Audi A6 1.9TDI with loose of power

[josantos04]

Hi there my A6 is with low power and I don't know what to do.
Changed the MAF and keep on the same. You can feel the boost at almost 3000rpm but till there there is really low power. One thing that happens is when I accelerate there is a relay sound when it gets to 2800\3000rpm and this is when you feel the boost.
Can any of you give me some help?

thanks

[ford776]

Have you tried the N75 valve that controls the turbo boost? On mine, A 1999 1.9 tdi, it's below the turbo, with lots of vacuum pipes going to it.

Andy

[josantos04]

there is two similar ones.
one on the front of engine and other one on the back.
the front one is black and white and the one on the back is just black.
Do you know hitch one is the n75?

thanks

[STEWY L]

Hi there my A6 is with low power and I don't know what to do.
Changed the MAF and keep on the same. You can feel the boost at almost 3000rpm but till there there is really low power. One thing that happens is when I accelerate there is a relay sound when it gets to 2800\3000rpm and this is when you feel the boost.
Can any of you give me some help?

thanks

i would check each and every vacuum hose first. they are known to crack/perish, and if they have gone hard they may leak on the push on connections on anyone of many valves/sensors.
you have not mentioned "limp mode",or"safe mode",and so would assume that the turbo vanes are not stuck, which i believe would mean that the turbo would spool up later,but then "overboost" hence the ecu going into "limp"or "safe" mode.
if these small vacuum hoses seem ok,then get it fault code read.
it will save you a lot of hassle,and expence,as you seem quite willing to change sensors "on a hunch",the "MAF, as you call it,being proof of that.
check the small vacuum hoses,and then spend about £30( 29 euro!)
to get it read. believe me,it will save you so much hassle.
best regards,
stewy.

[josantos04]

how do I check if the car goes on limp or safe mode? there is any light or message coming up when that happens?
sorry about this stupid questions but i'm not very good with this terms.

thanks

[STEWY L]

how do I check if the car goes on limp or safe mode? there is any light or message coming up when that happens?
sorry about this stupid questions but i'm not very good with this terms.

thanks

if you are driving,and have good power, then suddenly find that the power is lost, it would then make you think that you have something wrong with the car and you would stop the car to take a look at the engine.
you would find nothing visible,but,upon restarting your car the power would be restored until such time as the turbo "overboosted" again and it would again loose power having being put back into "limp"or"safe" mode.
this is the ecu protecting the engine from further damage,by limiting the fuel and restricting timing advance.
it allows you to limp home should you be "on a promise"
hope i have explained it well enough for you to understand,i know it's very complicated and i'm not very good with words myself.
best regards,
stewy.

[josantos04]

I know what you mean.
thanks for your help

regards

[STEWY L]

it probably will be a sensor,but it would cost you a lot of cash to change them "one at a time",and you had no luck with the MAF, so i would check the vacuum hoses,it costs nothing,and you may find a damaged hose that can be replaced very cheaply.
but then, if no fault found with the hoses,i would get it "fault code read".
some of these sensors are VERY expensive,and you have other things to spend your money on.
i know we have.
good luck,and best regards,
stewy.

[shaunebabe]

hi mate sounds like the same problem i had on my avant 1999 1.9 tdi i was having the same prodlem went in to evrything took it to a good audi garage got pluged in did not bring any falts up or codes even the garage said it was fine anyway after doing some investergating it tured ouy to be the cat replacerd this like a diffrent car please let me no how u go on thanks shaun