does anyone know the max voltage that this sensor shoulb be reading?

not even sure there is one but any way let me explain.

for a long while now iv had a CEL accompanied by a power loss.

the fault code reads, yup you guessed it! 17705 pressure loss between turbo and inlet manifold. when the fault is cleared the car bucks and gets very lumpy at idle.

i brought the car to my lecturer (also a mechanic) and he looked over the car quickly. he spliced into a set of wires that ran down by the intercooler, using an oscilloscope he got a max voltage of 4 volts he says this should be alot higher as this is how the ecu reads pressure i.e. x voltage = y bar.

all the vacuum pipes have been check and are fine (some have been replaced), a brand new genuine DV has been put in.

could i be that something has gone wrong with the map (standard map) on the ecu?

or is this purely a failure of an engine part?

this is getting very tiring as i want to up the performance of the car but cant as this fault is still here!!!!

please help!

Edited 4 April, 201214 yr by c.h 90

Boost pressure sensors are usually pretty reliable,I would be checking for a burst or split hose under the inlet manifold,sounds like you have an air leak.

Would have though you'd need to measure the voltage under boost (car in gear on a dyno or on the road) as well as stationary?

17705 is normally a dirty throttle body or vac leak.

Have you tried cleaning the TB yet?

We checked both stationary and under load no splits visible at all it was the third time the vacuum pipes have been checked and the tb has been cleaned :-/ good news is I changed the maf sensor to a genuine one (wasn't before) and hesitation after gear change is gone and car feels a lot livelier! But when I start her the idle still jumps up to 2k rpm cold or warm and CEL is still there but haven't deleted the code shouldn't it go away after a few drive cycles??

Disconnecting the battery for 10mins should clear it I think

I'm still convinced you have an air leak somewhere,the fact it idles at 2k when started up,some pipes under the inlet manifold are difficult to get to without stripping bits off,thats where I had a split hose and I had the same symptoms as you,i ended ripping everything out,secondary air pump etc and fitting an oil catch tank.

If you can get a copy of VAG-Com on it you can run a log on block 32 which will give you the air-fuel ratio at idle (additive) and under load (multiplicative). If the additive indicates its running lean at idle then you have a vac hose leak somewhere. It should be between -10 and +10%, preferably close to zero, if it's more positive than +10% then the engine is running lean.

Otherwise it means checking all those hoses as dewaryboy said.

okay guys thanks might end up doin some stripping as ye said

and try get a hold of vag com

cheers again guys