RS2 not at its best, any clues ??

[RS2junkie]

Hi,

Have noticed my RS2 is not as sharp, a bit under powered and generally not feeling right the past few weeks.... Here are some of the symptoms

Power is OK at low revs but when I give it the beans its seems OK up to about 3,000rpm, then it feels very flat and gutless, there is not the kick in the back I used to get.

It feels like the turbo is not giving boost at high RPM (or holding boost). It sounds as it the dump valve is dumping the boost rather than holding it (if that makes sense ?)

I also notice it is not revving so freely at high rpm either.

Last few days, when left overnight, it has not been starting on the first turn of the key as it used to, starts on the second turn fine !!

Fuel consumption is still ok at about 220 mile on a tank.

Pulled the fault codes and it had a mixture fault,but no specific reference to a sensor (sorry a bit vague !!)

Any clues, where do I start ??

Boost leak ?

Plugs ?

Coil Pack ??

Please help ?

Paul

[Ross]

Similar to what I recently had, mine was a dead MAF, except I did have the MAF signal code. The mixture is usually unmetered air entering the system throwing off your fuelling, if you can hear air escaping as well then that is your best bet.

Definitely get it pressure tested, a boost leak sounds likely if you can hear air escaping, check the DV as well. It's worth checking all your jubilee clips are tight, haven't snapped or slipped off the hose end, if you've got stock hoses check for splits as well.

Let us know how you get on.

[UrS4boy]

"Mixture fault" is your best clue. If you gave us the exact code it would help us help you.

In the meantime, I agree with Ross re: pressure testing. However, I disagree about unmetered air *entering* the intake track. More likely it is metered air that went by the MAF but never showed up at the engine because there is a boost leak between the turbo and the throttle body. This only happens at certain boost level because the split in a hose only opens up at that pressure. Normally it is fine (when you are running in vacuum) so your fuel economy hasn't suffered - just your hp.

2413 (Blink Fault Code), 00561 VAG1551/2 Fault Code Number
Mixture Adjustment, Adaptation limit exceeded, Adaptation limit not reached, Leakage in exhaust system before 3 Way catalytic converters, Incorrect signal for Mass Air Flow Sensor, Spark plugs, ignition coil(s), or Ignition Coil Power output stage malfunctioning. Symptom: Rich mixture, increased fuel consumption

[re2500]

My initial thought would be a boost leak.

[AndyP]

If it's not a boost leak, I'd go with a dead lambda sensor.

[prj]

If it's not a boost leak, I'd go with a dead lambda sensor.

That wouldn't affect it on full throttle.

[Ross]

Not trying to be pedantic but on idle / cruise with vacuum it will suck air in a split hose, causing poor starting, bad idle and rough running in those conditions. You hit a 'sweet spot' where intake pressure is ambient, then yes you lose metered air to the extreme when you come on boost...

[UrS4boy]

Not trying to be pedantic but on idle / cruise with vacuum it will suck air in a split hose, causing poor starting, bad idle and rough running in those conditions.

Depends on the hose. With the C4 UrSs, what you describe happens with the MAF to turbo hose when it is split, but never with a split on the Michelin Man cross-over to intercooler hose. They typically split (due to oil accummulations rotting the rubber in the valleys of the corrugations) but are fine until you get above a certain boost level when the split opens up (and then reseals off throttle). Eventually there is a massive hose failure which makes finding the problem *much* easier.

[RS2junkie]

Update and fault codes

Hi all
Appreciate your advice, will be getting a pressure test shortly .

I had the fault codes downloaded and this is what I got !

00561 - Mixture Adaptation 14.10 Adaptation Limit Exceeded (Intermittent)
00561 - Mixture Adaptation 13.00 Adaptation Limit (Nul) Not Reached
00319 - Intake Manifold Pressure Sensor (G71) 17.10 Control Difference (Intermittent)
00537 - Lambda Oxygen Sensor Regulator 11.10 Control Limit not Reached (Intermittent)

As the engine was not running I also got an engine speed sensor fault but I ignored it

I also got a fault on the Engine Immobiliser, now this could explain the poor starting. Is this the Audi Alarm / Immob or my Conlog ???

Does this give any clues.

The symptoms are the same, lack of power at high RPM, poor running and starting, MPG is OK ???

Thanks for your help.....

Paul

[AndyP]

Have you done a leak test yet?

[RS2junkie]

Not yet Andy, have not had time, might have to "make" time as it is doing my head in !

The immobiliser fault is wierd, happening more often now...

P

[RS2junkie]

Hi,

Any clues from these error codes ???

Thanks

P

[prj]

Yes, you have a boost leak.

[UrS4boy]

Hi, Any clues from these error codes ??? Thanks P

With these codes:
00561 - Mixture Adaptation 14.10 Adaptation Limit Exceeded (Intermittent)
00561 - Mixture Adaptation 13.00 Adaptation Limit (Nul) Not Reached
00319 - Intake Manifold Pressure Sensor (G71) 17.10 Control Difference (Intermittent)
00537 - Lambda Oxygen Sensor Regulator 11.10 Control Limit not Reached (Intermittent)

As prj suggests, a boost leak. The reason you get at least the 561 and 537 codes is a certain amount of air went by the MAF, the MAF told the ECU how much air and the ECU calculated the appropriate amount of fuel for the RPM and boost level and that amount of air. *HOWEVER* there was a leak in the hoses, etc. between the MAF and the engine so the amount of fuel that was injected was too much for the air that actually arrived. The ECU finds this out after the fact via the Lambda O2 sensor reading on the exhaust gases and says "WTF?? What happened to the air that was supposed to arrive?". The ECU tries to correct the Lambda reading by dialling back the fuel, but it can only do so much before the adapation limits and control limits are reached. At that point, the ECU gives up (saying, "Hey I'm trying and it still isn't working. Don't blame me" and throws a code (or three) while trying to cope with the situation. In the meantime, you probably get off the throttle and the boost leak re-seals itself (engine is probably in vacuum) so the ECU continues on without more issues. But the boost leak problem is still there. You need to find and fix it. And then clear the codes.

And of course, ECU's don't talk.

Or do they?

(You just have to listen to what they say (the codes))

[RS2junkie]

Thanks guys, plenty to go on there, just need to do the leak test, will let you know how I get on ...

Paul