Hissing tdi

[twist123]

Hi Guys,

Hoping someone can help. Still the ongoing saga with the car that cuts out at ignition. Changed EGR and checked intake manifold (no crud) over the weekend. Car ran fine since then, this afternoonI started it after driving a while and it went lumpy at idle kinda like fuel starvation which it was doing before, I did what I did last time and unplugged the MAP sensor, started again and all was fine.

Plugged MAP in again, same thing, idles then dies. I noticed when the car died and I stuck my ear to the drivers side headlight a hissing, took off the air intake nozzle and it was definitely coming from infront of the airbox and behind the headlight. Looked like a few pipes go into some thingies, are these the N75 or ? As I think they may be the problem.

Drove car home without MAP sensor plugged in, obviously no power but it never died once in 20 odd miles. Strange thing is I plugged the MAP sensor back in after the run and all seemed fine again, put ear against airbox area and hiss was gone! Gotta be intermittent, so thinking a valve of some sort?

Thanks in advance guys for all the help with this PITA problem.

 

[dolcevita4]

have you not had vag com on it? vag com would show you if it's n75 and n75 is placed excatly where you described it if it's a 1.9 tdi

 

[twist123]

Hi, thanks for the speedy reply. I did Vagcom it and nothing came up, only the MAP sensor which I unplugged so it logged. Wondering wether the N75 is kind of knackered as its intermittent but not logging?

Its a 1.9tdi, 130.

 

[twist123]

Is it easy enough to change the N75 as it looks there are 2 valves next to each other when I checked? Any other ideas?

 

[dolcevita4]

yes there are two next to each other, as far as I remember the one on the right ( closer to turbo is n75 ) might be wrong on that so get it checked, its a straight forward swap, shouldnt take long however when mine was dodgy it didnt hiss and also there was a fault on the vag com. Maybe one of your pipes have melted or have a hole? It happened to mine, the one going into the egr, it melted because it was touching the engine...

 

[twist123]

Thanks again mate, do think its either N75, MAF or leaky hoses, but hiss makes me think N75 or hose split. My wife said first time it started it shook violently then died, after that much less shake but still dying. Intermittent issues are such a pain especially now the stupid hiss has gone again. Think Ill have to wait till I can check everything out during daytime.

Dont want to pay Audi labour charge and independents just VCDS it and say "We cant find any codes" "nooo REALLY!!??" "Thatll be £50"