Irish Taxi Forum
Public Area => Taxi Talk => Topic started by: Dr. Martin Gooter Bling on July 24, 2024, 05:02:59 pm
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my car has an unusual quirk. when you drive down a long hill for a protacted period around howth etc. when you drive on flat terrain again the engine idles very high around 3000rpm for a while. it's like the car wants to bleed off all the charge the hybird battery received when going down the hill or something. the way of combating it is to put the car in neutral and roll down the hill and feather the brake. that way the engine and the hybird battery are takin out of the game. i notice as well when i have an annoying cunt onboard and i'm really spanking the car the engine does the same at idle and roars upta 3000rpm for a while. my question is is it safe to slap the car in and out of drive and neutral while the car is moving on an auto car.
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I think that's what the B gear is designed for DMG.It uses the engine to brake going downhill rather than using the leccy motor and overcharging the battery.This way the battery can throw off any excess power and reduce excess wear on your brake pads.
Putting it in neutral might not do any harm but I'd be afraid I'd see a squirrel on Howth hill and forget I'm not in gear and have no accelleration if I needed it.
Next time try B mode and let us know what happens.
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as far as i can recollect it does the same in B mode.
i'll keep ye posted. thanks.
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The main difference should be that you can still accelerate in B mode in an emergency.If you drive around in B all day your efficiency will drop a fair bit but you probably know that anyways.
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i've never puttin the car in B mode.
only when tryin to diagnose this high revving at idle malarkey.
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If it's only happening going down big hills it's ok.
My old bolloxed Prius used to over rev when the battery was needing some attention.Usally it was a bogey battery cell and the car couldn't balance the pack so it would keep charging it.That's mmany years away hopefully if you've a newish car.
Just an aside but your battery gets its cooling from the cabin,the vent is in the rear footwell under the rear seat.Make sure you're filter is clean or the battery will be overheating as it can't get cooler air through.Also no harm in running the air con when it's roasting to keep the pack as cool as possible for longevity.
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as far as i can recollect it does the same in B mode.
i'll keep ye posted. thanks.
Mine does the same ....if I put it in " b" it reacts the same ...ie it revs for a bit after down the hill on the flat in howth ....if I set the cruise control to 50 kmph ...it does the same ...it could be fast idling on the flat for reasons I don't understand but
Ther must be a very good reason for it ... I wouldn't put it in neutral ever down a hill ...on a long one yu cud get brake fade ( not likely but possible ) ... I just trust Toyota have it all worked out an let the fast idle continue ...you won't overcharge the battery ... the computer thingy will cut it off charging ....but I'm still perplexed why it fast idles on the flat ... I tink it mite be to accelerate the coolant flow to cool the engine because even in drive the engine breaking is engaged which despite no fuel going to the engine the compression produces alot of heat .... anyways I think going down hill in idle is not a great idea oops
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(https://i.postimg.cc/GtvNP77H/Screenshot-20240724-221700-Chrome.jpg) (https://postimg.cc/RJVX4RzB)
It looks like the water pump is electric ...but not sure ...if it is ... then the fast idle is still a mystery oops
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what is "brake fade."
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what is "brake fade."
It's wen the coefficient of friction ( the grip of your pads on the disc ) reduces because of overheating to such an extent that you have no brakes ..for the car to slow down it must produce heat ...again this is energy exchange ( thermodynamics) ... in the hybrid the electric motor will convert some of the energy into the battery ...and some energy tru compression in the engine dicipated tru the exhaust ...but the energy must go somewhere...wen yu put the car in neutral ... you are overriding all of these systems of energy exchange and forcing all braking energy on the pads and discs to slow the car down ...this could result in brake failure in theory ... probly not in howth ...but likely in the alps ide imagine
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https://en.wikipedia.org/wiki/Brake_fade
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i can confirm it's even worse in B mode. the revs go up to 4000 and it starts on the descent before you even reach flat terrain again. the only way to drop the revs is to press the accelorator funny enough but why would you press the accelorator and want to go even faster on a very steep windy road?
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I use the cruise control doc an let the cars computer work it out .... it doesn't appear to rev on the flat as much ... or maybe I've learned to ignore it ...its not doing any harm for sure ... in fact it's probably nessessary
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Bean doin a bit goggling doc ...apparently/allegedly ..
The electric motor is turning over the petrol motor to use up the excess energy an prevent overcharging of the battery ... that would make alot of sense as to why the engine still revs on the flat after the hill
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"why would you press the accelorator and want to go even faster on a very steep windy road?"
We're all experienced on here but there is a school of thought that you are not in control if your vehicle when it is in neutral.If someone walked out in front of you and you swerved and braked you wouldn't be able to get off the middle of the road quickly without stalling and trying to find D mode.Very unlikely because we're all Top gun pilots but ya never know.
I suppose if you were in a heavier vehicle and your brakes failed there's nothing to slow you except the engine.The hand brake might not be much use on a big hill but who knows.
If the electrical system ever fails(extremely unlikely in a Toyota)your brakes aren't power assisted anymore and you'd quickly notice how shite they become.It used to happen to me very rarely if I didn't put the big orange safety hybrid battery plug in all the way after I had it out of the car.Scary but unlikely unless you were tampering with the vehicle.
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Does your prius' have a rev counter? Mine doesn't. Or an oil gauge. Never noticed the over rev thing meself and I do be up the mountains a lot as I live right beside them. Or when I used to do school runs I used the back road between Rathcoole and Saggart which has an extremely steep hill at both ends. Is it only on particular models this happens?
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I think DMG is in one of them new Corolla hybrids.They don't need the rev counter or a handbrake but Toyota put them in so maybe don't seem too strange to the new hybrid drivers coming from a diesel or petrol.
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..... We're all experienced on here but there is a school of thought that you are not in control if your vehicle when it is in neutral. .....
I'd go along with MFH on this, never a good idea to let the car control itself.
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The B thingy works well on steep hills.
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it does work and you can feel the car being anchored but it makes the engine scream upta 4000rpm which is very unnerving. it's like going down a very steep hill in first gear on a manual car it would do the same.
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Try the adaptive cruise control down hill doc ... the steady decend seems to work better... for me anyway ...
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The engine revving is probably just more noticeable as they're fairly quiet most of the time.You do become very aware of noises that you wouldn't have heard in a diesel.Same with the EVs.Putting tape over the rev counter might work also..
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The engine revving is probably just more noticeable as they're fairly quiet most of the time.You do become very aware of noises that you wouldn't have heard in a diesel.Same with the EVs.Putting tape over the rev counter might work also..
Putting the car in for a battery health check wouldn't do any harm. It's free AFAIK with Toyota.
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The engine revving is probably just more noticeable as they're fairly quiet most of the time.You do become very aware of noises that you wouldn't have heard in a diesel.Same with the EVs.Putting tape over the rev counter might work also..
Putting the car in for a battery health check wouldn't do any harm. It's free AFAIK with Toyota.
Dennis mahoney Kilbarrick charged me 100 quid for battery check every second service under Warrenty ....has that changed ?
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The engine revving is probably just more noticeable as they're fairly quiet most of the time.You do become very aware of noises that you wouldn't have heard in a diesel.Same with the EVs.Putting tape over the rev counter might work also..
Putting the car in for a battery health check wouldn't do any harm. It's free AFAIK with Toyota.
Dennis mahoney Kilbarrick charged me 100 quid for battery check every second service under Warrenty ....has that changed ?
I dropped the service manager to Clarehall. it was he who told me the battery health check was free—he said to ask for Dunner IIRC.
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The engine revving is probably just more noticeable as they're fairly quiet most of the time.You do become very aware of noises that you wouldn't have heard in a diesel.Same with the EVs.Putting tape over the rev counter might work also..
Putting the car in for a battery health check wouldn't do any harm. It's free AFAIK with Toyota.
Dennis mahoney Kilbarrick charged me 100 quid for battery check every second service under Warrenty ....has that changed ?
I dropped the service manager to Clarehall. it was he who told me the battery health check was free—he said to ask for Dunner IIRC.
Nice one ...but I'm sure ther are conditions...not mad about that place
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The engine revving is probably just more noticeable as they're fairly quiet most of the time.You do become very aware of noises that you wouldn't have heard in a diesel.Same with the EVs.Putting tape over the rev counter might work also..
Putting the car in for a battery health check wouldn't do any harm. It's free AFAIK with Toyota.
Dennis mahoney Kilbarrick charged me 100 quid for battery check every second service under Warrenty ....has that changed ?
I dropped the service manager to Clarehall. it was he who told me the battery health check was free—he said to ask for Dunner IIRC.
Nice one ...but I'm sure ther are conditions...not mad about that place
Try David Stokes Motors. https://www.chargedhybrid.ie/ (https://www.chargedhybrid.ie/) I bought the Prius hybrid battery from them. They're nice people to deal with. Josh replaced the battery in my 131 Prius in about 30 minutes.
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The only thing about the battery test is there's nothing they can do except replace the battery if it's bolloxed.There's no software that can modify bogey cells to make them behave differently.So Toyota will give you a battery check and extend the warranty....but only if it's not bolloxed after they've tested it.Not quite a scam but more for peace of mind.
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i was up in howth late last night no traffic perfect oppurtunity.
i went up the summit pub and turned right back down the hill set the adaptive cruise control to 50 and let the car drive.
it behaved itself and i hadta tap the breaks a few times and restart the adaptive cruise control again.
i thought i was on a winner when just approaching the abbey tavern the car started screaming upta 4000rpm for the next 5 minutes.
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i was up in howth late last night no traffic perfect oppurtunity.
i went up the summit pub and turned right back down the hill set the adaptive cruise control to 50 and let the car drive.
it behaved itself and i hadta tap the breaks a few times and restart the adaptive cruise control again.
i thought i was on a winner when just approaching the abbey tavern the car started screaming upta 4000rpm for the next 5 minutes.
...yea but it won't do any harm ...as I said I tink (99% sure) its burnin off excess energy stored in the battery from goin down the hill ...plus wen it's screaming it isn't using any petrol if yur worried bout fuel consumption...the electric motor is driving the engine
....its protecting yur battery ...let it scream away
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B in Toyota (I've only ever seen it in Toyotas anyway) is for Engine Braking - which is supposed to reduce/eliminate coasting. I think the theory is to replicate what a downward gear change with little or no braking would achieve on a manual (or clutched auto) car so increased revs would seem "normal"... I guess it's not beyond the realms of possibility that the car actually engages B itself while (apparently) in D if it detects no acceleration on a sharp decline or some such?
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B in Toyota (I've only ever seen it in Toyotas anyway) is for Engine Braking - which is supposed to reduce/eliminate coasting. I think the theory is to replicate what a downward gear change with little or no braking would achieve on a manual (or clutched auto) car so increased revs would seem "normal"... I guess it's not beyond the realms of possibility that the car actually engages B itself while (apparently) in D if it detects no acceleration on a sharp decline or some such?
Yea is does rat engage engine braking itself .... why the option for b is ther not sure ....it cud be for ya to prempt the car doin it if yu had 4 fatties in the car or more likely give ya the manual option going down an icey or snowy hill ide imagine
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I think B mode is to stop the brakes heating up too much going down a long hill.Not the likes of Howth hill but some countries that have a few miles of downhill mountain driving like in the US.
I think I read it in a manual a long time ago.