjazz - Honda Jazz & HR-V Forums
Honda Jazz Forums => Honda Jazz Mk4 2020 - => Topic started by: Dave T on August 01, 2024, 09:27:16 AM
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Had my Mk4 for 4 full months and overall really enjoy the car. Give it pretty much 9/10 score :)
However one issue. (Apologise if covered earlier thread but failed to find one.)
Driving along 65-70. Want to pull past slower moving stuff. Put foot down. No acceleration just high revving (like an old clutch slipping). This only seems to happen on a particular stretch M/way near me where there is a slight incline. On the flat or level.. elsewhere... there is No issue.
I rang my local Honda dealer re this... and advised the Jazz and the HR-V are all prone to this as part of the features of the CVT drive train ? Really ? Am I missing something here ? Told basically to adjust my driving style to accommodate this 'feature'. I am not trying to blast past anything... just pull away and it don't like it !
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Try putting it in 'SPORT' as you approach the incline, then floor it. See what happens.
I have driven a MK4 Jazz and owned an ehybrid HR-V.
You should get a pretty firm shove from the traction battery if you floor it at 60mph.
See what the charge level of the traction battery is after a few miles normal driving. if it doesn't look good get the dealer to check the battery and charging function.
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Driving along 65-70. Want to pull past slower moving stuff. Put foot down. No acceleration just high revving (like an old clutch slipping). This only seems to happen on a particular stretch M/way near me where there is a slight incline. On the flat or level.. elsewhere... there is No issue.
I rang my local Honda dealer re this... and advised the Jazz and the HR-V are all prone to this as part of the features of the CVT drive train ? Really ? Am I missing something here ? Told basically to adjust my driving style to accommodate this 'feature'. I am not trying to blast past anything... just pull away and it don't like it !
Honda probably didn't do its best with the misnomer e:CVT because it isn't a CVT!
What happens in your case:
Even if you were driving in "engine drive" mode before, the system will automatically switch to "hybrid drive" where the ICE is mechanically disconnected from the wheels and only drives the generator.
As your energy demand is high the ICE does its best to provide this by upping its revs to the maximum power output (which according to specs is 79 kW between 6000 and 6400 rpm) unsurprisingly making it sound "strained" and it will keep the revs at this level as long as the power demand doesn't go down.
Please also note that the main driving engine is electric with its maximum power output of 90 kW between 4'500 and 5'000 rpm which leaves a power gap of 11 kW. For very short spurts - and if the battery level allows it, the drive motor can draw additional power from the battery but not for long!
Long story short: In your example (cruising at 70 mph and demanding much power) the Jazz will only have 79 kW (provided via ICE / generator) at its disposition.
Your dealership is right: You will have to live with this or buy another (stronger) car.
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I've had this happen on rare occasions at motorway speeds, it's when you start climbing an incline with not much in the battery so the ICE has to generate all the electricity to get you up the slope at high speeds, I've just learnt to slow down a bit going up the hill when this happens to let the battery catch up then it's ok again.
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Try putting it in 'SPORT' as you approach the incline, then floor it. See what happens.
I have driven a MK4 Jazz and owned an ehybrid HR-V.
You should get a pretty firm shove from the traction battery if you floor it at 60mph.
See what the charge level of the traction battery is after a few miles normal driving. if it doesn't look good get the dealer to check the battery and charging function.
...This is what I have experienced too.
You will get more noise if you floor it between 60-70 but it will accelerate and it should be noticeable!
Sport will sharpen the response but won't provide anymore power.
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Yes it does happen as others have correctly described . If you select the power train dynamic display you can see the central cog showing when thw petrol engine is in direct drive mode . As the power demand increases it takes battery energy -if power demand decreases it channels energy back into the battery . I have found , impressively, that going up motorway inclines with a 3/4 full car load it will hold the mechanical direct time easily at 70 mph . If you then accelerate gently in most cases it wont change out of direct drive and that needs practise . Accelerate briskly and it will switch to pure electric with the petrol engine spinning to meet the power demands . If that happens going up a motorway incline it wont switch back unless you ease off or incline starts to level out . Irrespective of which mode the jazz is in it hasnt failed to accelerate nicely and heading to the other side of 100mph is IMHO well within its abilty. At the other end of the scale following a slow tractor 15mph up sutton bank in n yorks the jazz went up all tbe way in EV mode 3/4 loaded with just 3 20 second petrol engine topping up the battery on the ascent . And in 29 C afternoon heat with air con on low temp . You soon get used to it all and the electric motor is giving around 185ft lbs of torque which is a massive increase over the 90 ft lbs of my similiar size 1.4 petrol NIssan NOTE.
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Here is the power torque curve of the 2020 jazz. The electric motor has a higher max rotation circa 9,000 rpm with the power controlled to slope up in a linear way at low speed to its governed max . Torque electronically limited at low speed to
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Some math coming... A car cruising at 70 mph on flat ground might require maybe 20 kW of power (to overcome air resistance, tire rolling resistance etc.)
If driving uphill, it requires even more power:
For example driving at 70 mph (31 m/s) up a 10 % slope, the speed upwards would be 3.1 m/s.
Weight of Jazz 1250 kg * 9.81 m/s² * 3.1 m/s = 38 kW of power required driving uphill.
So in total it requires 20 kW + 38 kW = 58 kW to drive 70 mph up a 10 % slope.
Jazz can produce 79 kW of power so this still leaves 79 kW - 58 kW = 21 kW available for accelerating the car. So it should still be able to accelerate in that situation.
If you were driving up a steeper 16 % slope instead, then Jazz woudn't have enough power to maintain 70 mph and its speed would start to slow down.
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Given most uk motorway gradients have around a 5% max incline i have yet to have my jazz slowed by going uphill on dual carriageways let alone a motorway . :)
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How odd.
In over 14k miles of driving, mostly on motorways, I haven't felt any lack of urge when pressing the throttle.
A back-to-back comparison with a hired Peugeot 2008 GT on similar journeys felt no different except the Peugeot with a DSG autobox had to drop down a couple of gears.
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How odd.
In over 14k miles of driving, mostly on motorways, I haven't felt any lack of urge when pressing the throttle.
A back-to-back comparison with a hired Peugeot 2008 GT on similar journeys felt no different except the Peugeot with a DSG autobox had to drop down a couple of gears.
Same here, can't say I have noticed any change or lack of urge on the motorway(not ignoring the fact it is a relatively low powered car)
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I found that if you try to cruise at a fuel efficient 60mph/100 kph and then get slowed down even further by traffic the car may not be in an ideal power curve for climbing a long incline.
I have changed my driving style slightly to anticipate any incline ahead. If you temporarily speed up in advance , to maybe 70mph (or more :P) you can normally sail up any motorway incline without problem. Even if a truck decides to block the 'fast' lane by 'elephant racing' the speed normally remains fast enough that the car will still pull ahead reasonably well once he gets out of the way.
The car has a lot of torque and considering its only 1.5 litre copes well with steep climbs up mountain passes and overtaking.
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Never had an experience as described here regarding acceleration, always almost surprisingly swift in either B or d mode.
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I would get your drivetrain checked, if you not beating Audi's and BMW's then something is wrong.
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Same here, can't say I have noticed any change or lack of urge on the motorway(not ignoring the fact it is a relatively low powered car)
I don’t consider a car having 122hp, weighing just 1.2 tons, to be a low powered car,
Not so many years ago, that would have been the standard, for many typical small sports cars. (MG, Triumph & similar)
As others have said, the performance can be very surprising, to some boy racers who try it on. ;D
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Yes the big german 2 litre diesels do get a surprise by hiw quick the jazz can be out of a roundabout…😆
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I've not particularly noticed any lack of power when accelerating on an incline at 65/70mph. Without reading all the posts in this thread in detail, I don't think anyone has mentioned that at about 65mph the petrol engine drives the road wheels directly with a fixed gear ratio. (Like driving a conventional petrol engined car in top gear). If you accelerate at this speed the electric motor will add power to the transmission as needed to help deliver more power to the wheels.
This video explains it all very well: There are other videos which also explain it.
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If you accelerate at this speed the electric motor will add power to the transmission as needed to help deliver more power to the wheels.
Provided, of course, that the battery has sufficient stored energy to provide that power boost, and even if it does it won't do it for long. So it's entirely possible that there are circumstances in which the car won't accelerate, as reported by other owners.
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If you accelerate at this speed the electric motor will add power to the transmission as needed to help deliver more power to the wheels.
Provided, of course, that the battery has sufficient stored energy to provide that power boost, and even if it does it won't do it for long. So it's entirely possible that there are circumstances in which the car won't accelerate, as reported by other owners.
:-\ :-X
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Provided, of course, that the battery has sufficient stored energy to provide that power boost, and even if it does it won't do it for long. So it's entirely possible that there are circumstances in which the car won't accelerate, as reported by other owners.
That's not my understanding. I believe maximum power is achieved by the electric motors alone, with the ICE going to higher revs to deliver maximum generated electric power to the electric drive motors. I believe the ICE is used for direct drive via the clutch at a select range of conditions which optimise efficiency.
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Just reviewed a Honda technical presentation on the eHev system.
Between 50 and 75mph a Jazz uses direct ICE drive about 73% of the time. Below, mainly EV drive and above EV drive.
Interestingly it states the generator motor is 70Kw whilst the drive motor is 80Kw, so it would seem that to get maximum drive power some battery energy must be available.
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Interestingly it states the generator motor is 70Kw whilst the drive motor is 80Kw, so it would seem that to get maximum drive power some battery energy must be available.
I also think that's how it works, based on the numbers.
at about 65mph the petrol engine drives the road wheels directly with a fixed gear ratio. (Like driving a conventional petrol engined car in top gear). If you accelerate at this speed the electric motor will add power to the transmission as needed to help deliver more power to the wheels.
Yes, if you accelerate gently. But if you froor the pedal, then the fixed gear ratio between the petrol engine and the wheels disengages, and the engine revs up, so that it could generate maximum electricity, which the drive motor then uses to spin the front wheels.
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The clever part is that the power control can instruct the petrol engine to spin up to whatever rpm is required . Floor the accelerator and it will go to the rev limitor within a second or so , you dont have to wait for revs to build as you accelerate through the gears . Almost instant full petrol engine power available to genreate the electrical power . Also the modest sized HV battery can add quite a few kW for a few seconds ( and others may add their better knowledge ) id guess it could add 20 to 30kW if needed for 10 /15 seconds ?
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Looking at another thread https://clubjazz.org/forum/index.php?topic=13799.msg107929#msg107929 (https://clubjazz.org/forum/index.php?topic=13799.msg107929#msg107929)
our Jazz may be using these battery cells https://www.yuasa.co.uk/2016/05/2629/
(https://www.gs-yuasa.com/webdata/img//gs160711142215/img_gs_160711205315.jpeg)
Let's do some math...
48 cells * 3.6V per cell * 300A maximum current = 52 kW
So the battery could output a maximum power of 52 kW, but that's just the maximum allowed by battery manufacturer, and I don't think Jazz uses that much power from the HV battery.
If Jazz would use that much power from the battery, it would fully deplete the battery in just 60 seconds, even if the battery was fully charged to 100%:
5Ah / 300A * 3600 seconds/hour = 60 seconds.
But that's just the maximum. I guess Lincolnshire Rambler's guess in the post above is closer to what actually happens.
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I've not particularly noticed any lack of power when accelerating on an incline at 65/70mph. Without reading all the posts in this thread in detail, I don't think anyone has mentioned that at about 65mph the petrol engine drives the road wheels directly with a fixed gear ratio. (Like driving a conventional petrol engined car in top gear). If you accelerate at this speed the electric motor will add power to the transmission as needed to help deliver more power to the wheels.
This video explains it all very well: There are other videos which also explain it.
Thanks for linking the video, I have finally got my head around the transmission
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You should be out pulling AMG's (250 BHP) uphill, I noticed the new Jazz had a very special drivetrain during a test drive in 2020, it can dump all it's power to the road in an instant, it can play with the big boys. :P
As usual a video to back this up, driver is not me BTW.
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You should be out pulling AMG's (250 BHP) uphill, I noticed the new Jazz had a very special drivetrain during a test drive in 2020, it can dump all it's power to the road in an instant, it can play with the big boys. :P
As usual a video to back this up, driver is not me BTW.
IMO if that was a 3 or4 lane motorway the Jazz would have been left standing, not sure if it's a BMW or a Merc, Jazz driver stupidly tried an undertake and failed so resorted to an equally stupid overtake just to make a point
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...What a plonker! :o :-X :-[
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...What a plonker! :o :-X :-[
Who's the plonker, me or the Jazz driver ;) ;D
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You should be out pulling AMG's (250 BHP) uphill, I noticed the new Jazz had a very special drivetrain during a test drive in 2020, it can dump all it's power to the road in an instant, it can play with the big boys. :P
As usual a video to back this up, driver is not me BTW.
IMO if that was a 3 or4 lane motorway the Jazz would have been left standing, not sure if it's a BMW or a Merc, Jazz driver stupidly tried an undertake and failed so resorted to an equally stupid overtake just to make a point
With the Jazz's brakes and handling its relatively safe to do that, uphill at the start Hugo Splat had to back off because the lag of a petrol only engine and this lag can be seen during the attempted undertake but 250 bhp AMD is too much for the Jazz but never say die because the rich detest being beat by pleb in a Honda.
And remember two wrongs make a splat - Hugo Splat.
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Let's not get carried away about the performance of the Jazz. Foot to the floor away from the lights it can only just out accelerate an enthusiastic "white van man" in a modern van.
Add in the racket it makes when you floor it at any speed, its hardly an aural delight which encourages such behaviour.
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My latest Jazz, has been supplied with a Honda document entitled EC Certificate of Conformity.
This gives the following information, relating to power output .
Total net power 79Kw (ICE)
Maximum net power 90Kw (EV)
Maximum 30 minutes power 45Kw (EV)
Maximum speed 175 Km/h
I assume the 30min figure is average max power over 30min, presumably to control any overheating of the EV motor.
This translates to an average of around 60HP which I guess is more than adequate to cope with continuous Motorway driving.