TFSI hesitation/missfires at high rpm's

[jon-tfsi]

It is the injectors, mate my car did the exact same thing your describing. Bucking from 4k rpm onwards regardless of gear, i then installed pump and car would run to 5k rpm then just start dying. With absolutely no codes unless it threw me into limp mode. Give APD a call.

Yep this is also a possible cause. Its very difficult to be 100% sure the injectors are at fault until they have been swapped and this is a very costly thing to do. £400 for injectors and minimum 3 hours labour.
If it were injectors there would almost certainly be some misfires showing up on VagCom and there are NONE, which SUGGESTS that its not injectors. It doesnt mean its NOT injectors tho.

All your suggestions are greatly appreciated by the way !!!!!
I still want to get this sorted but Im just getting really tired of it now
Its probably something simple, its just a case of finding it.

 

[acespizee]

Yep this is also a possible cause. Its very difficult to be 100% sure the injectors are at fault until they have been swapped and this is a very costly thing to do. £400 for injectors and minimum 3 hours labour.
If it were injectors there would almost certainly be some misfires showing up on VagCom and there are NONE, which SUGGESTS that its not injectors. It doesnt mean its NOT injectors tho.

All your suggestions are greatly appreciated by the way !!!!!
I still want to get this sorted but Im just getting really tired of it now
Its probably something simple, its just a case of finding it.

The cost of getting the injectors looked at and changed were the reasons why i battled with Seat to get it done under warranty. Before they did this they changed: hpfp, fuel pump in boot, low pressure sensor, cam follower, pcv, etc. My problem only dissapeared when they changed injectors.

My car was completely fine in stock mode but as soon as i turned the software back on it would go all wrong.

My problem started the day i went stage 2, and what became obvious was that while the injectors were just about working well enough for stock they were obviously so crapped out that asking anymore would result in these mis-fire type hiccups at anything over 4K rpm.

Do you still have warranty?

 

[jon-tfsi]

My problem started the day i went stage 2, and what became obvious was that while the injectors were just about working well enough for stock they were obviously so crapped out that asking anymore would result in these mis-fire type hiccups at anything over 4K rpm.

Do you still have warranty?

Unfortunately the warranty has ran out.
My car also runs fine on standard software and only hesitates with software on.
Just rang APD and they remembered your car well loi....
They said your car ran very lean towards the top end and on VagCom advanced measuring blocks there were lots of misfires showing up. This is how they were sure ity was injectors.
Mine starts to get rich towards the top end, and no misfires are being counted on VagCom. This suggests its not the injectors.
Same symptoms, different cause

 

[zyklon]

I do have the car as collateral but in Seat here in Spain will not find anything, because the stock car has no problems.

I know another Leon Cupra TFSI misfires with them, both with other electronic revo. It seems that the problem is not with electronic, but do not dismiss anything.

Enriching fuel with revo SPS improvement but still failing.

 

[acespizee]

Sorry to hear that man, I hope you find your problem soon as this is the most annoying problem i've ever come across and it made me feel like dying.LoL.

Trust me i feel your pain.

 

[-pseudonymous-]

There appears to be alot of fueling/missfiring problems with the 2.0 TFSI engines, typically with the Mk5 golfs. I have the same fault code as Zyklon which appeared after logging my MAF yesterday, at around 6000rpm the power died off momentarily then picked up agen as you can see from my logs below. I think i may try logging the fuel pressure later to see if anything is a miss there.

 

[jon-tfsi]

OK the car has been in to another specialist and a few conclusions have been drawn.
We now think it could be the oil consumption causing problems.

The car is hesitating but not recording any misfires, so Andy, the Technician inspecting the car thinks its the ECU picking up "knock" and pulling the fuel and boost back slightly to preserve the engine.

The car uses a lot of oil. Approx 3 litres in the last 10K.
It doesnt breath heavily and I have never seen smoke come out the exhaust once.

The theory now is that the oil is getting past the pistons, affecting the combustion process and causing "knock", an uncontrolled burn of the air-fuel mix.

If this theory is correct the only remedy is a bottom end rebuild

 

[robdf2]

if oil is getting past your pistons then oil will be present as burnt oil from your exhaust.

 

[jon-tfsi]

Yes the burnt oil will exit the exhaust. The exhaust tailpipe gets very black also.

 

[robdf2]

but surely a compression test will tell you if it is or not?

 

[jon-tfsi]

I thought the oil was getting throught the PCV system at first and into the cylinders throught the intake manifold. A temporary PCV block-off was set up and all gasses / oil vapours exiting the PCV were routed to a lucozade bottle. after a few miles of hard driving there was no significant amount of oil in the pipes/ bottle just a few specs.

The intake valves were inspected with an endoscope camera which was interesing to see. They were suprisingly clean for a 60K tfsi.

Also if the oil was passing the turbo seal or valve stems, smoke from the exhaust system would be more apparent. We are assuming its passing the pistons at the moment

 

[jon-tfsi]

but surely a compression test will tell you if it is or not?

A compression test was done and the results were between 135-140 psi. This meant nothing to me at the time but was assured that it was ok.
Since then i have learned that they should be 160-200 psi on a new tfsi engine.
Also if they dont open the throttle plate whilst doing the test it can give lower readings. As the test took 20 mins by a local non-specialist garrage i dont think they will have done this.

The compression test should really be done again but it could be the scraper rings not removing the oil from the cylinder wall. If this is the case and the piston rings are ok the compression test could give normal readings but the oil could still be getting past the pistons.

 

[antoniscupra]

A compression test was done and the results were between 135-140 psi. This meant nothing to me at the time but was assured that it was ok.
Since then i have learned that they should be 160-200 psi on a new tfsi engine.
Also if they dont open the throttle plate whilst doing the test it can give lower readings. As the test took 20 mins by a local non-specialist garrage i dont think they will have done this.

The compression test should really be done again but it could be the scraper rings not removing the oil from the cylinder wall. If this is the case and the piston rings are ok the compression test could give normal readings but the oil could still be getting past the pistons.

Did you fing any solutions for the misfires?
I have the same problem.

 

[zyklon]

Hello. I solved the problem by changing valve springs. I know 2 other cases but it also managed to change the valve springs.
Suerte.

 

[antoniscupra]

Hello. I solved the problem by changing valve springs. I know 2 other cases but it also managed to change the valve springs.
Suerte.

Where are these valve springs?

 

[robdf2]

i had a whole replacement cylinder head , not just new springs guessing mine were pretty bad.

 

[antoniscupra]

i had a whole replacement cylinder head , not just new springs guessing mine were pretty bad.

Did yoy have missfires without any modification in your car?do you remember the fault that vag com shown?

 

[robdf2]

I had no VAG COM faults , the engine was very ticky and tappy and the exhaust sounded like it was blowing on tick over and when i changed gear you could hear a slight backfire.

The exhaust was changed first then all other parts eg MAF , PLUGS , INJECTORS but nothing fixed it , they had my car for 14 weeks and in the end did a compression test and found cylinder 3 was very high and i had a new head fitted bearing in my my car had only done 4,000 miles

To fault find and diagnose this problem is not easy, but 14 weeks was taing the pi$$.

Good luck mate.

 

[antoniscupra]

I had no VAG COM faults , the engine was very ticky and tappy and the exhaust sounded like it was blowing on tick over and when i changed gear you could hear a slight backfire.

The exhaust was changed first then all other parts eg MAF , PLUGS , INJECTORS but nothing fixed it , they had my car for 14 weeks and in the end did a compression test and found cylinder 3 was very high and i had a new head fitted bearing in my my car had only done 4,000 miles

To fault find and diagnose this problem is not easy, but 14 weeks was taing the pi$$.

Good luck mate.

Thank you my friend.

 

[antoniscupra]

Hello. I solved the problem by changing valve springs. I know 2 other cases but it also managed to change the valve springs.
Suerte.

Do you know the code of the parts that you use?i mean about spring valves.