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Skoda Octavia VRS - Very bad jerks on sudden acceleration


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#1 crdhanak

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Posted 19 April 2010 - 17:07

Hi Guys,
I have a Skoda Octavia I - VRS (2005). The mods I have are Custom Code Phase 1 remap, K&N Typhoon, Forge DV 007, Remus exhaust.

For the last couple of months I have a nasty problem that the Skoda guys have not been able to resolve. In any gear, when I press the accelerator HARD, the car jerks several times and gives off a kind of sputtering sound. If I keep the accelerator pushed down then after a few seconds of jerks the car gets the normal acceleration. Alternatively if I ease off the accelerator the jerking stops and then when I slowly press the pedal the car seems fine.

It is only on sudden hard acceleration that the car jerks very badly so I do not have any problem in city traffic. But only when I am pushing the car hard or overtaking that I face this problem.

I have checked the site forums, but have not found any identical problems. What I am experiencing is different from the famous hesitation in remapped cars.

Can anyone suggest what could be the cause?

Thanks
Chintan

#2 chicken_eyebrow

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Posted 20 April 2010 - 08:06

Dirty or knackered throttle body, dirty or blocked fuel filter or injectors, or a broken or leaking vaccuum pipe or boost hose.

If you can fault code scan it it might have a stored code which will point you in the right direction

#3 Bodge

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Posted 20 April 2010 - 08:57

Did it do it before the CC stage 1 map?

Do you know what Skoda tried? Do you have any fault codes?

Probably 90% of running issues come from leaking vacuum/breather/boost hoses and dirty throttle bodies.

#4 Flybikeslee

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Posted 20 April 2010 - 09:55

you played with your fuel pump at all?

#5 crdhanak

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Posted 20 April 2010 - 17:50

You guys are amazing. It indeed seems to be the boost hose which is the problem. The rubber has become very soft due to age and heat. It seems that on sudden acceleration and the demand for sudden more air, the rubber is folding on itself causing insufficient air into the engine causing the problem. Atleast thats what I think is the problem. It even has a small a crack in it. Unfortunately will get the replacement part only by the end of the week. But fingers crossed, it should solve the problem.

Thanks a ton!!!

God bless Briskoda experts!!

Chintan

#6 vRSLen

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Posted 20 April 2010 - 17:55

Result then :)

#7 crdhanak

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Posted 01 May 2010 - 17:03

Hi, changed the breather hose and other pipes along with it. Unfortunately the problem still persists.

They were in a really bad condition so I was very confident that this would be the cause. Unfortunately not so.

What else should I check? The fault code described that it is getting insufficient air volume. I do not have the fault code number though.

BTW how do I post a pic with this post?

Regards
Chintan

#8 David 8

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Posted 01 May 2010 - 21:20

The fault code described that it is getting insufficient air volume. I do not have the fault code number though.

BTW how do I post a pic with this post?

Regards
Chintan


Could that code be for the MAF ??



Use photo bucket and link it



HTH

#9 crdhanak

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Posted 11 June 2010 - 18:04

Hi,
FINALLY!!! The problem got solved. It turned out to be a combination of various things. The following is the sequence of actions taken over the last 45 days (mainly as Skoda did not have parts)

The problem was that the car was jerking like hell on acceleration. It would happen in any gear but typically between the 3000 and 5000 rpm. There were no consistent error codes found.

Based on the inputs from this forum I had the car checked for the damage to the breather hose and this was found to be cracked. Replaced it.
While replacing the breather hose, the vacuum pipes were found to have hardened and were very brittle. They broke while the breather hose was being replaced. So replaced the vacuum pipes.
Unfortunately the problem did not go away.

Replaced the spark plugs - it was time to change anyway. But problem not solved.

Had the Throttle Body cleaned and aligned. Problem still not solved..

Disconnected the MAF as suggested and found the car was jerking less. Tried using the MAF from another VRS, again it was jerking less but the problem did not get completely rectified.

Cleaned and reoiled the Air Filter

On a gut feeling asked the service center guys to check the fuel filter - Horror!!!! The fuel coming out of the Fuel Filter was BLACK!!!!
Changed the Fuel Filter and had the Petrol Tank cleaned. Black Sludge was found at the bottom.
It seems that at some point I got a very very very bad quality of petrol.
Put fresh fuel into the tank...unfortunately the problem still remained - no change.

Changed the MAF to a new one and suddenly the problem seemed to have reduced substantially.
Finally replaced the Fuel Filter from another VRS and ......SOLVED!!! Bought a few Fuel Filter immediately.

So it seems the problem was a combination of
1) Leaking Breather Hose - Though why this did not give a error code is beyond me
2) Cracks in Vaccum tubes - again why no error codes
3) Very Poor Quality petrol causing the fuel filter to choke up and collapse and the fuel pump to fail (again why no error codes - perhaps the fuel filter was working but was partially choked with sludge)
4) MAF was probably also dying a slow death and only compounded the problem.
5) The main problem I think is that there is no alternate to authorized Skoda service center in India, and since VRS accounts for less than 1% of Skoda sales in India, the authorized service center do not have highly trained and experienced guys for the VRS. It took the guys several months to finally identify and solve the problem.

But now my VRS is back and I am in love all over again!!!

Thanks a ton for all your suggestions. I hope nobody faces this problem.

Regards
Chintan

#10 chicken_eyebrow

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Posted 11 June 2010 - 20:07

Thanks for the detailed reply Chintan, this sounds like a problem not many people have had on here so hopefully this thread will give people something else to check out if they have a similiar problem. I reckon the black sludge and caked up fuel filter was 90% of the problem in your case but as those other hoses were on their way out anyway it was probably wisest to replace them.

Edited by chicken_eyebrow, 11 June 2010 - 20:08.