Question from a new owner

[jubsees4]

Hello fellas - my first post, hope you can help.

I've just purchased a 4yr old S4 from a member of my wifes family. I've had it 2 weeks and although impressed with the car, I felt it lacked oomph. So I took it to QSTuning in Haywards Heath who diagnosed a faulty Airflow meter. They duly replaced the item and WHOOOOOOAAAAAAAAAA, I shall be in a ditch very soon.

My question is this: is this a common problem and how often am I likely to need to replace this? Are there any other "minor" probs I can expect?

Many thanks
JRB

[Joshie]

Hi Mate - welcome to RS246.

The MAF or airflow meter is weak and does require repacement from time to time although mine lasted 58000 miles this is rare.

Other things to watch out for are the TBB (throttle body boot) which is the large rubber boot at the front of the throttle body (underneath the S4 Biturbo cowling). They often split but if your car is feeling quick and especially since it has just been into QST it's probably OK but keep an eye on performance and perhaps even replace with a reinforced SAMCO unit for peace of mind. A split is difficult to detect without removal although removal and replacement is dead easy.

Other common issues are the divertor or dump valves - replacement valves are dead cheap but standard ones are weak - many S4 owners replace with Forge or Stratmosphere valves as they are more reliable.

Anything else just ask.

[jubsees4]

Cheers Joshie! Will keep an eye on things. Have got to say that at the moment it is flying. But how long before the temptation for more power surfaces it's ugly head.... I do feel the need to keep Scubies & Evos at bay....! [img]images/graemlins/smirk.gif[/img]

[SimonS4MTM]

Dont waste any time before you get it modded. It really does transform the car and turn it into a real rocket.

There is nothing better than having 500Nm of torque under your right foot, and the ability to do 175mph (laws permitting) [img]images/graemlins/jump.gif[/img]

[wazza]

If you have nothing planned on Sunday I can show you how it goes. [img]images/graemlins/grin.gif[/img]
As you aren't too far away see here. [img]images/graemlins/thumb.gif[/img]

[Dippy]

but if your car is feeling quick and especially since it has just been into QST it's probably OK but keep an eye on performance and perhaps even replace with a reinforced SAMCO unit for peace of mind. A split is difficult to detect without removal although removal and replacement is dead easy.

Joshie,

I don't agree with your logic. Firstly since the car was suffering from a bad MAF, it'll feel quick now even if the TBB is torn.

Secondly as you pointed out, a tear is often only found by removal and inspection. QST would have identified the bad MAF very easily, and therefore may not have been inclined to check the TBB.

Finally remember that the S4/RS4 ECU will compensate for an air leak by keeping the wastegates closed longer. Therefore there may not be any noticable loss of performance depending on the size of the leak.

Apart from that you almost seem like an intelligent chap [img]images/graemlins/tongue.gif[/img]

My advice is to change the TBB and DVs immediately. They are both low cost items but failure can be very expensive.

[Golich]

My advice is to change the TBB and DVs immediately. They are both low cost items but failure can be very expensive.

I see where your coming from Dippy Hhmm I suppose it's not a bad insurance or peace of mind fitting £35 worth of parts i.e. £7 for the TBB and £15 each for the bosch DVs. Safe in the knowledge that they should last at least months or between services have them specifically checked. This idea becomes more acceptable if you're doing it yourself or paying sustantially less labour rates than Audi's typical £75/hr.

[jubsees4]

Oh great, now I'm paranoid that the next time I start it the whole thing will disintegrate around me!!

It does feel stupidly quick. To be honest, having driven the wifes 1.6 Polo for the last couple of years, even an S4 with a faulty MAF felt quick!!

QST did suggest (before they looked at the car) that the problem could be a split hose etc or a faulty MAF, so I believe they would have checked out any possible air leaks. I may check with them to make sure but probably only after I get beaten away from the lights by a "Sporty" Saxo......

[Dippy]

Jubs,

No need for paranoia. However the suggestion IS sensible. The TBB has a reputation for failure, as do the Bosch DVs and the F-hose on older cars. Also the pipes from the intercoolers can get loose too.

So replacement/tightening of the hoses is to be recommended. All except the intercooler hoses are easy to do (the ic hoses can only be got at by removing the headlights, but even that is not very difficult).

As for what QST did or did not check, that's easy - why don't you ask them?

[SimonS4MTM]

Can you explain where the F hose is?

[Dippy]

It's between the E and G hoses.

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[Dippy]

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[Dippy]

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[Dippy]

Seriously though...

If you take of the cover over the DVs, look for the small hoses that come out of the DVs. On newer S4s these just go to a metal pipe which ends in a 'T' piece. However on earlier S4s an 'f' shaped hose was provided instead. Being a special hose with a join, it is prone to deterioration and could cause a vacuum leak.

[SimonS4MTM]

My car is a 98, the small hose goes to a T piece then to a metal pipe running towards the back right of the engine to the vacuum control unit.

Is the F hose near the T piece or at the back of the engine?