Question from a new owner

[Dippy]

Time to eat humble pie. I'm totally wrong. I thought that the F hose was the 'T-piece' arrangement, as in later cars like mine the metal pipe is extended so that there are only 2 flexible hoses, not 3!

I found this website:

web page

Which shows the F-hose clearly.

Now I'm going to have to check mine!!!

[Dippy]

I've only eaten half of the pie: I may have been wrong about the location but I'm right that later S4s don't have the F-hose. I just checked mine and its a single pipe, which also looks narrower.

I've researched this a bit and this hose is for 2 systems: The ACF fuel vapour control and the crankcase breather. But the bottom line is that the hose is connected to the intake manifold so you don't want any leaks. The fact that Audi have completely redesigned this part of the engine (the crankcase breather line has been moved), shows that clearly the F-hose is a weak point.

[jubsees4]

What would the symptoms be if any of the above were happening (ie split hose or tbb etc)?

As I shall be using QST on a regular basis, I'll get them to check out all the hoses etc as a matter of routine anyway. Especially this "F" hose that has caused so much discussion! Thanks for the joke, PC now in for repair to clean spat coffee off keyboard / monitor.......

On a similar note, how often should oil be changed?

[DavidT]

Any air leaks in the system will make the turbo's work harder and therefore risk damage to them.

Larger leaks are beyond the turbo's capacity to make up and will cause a reduction in boost pressure and therefore power.

One way to spot leaks is the sound of rushing (leaking) air. Try driving with the car on boost with the windows down and listen for the sound. My dealer suggested it, worked for me.

Boost gauge is also a good idea.

[Dippy]

Agreed,

Altough a boost guage can help in driving (e.g. when you're waiting to overtake you can reduce lag by holding it just off boost rather than all the way off), I find it nice to just know that I'm getting full boost and therefore don't have a major air leak. Minor air leaks are not so easy to notice so you need to rely on regular inspection.

I also recommend getting VAG-COM. It's good to regularly check for DTCs, plus checking MAF output.

[sitas3]

I've only eaten half of the pie: I may have been wrong about the location but I'm right that later S4s don't have the F-hose. I just checked mine and its a single pipe, which also looks narrower.

I've researched this a bit and this hose is for 2 systems: The ACF fuel vapour control and the crankcase breather. But the bottom line is that the hose is connected to the intake manifold so you don't want any leaks. The fact that Audi have completely redesigned this part of the engine (the crankcase breather line has been moved), shows that clearly the F-hose is a weak point.

Dippy,

do you by any chance know if this 'weak spot' F Hose can be replaced on pre-2001.5 cars with the single revised piece you refer to above?

[Dippy]

Probably, but the piece in question is the intake manifold so that's a fairly major investment!

[KayGee]

Between the e and g hoses, LOL.

I have a bailey recirc DV on my Punto GT, due to crappy OEM Bosch part (which incidently looks remarkably similar to the crappy Audi/Bosch items) but it's damn noisy, which is great on a metallic gold Punto GT but not very "Audi" IMHO. Does anyone do a silent\quiet DV for the Audi?

rgds

K

P.S Upsolute man coming next Monday....with luck.

[Nige_RS4]

All the 2.7t BPV's (not DV's) are relatively quiet, as they are closed loop valves. I thought the Punto and the like all had atmospheric valves ?? There is a mfr in the states that has developed a noisey BPV for the 2.7t specially for the boy-racer brigade

There are uprated Bosch valves available for our cars (ask vagparts for a 710N valve) or go with the Forge or Bailey piston BPV. One's £17, the others £75 - and you need two of them - your call!

[KayGee]

No, the std Punto GT uses the same type of Bosch recirc valve unit the Audi uses. I eventually replaced mine with the Bailey Recirc which was about £100 but is still going strong 2 years and 40K later. I replaced the OEM Punto one twice in 10K then gave up with them. The thought of having to replace them every 10K really doesn't appeal. Need to open the bonnett Sat anyway so will look at them and the TBB.

Thanks

K