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Old 26th June 2017, 15:29   #1
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Default Solved: VW Polo GT TSI power drop after service! It was the air filter

The saga Of GT-TSI and air filters and misplaced vendor quality checks of Volkswagen India

To start off with, I bought my GT-TSI after going through each and every thread on this forum, on this phenomenal car. Thanks to TBHP members in keeping newbies like me fully enlightened.

Knowledge is power, community is empowering.

I am bowled by the performance of this machine in the city and on the highways. I needn’t say more as everything on this car has been discussed to absolute detail including mods, optimizations, performance enhancements, etc.

One line history: I bought a GT-TSI Carbon steel from Bangalore Palace Cross Mysore Road VW showroom sometime in June 2016.

The time was 1st service (with only 7500km but 1 year up), so I called them and asked for a pickup of the car. One thing I noticed is that, unlike Maruti Swift (My previous car Swift 1.3L petrol, the first edition) the service center actively does not keep track and call you before the due date. Anyway my car was picked up and delivered two days later. Everything seemed cool until I observed a few things.

1. The car was smoother. The suspension was smoother than before. While I preferred the hard suspension as it was before service. Well it makes for good city ride, but not a GT ride.

2. The Engine felt quite powerless. This was alarming for me. Although I’m not a ripper on the road, I could easily make out the reduced torque, and laid-back pickup.

I started feeling like I’m driving a naturally aspirated engine. The turbo kick-in was around 2.5 to 3K. There was no linear acceleration like how it was before. From 0-2.5K RPM there was sluggish acceleration and very less torque, glaringly experienced on inclined roads, and after that, a sudden torque surge, and rpm used to shoot up till 4K. To ensure I was right, I drove it for about 50 km. I asked a friend who had driven my car, and he had the same opinion too.

I called up VW palace cross, and explained it to them in detail. The reps told me that nothing is changed. Car is normal, ‘we didn’t see issue in diagnostics’. (argh.. human experience is better than software sometimes). So they sent across a person who is a customer interface technician.

He arrived on a Saturday, and we drove in the BLR Saturday traffic, to silk board, and then towards E-City flyover. While I could easily make out the difference in performance, the person said ‘sir everything is normal maybe it’s the petrol quality’. It’s a bit absurd, because when they sell the car, they claim homologation and that it works with Indian fuel. But, the service rep during service says, Indian fuel conditions are not good enough so you have to add additives. I gave him a piece of my mind. From the day I’ve bought the car, GT-TSI runs on only shell or shell V-Power. Although I get a bit better power/acceleration with V-Power, in normal conditions, shell standard petrol has been good enough, and I told him that.

While he wasn’t convinced on petrol quality, I wasn’t convinced on the performance drop. Eventually I booked another pickup.

They took the car, apparently did a ‘DSG software reinstall’ and sent it back two days later. Result.. no change. Still sluggish. Non-linear acceleration. For most of my driving, I haven’t felt a need to depress the accelerator pedal for more than 30% in the D-Mode. But now, the car in Sport mode was acting like D-mode. I knew something isn’t right.

Here comes the interesting part: I called up VW palace cross. I had long discussions with them, asked them if they updated ECU, what change was done to the DSG software, is there the dieselgate kind of fix for GT-petrol too? (why not.. because its VW, and they paid 14 billion for cheating and rigging ECUs). Obviously the answer was the same. “Sir, we only changed engine oil, replaced air filter according to specs, serviced the brakes, and checked diagnostics”.

“Sir we have some additives for your car, why don’t you try that. It improves octane, and ensures the injectors are cleaned”. I was like WTH. What kind of technicians are they (apparently German trained) to add additives to improve engine performance. I was quite enraged.

So the next Saturday my idea was to go to the workshop and ask for a GT that hasn’t been serviced yet, drive that and mine, and compare the performance. During the week, I couldn’t sleep well. This thing kept ringing in my mind. Anyway I dropped in on a Saturday early morning to the VW service center in Rajajinagar.

A rep was assigned to me. Mr.Nandish. I’m mentioning his name because he was very helpful. During our discussion, I realized that he was someone open to thoughts. His mindset was that, ‘nobody knows everything, We as reps have a POV, and customers will have another POV, there is much to learn’. Much appreciated. He was accepting of the ideas of other people and rationally evaluating based on evidence. Much similar to the Germans (with whom I work for my day-job).

Saturday : We set out on a test ride. He drove my car for about an hour. Said nothing is wrong. I had to explain to him the whole story once again. And then I asked him for a GT that is not 1st serviced yet. Luckily there was a GT for its 6-month checkup. So we took out the car. The moment I touched the accelerator pedal of the other GT, I knew this is it. This is what was missing. The torque, the power, the acceleration. This is GT. Mine isn’t behaving like that. So I asked him to drive. He too kind of realized that something is different. After driving this car around in different conditions, we then returned, and then took my car to the shop floor.

The shop floor was an interesting place. Totally and completely German equipment except for the coffee cups. There are very good processes in place. Every process goes through a checklist and in an orderly way.

My hunch was on the air filter. The part number on the factory air filter and post-service one was different. Moreover, the box of the air filter says 1.6 Diesel. When I asked about the mismatch, they checked on their internal software (apparently) and said “Company continuously keeps changing filter spec, and this is the relevant part number, there is no mismatch”. I am aghast. German concepts are simple yet complex. They do not change things radically. And if anything changes, it will have relevance over the previous one. For instance, if the part number is 6RO-129-620-A , the upgraded part number could be 6RO-129-620-B and not a radical change to a completely new numbering structure 6RF-129-620. This is because the format of the part number is based on location_of_the_part-enginetype etc. So unless engine type and location of the part changes, there will be only incremental upgrades.

Solved: VW Polo GT TSI power drop after service! It was the air filter-part_info.jpg

http://www.aircooled.net/vw-part-numbers-explained/

http://www.myturbodiesel.com/wiki/vw...ained-in-etka/

https://shopdap.com/volkswagen-audi-...-how-it-works/

The structure of the air filter has 2 layers. Inner layer consists of a corrugated paper type with an outer layer of fiber to trap particles.

The factory fitted air filter in the car was made by UFI with part number: 6RO-129-620-A made in Tunisia. Costs 18-26$ approx across the world.

Name:  UFI.jpg
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The one installed in the car was an air filter made by Lumax with part number 6RF129620 Made in India (Pune). Costs 396/- Pre GST inclusive of VAT. As on mid June 2017

Solved: VW Polo GT TSI power drop after service! It was the air filter-lumax1.jpg

More pictures of the Lumax air filter in this thread: http://www.team-bhp.com/forum/diy-do...-cleaning.html (DIY: Volkswagen Vento TDi - Air Filter Cleaning)

Above are the pictures of both. The UFI and Lumax. What I observed is that the quality of the two air filters was very different. The UFI was of much better quality than the Lumax. The mould quality of the Lumax is crap. The injection moulding remnants, the overly thick outer fibre.

Solved: VW Polo GT TSI power drop after service! It was the air filter-lumax2.jpg

It looks much worse than a local air filter available in places in SP Road. I’ve seen Maruti Air filters. They are of far better quality than this one. This is just plain substandard.

Check out the thickness of the fibre layering on the outer surface. Its common sense, that the thicker the filter, the less the air that gets in. The design of air filter is a thin line of art. One has to get most particulate matter filtered without hampering the density of air. Its like a skirt design, shouldn't be too high nor too low which will mar the intent.

Since my car had done 7.5K, there was 7.5K life left in the UFI filter. So I asked him to revert to UFI filter. He got the UFI filter blowed, to remove black soot particles, removed the Lumax and installed UFI, ran diagnostics, updated some Software (apparently he said).

Then, once the car was on the road, it was back to normal. It felt like a GT. The guy grinned. “howdu sir, power jasti ide!” (yes sir, power is more … in Kannada). We drove for a long distance. Everything now felt normal. We ripped, crawled, snailed, went on inclines. All perfect. Car had very linear acceleration now. And adequate torque generation at the right rpm. And yes, like always ,throttle was depressed not more than 30%.

The car was back on the shop floor. He ran another diagnostics. Things were normal. And then I showed him, that hindrance in airflow will make your intelligent ECU realize reduced air and oxygen, which results in less fuel injection, leading to lowered power. While I’m not an automobile engineer, this was plain common sense. Later I had a chat with the head of the service centre. Explained him the problem and he made a note of the part number. I will be writing a formal email complaint to the service head soon. The following are some things I realized out of this experience:

1. The Vendor (Lumax makes crap air filters for VW) doesn't know how they got through the apparently claimed German standard quality check

2. Cost of filter is 396/-. For someone buying a GT, even 800/- per air filter is ok, but not substandard quality

3. Surprised that the same airfilter is used for petrol and diesel.

4. The same air filter is used in the Vento diesel and Vento 1.6. Since the torque in those cars is more, the little reduction in airflow will result in marginal reduction in power, sometimes which can go unnoticed. But surely an analysis of Mass Air flow should throw up the issues on the result sheets

5. They have the assumption that whatever spares that arrive from the company are perfect fit. “sir Volkswagen has approved. They will have done all testing”

6. Glad to have met some service reps who are accepting of the fact on a customer's opinion. Initially they thought that customer is throwing in jargon, but later when they realized that I was armed with technical knowledge (gained in this forum), they started to listen.

For me, the first point of doubt was when there was a mismatch of part numbers. Now my next question is how do I trust VW to provide authentic spares. And if they don’t, where can I start importing them from Europe. I’d be glad if the stalwarts in this forum can help me with that. :- )

Thank you much for giving me a platform to share thoughts here!

Last edited by GTO : 27th June 2017 at 16:41. Reason: Spacing :). Thanks for sharing!
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Old 26th June 2017, 17:32   #2
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Default Re: Volkswagen Polo 1.2L GT TSI : Official Review

Thanks for the info. Will keep this in mind when I give my car for the 1st year service. Good that your issue is finally solved.

Quote:
Originally Posted by avanishphatak View Post
And then I asked him a GT that is not 1st serviced yet. Luckily there was a GT for 6-month checkup. So we took out the car.
Would you be kind enough let me know more details of this car that you test drove.
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Old 26th June 2017, 18:22   #3
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Default Re: Volkswagen Polo 1.2L GT TSI : Official Review

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Originally Posted by hemanth.anand View Post
Would you be kind enough let me know more details of this car that you test drove.
Well, I don't remember the exact details but it was a carbon steel TSI.
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Old 26th June 2017, 21:20   #4
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Default Re: Volkswagen Polo 1.2L GT TSI : Official Review

Quote:
Originally Posted by avanishphatak View Post
The saga Of GT-TSI and air filters and misplaced vendor quality checks of Volkswagen India

For me, the first point of doubt was when there was mismatch of part number. Now my next question is how do I trust VW to provide authentic spares. And if they don’t where can I start importing them from Europe. I’d be glad if the stalwarts in this forum can help me with that. :- )

Thank you much for giving me a platform to share thoughts here!
I am glad that you are now a happy customer. But as you figured out the issue it may not be the same case for others. You should write to the higher management of VW.

Everyone doesn't check the brand of AirFilter used after every service.

Last edited by GTO : 28th June 2017 at 10:08. Reason: Typo
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Old 26th June 2017, 23:06   #5
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Default Re: Volkswagen Polo 1.2L GT TSI : Official Review

Quote:
Originally Posted by avanishphatak View Post
My hunch was on the air filter. The part number on the factory air filter and post-service one was different. Moreover, the box of the air filter says 1.6 Diesel. When I ask about the mismatch, they checked on their internal software(apparently) and said “Company continuously keeps changing filter spec, and this is the relevant part number, there is no mismatch”. I am aghast. German concepts are simple yet complex. They donot change things radically. And if anything changes, it will have relevance over the previous one. For instance, if the part number is 6RO-129-620-A , the upgraded part number could be 6RO-129-620-B and not a radical chance to a completely new numbering structure 6RF-129-620. This is because the format of the part number is based on location_of_the_part-enginetype etc. So unless engine type and location of the part changes, there will be only incremental upgrades.

...

The factory fitted air filter in the car was made by UFI with part number: 6RO-129-620-A made in Tunisia. Costs 18-26$ approx across the world.

...

The one installed in the car was an air filter made by Lumax with part number 6RF129620 Made in India (Pune). Costs 396/- Pre GST inclusive of VAT. As on mid June 2017
This was really informative about the air filter. I really appreciate the details you have provided.

I felt like mentioning that differences, like 6RF from 6R0 in the part numbers, indicate the localized part (the former) and the globally available part (the latter). For most part, parts with 6RF in the part number are manufactured in India (for example, the air filter by Lumax), while sometimes they are manufactured out of India, but primarily meant for the Indian cars (for example, BCM manufactured by Continental in Europe, for Indian market, with its part number having 6RF in it).

Moreover, sometimes part numbers such as XXX XXX XXX A/B/C indicate part revisions, while other times A/B/C can refer to completely different types of parts like shock absorbers for normal suspension, or for sport suspension.

I started discovering this when the localized shock dampers were installed in my car, that had European dampers factory installed. Had they checked for VIN specific parts, this fiasco could have been avoided.

These Germans are complex cars, with two cars manufactured one after the other, still having different parts, even if the cars are of the same trim.
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Old 27th June 2017, 01:15   #6
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Default Re: Volkswagen Polo 1.2L GT TSI : Official Review

Quote:
Originally Posted by avanishphatak View Post
The saga Of GT-TSI and air filters and misplaced vendor quality checks of Volkswagen India
Invaluable post really. I am curious to know if the newly manufactured GTs come with UFI or Lumax air filter out of the factory.
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Old 27th June 2017, 08:11   #7
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Default Re: Volkswagen Polo 1.2L GT TSI : Official Review

Quote:
Originally Posted by avanishphatak View Post
The saga Of GT-TSI and air filters and misplaced vendor quality checks of Volkswagen India

For me, the first point of doubt was when there was mismatch of part number. Now my next question is how do I trust VW to provide authentic spares. And if they don’t where can I start importing them from Europe. I’d be glad if the stalwarts in this forum can help me with that. :- )

Thank you much for giving me a platform to share thoughts here!
I have had the same feeling on my car as well. The linear torque from say 1700 to 4+ K was missing after the 7500/1 year service. The car now responds with aggression only in the 3K-5K and it takes a good 2-3 seconds to wake up to those revs from say, 2K.

I would have my filters checked as well. Thanks for this.
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Old 27th June 2017, 12:23   #8
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Default Re: Volkswagen Polo 1.2L GT TSI : Official Review

Very interesting find avanishphatak!

I've moved your posts to a new thread so it can help others who might be searching for a solution to the same problem.

It's incredibly frustrating to pay 10 lakhs for a car, and then have it act like a shadow of itself after a service.

As it is, there's a majorly negative sentiment about the dieselgate fix VW is applying: (link)
Solved: VW Polo GT TSI power drop after service! It was the air filter-screenshot-20170627122755.png

Quote:
Originally Posted by swissknife View Post
I have had the same feeling on my car as well. The linear torque from say 1700 to 4+ K was missing after the 7500/1 year service.
Do switch back to the OEM filter and let us know if it makes a difference.

That way we can be sure that it is 100% the filter that is causing this, and not some other variable (eg. "software update" that avanishphatak mentioned).

Last edited by Rehaan : 27th June 2017 at 12:31.
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Old 27th June 2017, 13:53   #9
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Default re: Solved: VW Polo GT TSI power drop after service! It was the air filter

Mine is a 2014 Nov bought 1.6TDI

I just checked through my invoices and for the service in 2015 Nov and 2016 Nov they have used the 6RF filters.
So it seems only that is available now. What does one do when you have to change filters?
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Old 27th June 2017, 14:01   #10
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Default re: Solved: VW Polo GT TSI power drop after service! It was the air filter

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Originally Posted by Mohan Mathew A View Post
Mine is a 2014 Nov bought 1.6TDI

I just checked through my invoices and for the service in 2015 Nov and 2016 Nov they have used the 6RF filters.
So it seems only that is available now. What does one do when you have to change filters?
I also checked the invoices of my car, and they have put in the Lumax India air filter during the last service.

I will have them order the UFI one, if that is not in stock, on the next service. My car, being a 2010 Vento 1.6 TDI, would most likely have that listed, if we look up the part number based on my car's VIN.
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Old 27th June 2017, 14:34   #11
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Post Re: Volkswagen Polo 1.2L GT TSI : Official Review

Quote:
Originally Posted by Rehaan View Post
Do switch back to the OEM filter and let us know if it makes a difference.

That way we can be sure that it is 100% the filter that is causing this, and not some other variable (eg. "software update" that avanishphatak mentioned).
I checked my invoice and they have replaced the part to - 6RF129620. Have asked if they still have the old part to replace and check. Hopefully they haven't dumped it in the garbage. Since my car has done about 7+K KM, it should still have life.

Got to figure how I can get hold of the correct part, fix and check.

Extract from my invoice:
Solved: VW Polo GT TSI power drop after service! It was the air filter-vw-air-filter.jpg

Last edited by Rehaan : 27th June 2017 at 15:26. Reason: Fixing image insertion
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Old 27th June 2017, 15:08   #12
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Default re: Solved: VW Polo GT TSI power drop after service! It was the air filter

Thanks for this useful post. I have observed the same issue in my Skoda Rapid DSG, the DSG moves to higher gears quickly due to lack of air flow, I believe. I had to get the air filter cleaned to fix the issue. And the addition of flow restrictor to the 1.5 TDI engines has worsened the problem. I am getting the air filter cleaned every 2 months as a remedy.
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Old 27th June 2017, 18:07   #13
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Default Re: Solved: VW Polo GT TSI power drop after service! It was the air filter

Thank you for the very informative post.
I own a 2014 Vento 1.6 TDI and off late I've been noticing that the car does not feel as powerful as it used to. It sometimes struggles in pulling from a dead stop in second gear with just me in the car whereas, earlier it used to be easily able to pull with a few people and luggage in it. Since the car has done over 40K kilometers, I attributed it to the car getting older and convinced myself that nothing can be done about it. Taking it to the service folks would have been a complete waste of time as you have described in your post so I didn't bother. I would have to check my last service (April 2017) invoice for the exact part number for the air filter but just from the looks of it, I think I have the same one.
I doubt if it would be possible to source the UFI filter easily but how about K&N filters? They sure are expensive but apparently, they last 50K miles (or 50K kilometers considering Indian conditions).
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Old 27th June 2017, 19:40   #14
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Default Re: Solved: VW Polo GT TSI power drop after service! It was the air filter

Hi @avanishphatak, very interesting and informative, thanks for sharing!

However, I'm really uncomfortable with the fact that they allowed you to Test drive another customer's Polo. This is simply not done, though I know that sometimes, that's the only way to troubleshoot some issues. Sorry if this is OT. Mods, please remove this if inappropriate.
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Old 27th June 2017, 20:30   #15
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Default Re: Solved: VW Polo GT TSI power drop after service! It was the air filter

Great analysis and thank you for documenting.

Went back and checked the service history of my Vento TSI and found that right from the first service, the part number of the replaced air filter is that of the locally made one that apparently has issues (made by Lumax with part number 6RF129620 Made in India (Pune)).

So looks like this is the part that has been used at least since 2013. Personally don't know what was the one the car came with and it is too far back to recall if there was a performance difference after first service. Would be good if someone who recently did a service comment about any performance changes observed.

Last edited by Rajeevraj : 27th June 2017 at 20:31.
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