TDI Power Loss

SJHE

Member
Hoping for some advice if possible.

My TDI seems to have lost its ‘go’ and although it still rattles along on the flat very well, any sort of incline kills the speed and it has little in the way of power in any gear.

My first assumption is that it’s a turbo related issue and I was therefore wondering if there is any particular order in which I should troubleshoot?

I have had a look at what I think is the anti shudder valve which is next up from the intercooler but I can move the valve easily by hand. There is some wet oil inside the hose (pictured). Is this normal?

I’ve circled where the hose connects to the valve body. This is held on by a sprung clip and although it’s tight to get on and off, the connectIon seems quite loose in that there is play up and down. Is this normal and would it likely cause an issue?

Also wondering if there is a quick way to work out whether it’s a 75 or 90 engine?

Any suggestions much appreciated.
 

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Car with 90 engine should have a red "i" on the tdi on boot

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tdi 90 also has a pressure switch on the metal air pipe that crosses the front of the engine up to the rubber pipe you have disconnected.
 
Thanks for that. I always thought it was a 90 but saw some photos on another site earlier showing both engine versions and mine looked more akin to the 75. Anyway, it has all disc brakes and the sensor on that pipe so she is a 90 as originally thought.

So turbo off for a thorough clean? Or would something like Forte turbo cleaner added to the fuel make any difference?

Thanks
 
I would run a chemical clean through the turbo to see if it is sticking vanes. Then have a VCDS scan done to see what boost the turbo is producing. Worth checking all the air pipes for holes and loose fittings, the condition of the intercooler and the little rubber hoses that run from the turbo.
 
Before doing anything add a whole bottle of redex diesel treatment and 200-400ml of 2 stroke oil in with a tank of fuel.

Ideally you want 2 stroke oil with the spec:

JASO FC ISO EGC API TC or the same spec but with "D"s instead of "C"s. Mix and match ds and Cs.

My uncles 1998 2.5 diesel A6 had a weird starting problem and then hunting idle that would happen multiple times a week. His very good audi independent garage couldnt fix it. When he came over to me I told him about it and we added as above before we went on a long drive. He said he noticed smoother running straight away and his starting/idle issue is gone.

My tdi runs a lot smoother with it. There's a lot of detergents in 2 stroke oil

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One bottle of Forte Turbo Cleaner later and a 50 mile motorway blast and it’s running like a dream again! The difference was noticeable within 15 miles and by the time I’d hit 35 miles, it was pretty much fixed. Full power now restored in all gears and pulling strongly with no smoke or hesitation. Appreciate everyone’s help and highly recommend trying this as a first port of call if your A2 is down on power before going to the trouble of pulling the turbo off for overhaul.
 
One bottle of Forte Turbo Cleaner later and a 50 mile motorway blast and it’s running like a dream again! The difference was noticeable within 15 miles and by the time I’d hit 35 miles, it was pretty much fixed. Full power now restored in all gears and pulling strongly with no smoke or hesitation. Appreciate everyone’s help and highly recommend trying this as a first port of call if your A2 is down on power before going to the trouble of pulling the turbo off for overhaul.
Congrats! Definitely add some 2 stroke oil too!

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Really glad that has produced the results expected. In the future you may want to think about the fuel you use, want to add an additive to the fuel or just wait until you need this more drastic treatment.
 
Congrats! Definitely add some 2 stroke oil too!

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Have to admit I’ve been adding 2 stroke oil for last couple of years to both our a2s ..As recommended to do so by one on here ?..I know it’s subjective but I for one think it’s a good idea ..
 
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