1996 a4 tdi loss of power. help please

[marty67]

I have recently purchased an Audi A4 1.9 tdi which I am having a recurring problem with. Under certain conditions i.e. 60mph in 3rd, 70mph in 4th, and around 80mph in 5th, the car loses power and goes into what I can only describe as limp mode, (very poor acceleration in ALL gears). However when i briefly turn the engine off and the back on again, all power is restored untill I reach these speeds again. If I gently ease the speed up and change gear early I can build up speed but when I "floor it" I lose all the power again. There is no sign of any smoke when this occurs. I have changed the MAF sensor and all breather pipes for new ones and the fault still occurs. I also found that the piston inside the exhaust return was solid, but after freeing it the problem is still there. I have used VAG COM free version and the code is 00575 inlet manifold pressure - difference intermittent. I have also taken block readings when the car is idling, but don't really know what they are all about. Any assistance would be GREATLY appreciated. p.s. I live in Falkirk.

[marty67]

I've also changed the rocker head gasket bacuase this had a slight leak, but I don' think that this is in any way connected.

[ad4pm]

I had a similar problem with my '97 TDI, and fortunately it was under a warranty from a used car dealer, has I ended up with a new turbo fitted which did the trick!

[seraph]

I code is 00575 inlet manifold pressure - difference intermittent

might signify a faulty n75 valve...

check the connections to it too

[ad4pm]

Also noticed that it occured more under load when going up the steep hills round Sheffield! It would lose loads of power, I'd pull up, restart and then fine again till next time.

A main Audi dealer diagnosed it, but turbo was fitted by a specialist tuner that the warranty company directed me to use.

[marty67]

Is there any way to test these things.?

[ad4pm]

Sorry, but not sure to tell you the truth about the turbo problem I had.

I was just happy to get it sorted without the hefty bill.

Lets hope its something more straight forward that someone on this forum can help you with.

[marty67]

what is an n75 valve? where is it and what does it do?

[seraph]

what is an n75 valve? where is it and what does it do?

its a charge pressure valve, controls the boost pressure ultamately

[marty67]

where is it and is there any way to test it?