Advice on acceleration hesitation on 1.5TFSI COD Manual?

[BarryM]

After a few years away I am back in the four rings! Purchased a 67 plate A3 1.5 TFSI COD manual Black Edition. The car has only covered 30k miles and has not done much over the last few years.

I have noticed the acceleration is hesitating when at around 4k rpm and seems to be holding back the power a little. The car runs fine apart from this. I have just had a full service, new spark plugs, injector cleaner and using the higher ron fuel (tesco 99). I have done a few hundred miles, emptied the tank with the injector cleaner and gave it a good blast. I have plugged the car into my friends Autel diagnostic computer and it's not throwing any codes up. I have also been in touch with Audi to see if there are any software updates available which they checked and there aren't.

Has anyone had this issue or have any ideas, I have done a few searches and its coming up with loads of possibilities? Thought I would try on here before taking it to a VAG specialist.

 

[northpole]

My money is on carbon buildup... since it's doing it at a higher rpm range.... you might want to consider a booking the car in for a carbon cleaning service.

 

[BarryM]

My money is on carbon buildup... since it's doing it at a higher rpm range.... you might want to consider a booking the car in for a carbon cleaning service.

I thought about this hence using the injector cleaner but wouldn't of thought It would be that bad at only 30k miles, but suppose short journeys wont of helped it.

 

[northpole]

Short journeys are the worst for carbon to build up quickly. The problem is direct injection into the cylinders, so the head and valves never get clean with an injector cleaner

 

[BarryM]

Short journeys are the worst for carbon to build up quickly. The problem is direct injection into the cylinders, so the head and valves never get clean with an injector cleaner

Thanks for the advice. I will get it booked in this week see if that sorts it, hopefully just the mobile carbon clean will do it, not the heavier walnut blasting!

 

[northpole]

You could go for the terraclean option they have a few different options that will sort it out, but you pay accordingly for those different options. But compared to the cheaper mobile carbon cleaning services, a terraclean wins every time. I think it's their special blend of carbon desolvers that does the trick. Whereas the mobile carbon services mostly use steam, granted it dislodges it, and moves it, but that just moves the lot downstream into the exhaust. The engine will be clean, but the exhaust? Not to sure about that, but i can be wrong.. I haven't utilised the steam option yet.

 

[BarryM]

You could go for the terraclean option they have a few different options that will sort it out, but you pay accordingly for those different options. But compared to the cheaper mobile carbon cleaning services, a terraclean wins every time. I think it's their special blend of carbon desolvers that does the trick. Whereas the mobile carbon services mostly use steam, granted it dislodges it, and moves it, but that just moves the lot downstream into the exhaust. The engine will be clean, but the exhaust? Not to sure about that, but i can be wrong.. I haven't utilised the steam option yet.

Been doing a bit of research and noticed the gas option doesn't work that well, may have to go down the walnut blasting route which is an inlet manifold off job, Il have a look at the terraclean though. I once done Il add to this and let people know the results , cheers pal.

 

[BarryM]

A little update with this issue.

I taken the intake pipe off and inspected the inlet ports through the inlet manifold with a borescope. They looked ok to be honest, a small amount on the valves but nothing excessive and the valve seats looked good.

I then replaced the PCV breather unit and a new set of coil packs which didn't make a difference. I have also tried another MAP sensor which did not work.

I am booked in a VAG specialist now for diagnostics as the issue is getting beyond me. I do have a small amount of play in the wastegate connecting rod, which I hear is common, would it be worth trying a set of the retaining clips first before going in as they are only a couple of quid and having a google says it can cause boost hesitation?

 

[BarryM]

UPDATE... I booked the car in with a recommended local VAG specialist near me which apparently has dealer level diagnostics and computers etc. After him having the car for diagnostics he said the car was misfiring on all 4 cylinders. Told him the parts that had been replaced since. He asked if It had had a replacement timing belt fitted to which it has not.

He then recommended me to replace the Solenoid valve'04E906423C' which is the cam adjuster magnet on the side and also the one on the top of the rocker part number '04E906455AC' as these can get clogged up with poor servicing and affect the performance/timing which made sense.

I replaced these parts and the car is still doing it. After speaking to him again he was adamant that it was a timing issue and the only other one it could be was a 'Oil control valve' part number '427003710' which according to him sits at the end of the cam where the cam magnet pushes onto. It comes with 2 holes to screw on with a special tool. Does anyone know if this can be replaced without replacing the timing belt?

The cost is adding up and I can't afford to keep guessing. I don't mind paying the money as long as it fixes the issue as I love the car and intend to keep hold of it.

I am in the North West 'Widnes', I don't mind travelling within reason, can anyone recommend a good technical specialist who can help or fix this issue? Cheers folks