Audi A6, 1.9tdi, 2001 - Low power, flat spots

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Tue 29 May 2018 15:28
Audi A6, 1.9tdi, 2001 - Low power, flat spots - Will Briggs

Hi all, in a bit of a bind !

My EGR was clogged with carbon so I removed it and my inlet manifold and cleaned them. Looks much better now but now it's all back together I have low power. I can hear the turbo so confident that's working yet I struggle to get to and stay at 70mph and also flat spots (more noticeable in 3rd at about 3,000 rpm)

I took it all apart again this morning, made sure everything was tight and done up properly and it's made no difference. I drove with the MAP disconnected and it made no difference - could this somehow be the issue?

The car ran worse with the MAF disconnected so I guess that's fine. The EGR does move freely when manually opening and closing and all hoses are connected. No splits from what I can see.

Does anyone have any ideas, or could give me a fresh insight, please? Any help will be greatly appreciated

Edit: Other than a bit of black smoke the car ran well before this

Edited by Will Briggs on 29/05/2018 at 15:35

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Tue 29 May 2018 17:05
Audi A6, 1.9tdi, 2001 - Low power, flat spots - hardway

Have you scanned it?

As for the MAP that'd be the manifold pressure sensor?

So no change when unplugged,

Best guess without access to live data from a scanner would be an inlet vaccum leak.

Check all the gasket/faces where you removed parts.

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Tue 29 May 2018 17:20
Audi A6, 1.9tdi, 2001 - Low power, flat spots - Will Briggs

Not scanned it yet, I've put the question out locally for someone with Vag Com otherwise I'll take it into a garage this week. I've double checked and there are no visible signs of any leaks. I'm guessing it's going to be something really small that I've stupidly missed.

Will update if I manage to find anymore info. Thanks for the response !

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Tue 29 May 2018 19:22
Audi A6, 1.9tdi, 2001 - Low power, flat spots - elekie&a/c doctor
Is it possible that you have fitted the maf sensor the wrong way round? There should be an arrow mark on the plastic to indicate air flow direction.
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Tue 29 May 2018 21:35
Audi A6, 1.9tdi, 2001 - Low power, flat spots - Will Briggs

I've had car plugged in and it's come up with P1556 - charge pressure control, negative deviation. A little research has shown me that it's either carbon in the actuator veins (the rod moves so hopefully that's fine) or a vacuum leak caused by a damaged hose. The hoses do look very work and one of them is split at the end - visually it's sealed but that could be it.

I'm going to replace all the hoses with silicon lines at the weekend and hope that resolves it

Any additional comments or advise are greatly appreciated - I'm a self taught maintenance from home person but this is new territory for me !

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Tue 29 May 2018 21:50
Audi A6, 1.9tdi, 2001 - Low power, flat spots - elekie&a/c doctor
I think you are on the right track here.Make sure all the vac hoses are good with positive connection to the vac lines.Also make sure that the vac pipes to the turbo actuator valve are on the correct way round .
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