apd 0 Posted May 23, 2004 Report Share Posted May 23, 2004 On morning start-ups i get a whiff of petrol.is this because of a split idle stabilizer breather?[the bog roll shaped thingy as refered to by mad monkee].any advice would be appreciated!CHEERS in advance.been on vag com,no faults detected. Link to post Share on other sites
FishWick 21 Posted May 23, 2004 Report Share Posted May 23, 2004 I reckon it's either perished hoses at the fuel rail, leaking carbon canister Frequency valve (N80) or the fuel tank vent hose at the junction on the inner wing under the servo has become porous.Fixing suggestion 1 just involves trimming the fuel rail hoses by 5mm if they're perished. The other suggestions involve smelling the frequency valve (under the MAF on OBD1 cars) and also the tank vent hoses.I had the same petrol whiff in the mornings too, to cure it on my car I replaced all the carbon canister related hoses and made sure the connections on the frequency valve were tight and the problem went.Another thing to check is where the CC output hose runs alongside the airbox to the frequency valve. Sometimes the airbox rubs through the hose.HTHK[ Edited Sun May 23 2004, 03:47PM ] Link to post Share on other sites
andy 0 Posted May 23, 2004 Report Share Posted May 23, 2004 what does the cc freq vave do? not familiar with these Link to post Share on other sites
madmonkee 0 Posted May 23, 2004 Report Share Posted May 23, 2004 nor me.... Link to post Share on other sites
Guest snyper Posted May 28, 2004 Report Share Posted May 28, 2004 Hi.I used to get the same thing, mine was a perished fuel hose, the one that comes from the fuel rail, down the offside inner wing and joins the hard plastic pipe, Its behind a heat resistant (silver foil) cover. The parts guy at my dealership told me it is a common fault !!CheersIan Link to post Share on other sites
FishWick 21 Posted May 28, 2004 Report Share Posted May 28, 2004 Well done Snyper. You explained that better than I did. That's precisely what I was trying to say!CC freq valve. OK, now this is on OBD1 cars, not 100% sure what OBD2 cars do but what it does is vent petrol fumes into the throttle body. It's called a frequency valve because it responds to pulse waves from the ECU. During the 1st 2 minutes of a cold start, the valve is closed and the O2 sensor is going through it's preheat cycle. At this point the ECU is ignoring the O2 sensor and just blasting a rich mixture in. Also worthy of note, at wide open throttle, the 02 sensor is again ignored. All clever stuff really.....Anyway, back to that valve....after 2 mins, you will feel the freq valve pulsing slowly as it vents vapours from the CC into the inlet. As the revs increase, so does the frequency of pulsing in the valve, and thus more vapours are allowed into the engine. Link to post Share on other sites
apd 0 Posted June 11, 2004 Author Report Share Posted June 11, 2004 turned out to be a dodgy fitted filler neck on the petrol tank.hope this helps! Link to post Share on other sites
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