Reluctance of the car to get moving - No response from the accelerator with DSG

[wai]

G'day,

I may have a partial answer to the issue raised by some regarding an apparent reluctance for the car to get moving (i.e. no response to the throttle).

I have a Caddy Maxi Life with the 7-speed DSG (recall has been carried out). For various reasons I have to left foot brake. The other day, on my way home after work, I was travelling on a straight level stretch of road near my house when I had to "tap" the brake pedal. I had not come completely off the accelerator, but when I pressed the accelerator, there was nothing for a good 1/2 second. The accelerator pedal was being pressed, but no response from the engine. Naturally I pressed a bit more, and then all of a sudden, the system kicked back in, and launched me forward.

After thinking about it for a while, I suspected it to be an issue with "Brake Throttle Override" because when I tapped the brake, the engine suddenly dropped revs. Because I had not come fully off the accelerator, the BTO decided to override the accelerator input to allow maximum braking. The problem seems to be that the BTO then waits around 1/2 second (which can feel like ages) after the brake is released to hand control back to the accelerator.

I have since tried this with a few variations and it confirms it is the BTO that is the culprit.

If you come right off the accelerator and apply the brake, you have control of the accelerator immediately. It is only if you apply the brake before you have come right off the accelerator that the BTO kicks in and you have no control of the accelerator for around 1/2 second after coming off the brake.

Maybe this explains why people complain about having no "drive" on entering a roundabout or turning right at an intersection. It could well be they have applied the brake before coming fully off the accelerator, and then tried to accelerate away immediately.

It should not happen this way as the ECU will know that the vehicle is moving.

Anyhow, it's just an observation. Any thoughts?

[h100vw]

G'day,

I may have a partial answer to the issue raised by some regarding an apparent reluctance for the car to get moving (i.e. no response to the throttle).

I have a Caddy Maxi Life with the 7-speed DSG (recall has been carried out). For various reasons I have to left foot brake. The other day, on my way home after work, I was travelling on a straight level stretch of road near my house when I had to "tap" the brake pedal. I had not come completely off the accelerator, but when I pressed the accelerator, there was nothing for a good 1/2 second. The accelerator pedal was being pressed, but no response from the engine. Naturally I pressed a bit more, and then all of a sudden, the system kicked back in, and launched me forward.

After thinking about it for a while, I suspected it to be an issue with "Brake Throttle Override" because when I tapped the brake, the engine suddenly dropped revs. Because I had not come fully off the accelerator, the BTO decided to override the accelerator input to allow maximum braking. The problem seems to be that the BTO then waits around 1/2 second (which can feel like ages) after the brake is released to hand control back to the accelerator.

I have since tried this with a few variations and it confirms it is the BTO that is the culprit.

If you come right off the accelerator and apply the brake, you have control of the accelerator immediately. It is only if you apply the brake before you have come right off the accelerator that the BTO kicks in and you have no control of the accelerator for around 1/2 second after coming off the brake.

Maybe this explains why people complain about having no "drive" on entering a roundabout or turning right at an intersection. It could well be they have applied the brake before coming fully off the accelerator, and then tried to accelerate away immediately.

It should not happen this way as the ECU will know that the vehicle is moving.

Anyhow, it's just an observation. Any thoughts?

I don't believe it's a fault with the car. The ECU would never expect throttle and brake inputs at the same time. It's not normal driving practice.

I appreciate that you may have to brake with your left foot for some reason, but an impressively high percentage of the population don't and that is how the car is designed.

If you are using 1 foot to drive the car, you couldn't cause this issue to occur.

Gavin

[wai]

I'm not saying that there's anything faulty. It is as designed, just that if you do happen to use your left foot to hold the car this could happen. Many who normally use just one foot in an auto/DSG do use the left foot in some circumstances. Also, in a manual, there are those who might tap the brake with the left foot or even heel/toe which will see both active at the same time.

Incidentally, I have to left foot brake as a result of a very serious road accident back in 1975. The knee has deteriorated to a point where I could not guarantee I could get to the brake. I can drive a manual, just that for me it was a much better proposition to switch to left foot braking in a DSG/auto to be sure the brake was applied.

As I said, an observation, and if people can understand how and why things happen, it could help.

[tigger73]

You can get left foot braking enabled in some ECU tune/Haldex controller upgrades if you're that concerned about having this feature.

As Gavin says 99.9% of people just drive with the one foot and so this is how the car is designed to work.


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[MGV]

I would guess the percentage is not that high... I spend a lot of time on the road or the side of the road (surveyor) & there are often people who haven't learned to drive properly (not you, wai !) that drive around with their left foot resting on the pedal, activating the brake lights while they accelerate with the right...

[tigger73]

Ok 95% then. Perhaps this is a feature to teach these 5% of people to take their foot off the brake when they're driving.

Wonder if there is a VCDS option to enable/disable this function....


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[Umai Naa!!]

My advice would be, that if you have to hold the car stationary, or need to prevent it from rolling away while you're doing a low-speed manouvre, utilise the park brake*




*Those with an electronic park brake, ignore this.

[Sunny43.5]

I have a theory as well , VDud stupid technology , there so many people who seem to think that DSG problems are related to how we drive them . On a personal note I am not a fan cannot stand the van coasting down hill revving its tits off because the technology from engine to auto oops sorry DSG tells it to do so . Someone wrote that in this circumstance we should change it manually , sorry that defeats the whole idea of it being an automatic oops DSG . If I wanted a manual I would have bought one having three different systems in side one box is a recipe for eventual disaster . Then there is the known problem of driving in stop start traffic apparently it will wear out the clutches prematurely if you just keep crawling along stopping and starting and again another idiot claimed that we should be shifting to neutral each time what a crock !! VW told a taxi company in Sweden not to use one model VW as taxis as the DSG would not stand up to the traffic rigors . The recall of DSG's in Japan was blamed on wait for it stop start traffic and my favourite VW fopaux Japans HOT CLIMATE !!! Of all the documentaries I have viewed about Japan I have never seen or heard of any deserts in Japan , hmmm makes you wonder .

[MGV]

^^ The definition of 'rant' !

[Sunny43.5]

Yes guilty but if you had been on the receiving end of a bill for $11000 for a rebuild of one of VW's auto nightmare's then a rant is what you do !! , then you can add in the fact that because the van in question was an automatic it was the cause of a dealer who blatantly used that excuse to offer no money as a trade in . I will explain after only 135000 kays the auto failed why because inside was a filter that had become blocked and VW refused to service the auto and replace that filter Sealed For Life was their excuse . so $11000 was the bill along with other work done in the same month total spend in one month $14000 then when I decided to trade it the valuer at a VW dealer told the salesman that because it was an auto he "would no trust it " guess how much they offered for a one owner T5 135000 kays spot on condition between $4000 and $8000 so $14000 on repairs to then loose even more money give me a break please Rant Yes .

[tigger73]

I would have thought a decent workshop would point out the cost of repairs vs the value of the vehicle before carrying out the work. Particularly as this was a dealer.


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[gazzmo]

Guilty of left foot braking and placing the DSG in neutral at red traffic lights, I have experienced the dreaded dead accelerator pedal so I am going to use the hand break in future.

[MGV]

Sorry, Sunny43.5... Didn't realize you were out of pocket so much. Rant justified.

[tigger73]

Yes I think it's a disgrace when someone who has a current model vehicle and serviced with the dealer as per the schedule can have the cost of repairs more than the value of the vehicle. It should have been written off and joined the scrap heap. That shouldn't happen to a vehicle that is so new.


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[Sunny43.5]

Thanks guys it makes me feel better with some support , Vw just got me offside with their attitude to several inquires over the last couple of years with the van in question and our new one [yes I did buy another ] and still have to sell the old one , anyone interested in a T5 Transporter see here [/URL][/IMG]