C5 RS6 Power problems

**sbcrc86** · October 10th, 2012, 03:27

Just finished reinstalling engine and new trans and now car wont go over approx 110mph. Car has great initial grunt but stops pulling in all gears at approx 3250rpm. ANY IDEAS?

Some kind of LIMP mode for overboost?

**4everRS** · October 10th, 2012, 03:41

Pretty sure it's the capacitator solenoid that controls the flux modules which must be leaking and due to low fluid levels the resistor in the coil regulator isn't allowing Rpm's to cross 3250, as well as not going over 110mph thus obviously indicating fuse in slot 29.5 ( 3250/110 ) is bad. Replace that fuse and you should be good.

Sorry for that. Couldn't resist. I think we need a data log to get any real idea on what to give you here.

**4everRS** · October 10th, 2012, 03:43

Is there a check engine light?

**SteveKen** · October 10th, 2012, 18:25

Vag com logs should tell you if you are over boosting and throttle cutting. You might have damaged a wastegate hose?

**sbcrc86** · October 11th, 2012, 04:36

No check engine light. Just came back from doing VAG log run after Unitronic Stage 2 tune. It is definitely over boosting. VAG recorded almost 30psi...ooops. I found a frayed cloth line coming from diverter valves. Is this a waste-gate line?

**4everRS** · October 11th, 2012, 05:58

Please post the log in mbar. Blocks 3,31, and 115 are best to start. Your not doing 30 psi. You need to subtract atmospheric pressure in your area (likely about 1000 mbar) to get what the real boost pressure is.

Those line are rubber with a cloth covering. Get rid of them and buy silicone. Replace as much as you possibly can. Most audi's have this issue, and most enthusiasts use silicon to remedy.

**sbcrc86** · October 11th, 2012, 17:25

Ok, I emailed my buddy with the VAG to send me log info, off the top of my head the log read approx 2800mbar but I may be mistaken. Im at sea level so 1bar should be atmospheric pressure. Do you know where I can find a diagram of vacuum lines for turbos?

**lswing** · October 11th, 2012, 19:28

2800mbar would suggest about 25 psi, I would guess our turbos could spike that high briefly, you certainly don't want that. But some folks have been ok peaking at 19psi or so...personally I like the tune peaking at around 16psi, more linear....

**fbatwork** · May 27th, 2013, 23:21

Did this ever get narrowed down to a single source - I have an overboost / limp mode thing happening...

**lswing** · May 28th, 2013, 00:05

What codes? You check all six hoses? N75? Would be nice if op posted...

**fbatwork** · May 28th, 2013, 02:48

Okay - I am a loser... I know from all of my reading that I should be posting some logs however I am in the process of a remodel and can't find the box my vagcom cord is hiding in.

Checking on the N75 and will follow up... ripping the house apart now looking for my cable.

**Bigglezworth** · May 28th, 2013, 05:30

I have one you can use if you cannot locate yours.

**fbatwork** · May 28th, 2013, 15:40

Thanks for the offer - if I can't find it I will shoot you a PM. In the meantime the problem was a poorly routed vacumn line (pinched) on the N75 valve.

**lswing** · May 28th, 2013, 16:40

Originally Posted by fbatwork

Thanks for the offer - if I can't find it I will shoot you a PM. In the meantime the problem was a poorly routed vacumn line (pinched) on the N75 valve.

Excellent, up and running! Was the car recently worked on?

**fbatwork** · May 28th, 2013, 23:16

Yes - started with the aux cooling pump (leaking due to failed plastic pipe), timing belt, Wagner Intercoolers, valve cover (weird - small crack at the gasket), replaced the plastic oil coolant pipe with aluminum unit, cam chain tensioner guides were worn out which seemed unusual and Milltek catback exhaust... Bilstein's will be going on shortly.

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