Erratic idling and misfire

[Ifty1]

Hi

I have a 2004 audi 1.8t quattro but am having problems with the engine light which keeps coming on.

Based on the VAG Com it first threw up the lambarda sensor which I changed then it gave me codes which related to Coils 1 and 2 which i also replaced.

Now I am getting the code 17705 - 'pressure drop between turbo and throttle valve p1297 upper limit reached'

I then cleaned out the throttle body but still have the same issue. The car idles a little rough and it seems to be drinking alot of fuel. I have also changed the coolant temp sensor and spark plugs.

I also checked the MAF sensor by unplugging it but it still idles rough so I dont think this is causing the problem. The previous owner had already replaced the diverter valve and I had a local mechanic check for air leaks via a smoke test but there were no signs of a visible leak

Can anyone help?

http://www.vwaudiforum.co.uk/forum/applied/misc/progress.gif

[5up3rman]

this could be cause by a few possible things:

leak from hoses, split or cracked pipe

fault boost pressure valve

diverter valve faulty or

dirty throttle body

since you cleand throttle then maybe start lookign at the hoses/pipes for any signs of splits or cracks.

someone else i'm sure can twell you how to check pressure boost valve.

[Ifty1]

Thanks for your help

I shall chaeck all the pipes again and have someone check the booster valve

I will let you know if this solves the porblem

cheers

[Dark Horse]

Had the same problem myself a few months back, turned out to be a collapsed disc inside the breather valve and throttle body that needed cleaning. See my thread here (http://www.vwaudiforum.co.uk/forum/showthread.php?t=100680)

[Ifty1]

Thanks mate. really appreciate the help. :beerchug:

After reading your thread I am going change the breather valve. I have already cleaned the TB, changed coils and temp sensor so will try this next

Will let you know if this solves the problem

[Ifty1]

I changed the breather valve and this instantly resolved the idling issue.

I did ask the Audi specialist that it might be the breather valve and he dismissed the idea saying that the breather valves are very reliable but as I knew you had the same problem I went ahead and changed the valve.

You were spot on Dark Horse, the disc inside the valve had collapsed. Now I just need to take the engine light off with a VAG com and hope nothing else comes up

Thanks for your help. You saved me alot of headache, time and money