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-   -   Vento AT acceleration problem (https://www.team-bhp.com/forum/technical-stuff/105998-vento-acceleration-problem.html)

Posting this on behalf of a non-member friend who is facing a problem with his Vento AT Highline late-2010 model.

The car was purchased in Feb this year. There were no obvious problems in the first 4 months: it went effortlessly to speeds of up to 140-150 or so without any issues.
Then one day the car had to be braked, HARD, from a speed of about 120 kmph. ABS kicked in, the car slowed to an almost-crawl, but there was no impact.

After this close shave the car has not been what it was earlier. It refused to exceed speeds of 100-110 kmph or so even after providing full throttle input. My friend promptly took it into VW Downtown and they accepted that there was a problem, most probably with the ECU.

They tinkered with it, got some codes from the company according to my friend, declared it fixed and gave the car back to him. I don't have details on what exactly was worked on- apparently they didn't give him a job card copy.

Now the car behaves in a rather strange manner- with a soft foot on the accelerator, the car in D mode goes steadily up to around 80-90 kmph with no problem. It has issues going beyond 100 kmph. My friend says that if the car is going on 80-90 kmph and he wants to increase the speed of the car, he has to push down much harder on the accelerator for it to go to 100 and beyond, often using kick down or tiptronic downshifts to 5 or even 4 to get the speed he wants (up to 140 kmph).

If he drives in manual (tiptronic) mode, car behaves fine till 5th gear but once 6th is engaged, the speed doesn’t increase as expected despite pushing the accelerator hard. He has to necessarily downshift to 5th to gather the required pickup.

The FE also has suffered as a result of this behavior of the AT.

Couple of additional factors:
- My friend is not a petrol head but has driven ATs before and says that this is not normal kick down behavior.
- Downtown VW service engineer/technician has tested the car twice and accepted that there is an issue…saying this is not normal.
- I myself have exactly this exact same spec car and have driven mine for 6 months/8000 km now and have never observed any such behavior- even with a light foot, on a clear stretch of road you can easily go up to 140 or so without having to downshift repeatedly.
- My friend swears the problem didn't exist before his sudden stop and visit to the shop.
- The car is a regular 6-speed Torque convertor-type AT and *not* a DSG.
- Downtown VW claim they have never seen this problem before in this car and say they have written to the company for a solution.
- Since the car is in Bangalore, I have not driven it myself.

I have asked my friend to get a second opinion at Bangalore Motors, since evilshantanu's experience suggests they are better at their job than Downtown. But have asked him to wait till I start this thread and get some expert opinions flowing in.

Any ideas what could have happened? And what's the solution?

Problem seems to be with gearbox. Our octy with DSG suffered same kind of problem. Once at high speed got a hit (small stone) beneath and it refused to go above 80 km/hr.
Dealership could not locate the problem and in third visit asked to change complete gearbox. I got it fixed by local garage in Baroda.
Get the gearbox thoroughly checked outside.

Maybe a transmission or an ecu reset may help? Tell him to put the car on, to the position just before the starter cranks, and press the accel down fully for 20 seconds at least. After that to just start the car and drive around.

Another option may be to disconnect the negative terminal of the battery for 15 mins so that the ecu resets.

A 3rd option possibly could be asking the VW people to reset it through VAG-COM.

Raosaheb, the Vento does not have a DSG (thankfully) and i do not suggest the owner to take the car to a roadside dealer, well at least not at first, especially keeping in mind it would be under warranty.
I think maybe the band setting of the gearshifts needs to be looked into. Make a noise at the dealership and threaten to write to VW if this is not sorted out asap. Maybe you should try giving it to some other VW dealer. You will be surprised with the amount of "Dense" people you may find employed in authorized dealerships. Ask to see the service manager and tell him to sort it out asap. Go for a drive with the guy to show him what the problem is. Also tell them that if they cant fix it you might consider going to a non authorized dealer at their cost and consequences and and without prejudice to the your warranty, as they are unable to fix the problem, whatever it is.

Slightly OT, Akshay, this is something that i did not knew. Just so that i understand this correctly, you are suggesting is switch on the ignition (So as all electrical like lights, ac fan blower are on, but the engine is still switched off) and then press the accelerator for 20 secs?

If my car is running fine, would it do any good if i decide to reset the ECU? Lately i have been feeling that the zip is slightly less than earlier. Is there a possibility that the ECU is now more tuned to run on fuel economy mode?

This is fantastic DIY ECU resetting technique to be honest. Thank you for that.

Oh nono. You misunderstood. It does not reset the ECU in 99% of the cars. But this will work only if the car has drive by wire (i.e electric throttle) or an automatic gearbox, and will reset either one or both of those. Again the procedure is different for different companies.

While hard-braking did your friend move the gear lever from D to D2 or D3 to get engine braking?

Exactly my argument!. I guess when there was that sudden kick down situation, the Auto box might have lost when and where there should be a kick down.

Btw, what controls the Auto Box?. Is it the ECU? Or does it have a stand alone controller?

:OT Even the Octavia did not have the DSG gearbox.

Bomi, there is no D2/D3 setting on the Vento AT box (it is a PRNDS sequence). He did not change gears, just stayed in D when he came to a sudden stop.

Thanks for info Anshuman. Skoda Surat dealer quoted 2.8 L to replace it.I got it repaired from Baroda for 18k and sold the car within a month. My partner have Laura DSG and once I heard strange klicking noise after a drive of 500 kms (while returning from Kolhapur). I stopped the car,put in N and again D and that noise disappeared.Reported this to Skoda dealership and they said its no big deal as DSG is very complicated system (some sort of mechatronic)
I think if anyone makes advanced complicated system,it must be reliable and robust also.

I think the problem may be with the fuel cut-off supply. I am saying this since a similar situation occurred with my friend's auto laura. He took it to the dealer and they reset the fuel supply by pressing a button. I am not sure that this is the problem, but it can be checked at the service centre.

In most newer cars there is a TCU - Transmission Control unit.

IMO noopster's friend should follow what Akshay and carfreak has to say.

Edit: Learnt that some cars have the ECU and TCU combined into one Powertrain Control Module.

http://en.wikipedia.org/wiki/Transmission_control_unit

Thanks guys. My pal has managed to talk to someone senior at VW and is directing his attention to the problem (and this thread!) Hope to find a solution quickly.

Quick update- VW have returned the car after pronouncing it repaired. They apparenty had to do a TU reset- what akshay was talking about- and the car now doesn't suffer from the acceleration problem anymore.

My friend is still not 100% convinced- he has been driving it and says it still doesn't match the performance in its early days, but since the VW folks are adamant that the problem is resolved and ONLY if it recurs will they consider the last resort: replacing the transmission completely (at their own cost), he is OK with it. That was the solution that Raosaheb and others had offered.

Thank you akshay and everyone else on this thread- as usual T-BHPians remain a step ahead of the market!

Mods- you may close this thread. Will request a resurrection of anything further develops- thanks!