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Hi folks, I bought an '04 RS6 Plus a few weeks back, so I'm still learning the ropes with it. It's low mileage (69k) and has had some light tweaks by it's previous owners (Miltek non-cat resonating exhaust, it briefly had a stage 1 map from mrc before being reset back to stock a few months later). The long journey home (500+ miles) was faultless. Now that I'm home, with some shorter more aggressive drives, I've had P0172/P0175 once, I reset & I've since had P0172 again. It's going off to a sports car specialist on Monday for a full work up, is there anything the experts here suggest I pass on to the mechanic?

I trawled through the other forums here & found some threads on RS4s with the same code, I presume there's enough in common between the 2 to be starting point?

* viewtopic.php?f=35&t=132526&p=919126&hi ... 72#p919126
* viewtopic.php?f=28&t=125771&p=857287&hi ... 72#p857287
* viewtopic.php?f=35&t=115432&p=739280&hi ... 72#p739280

Thanks,

Simon.

Congrats

Right off the hop I’d assume if it was tuned and de-tuned there may be s something you need to fine tune with correct fuel octane and maybe look at the MAF at the back into the turbo inlets and make sure those are snug.

So there are no cats?

Do you have a Vagcom?

hi not sure if it could be but a few years ago I had a similar problem and found that airflow meters hadn't been put back in correctly after the airbox was refitted

Shoppinit wrote: ↑

Tue Nov 10, 2020 9:53 am

So there are no cats?

Correct - well, I have them, MRC fitted no-cat downpipes back in November 2010 & the previous owners have passed them along. The stage 1 remap was applied at the same time & the MRC invoices also state that it was reflashed to stock in January 2013 after about 20k miles. The in-between invoices mentions some investigation around warm starting issues and some a coolant temp sensor being replaced.

Shoppinit wrote: ↑

Tue Nov 10, 2020 9:53 am

Do you have a Vagcom?

No, only Carista. The workshop it's going to is also an Avon tuning centre, so I'm hoping they can determine if it's stock or not.

Hixrs6 wrote: ↑

Tue Nov 10, 2020 1:26 am

Right off the hop I’d assume if it was tuned and de-tuned there may be s something you need to fine tune with correct fuel octane and maybe look at the MAF at the back into the turbo inlets and make sure those are snug.

Thanks!

So no cats with a standard map? Cats not mapped out?

Shoppinit wrote:So no cats with a standard map? Cats not mapped out?

No idea! More questions for the workshop

I’ll ask MRC if they have any better records.


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I don't see how you could have a standard map with no cats *without* putting the MIL on. The generic fault codes you posted don't correspond to a VAG specific DTC so it's hard to say what the underlying cause is.

First thing I would do it read the codes with a VAG specific reader like VCDS. Even the shareware version will give us a better clue than a generic reader.

Also, the MIL only comes on after a specific number of engine starts with the fault present, so that explains why you were able to drive home without the MIL. Perhaps the DPO reset the codes just before you picked the car up.

Find out what was done to your TCU, too. MRC should know if they mapped it.

The journey of discovery continues, neither TMG or TorqueTronix have been able to read the ECU, it won't even ID correctly, MRC have offered to refresh it back to stock for a small fee if I post it to them. (I need to go back to stock, or at least a milder map as the current MRC map is set for 99ron, and 99ron is impossible to get here in Northern Ireland, MRC are telling me that the refresh back to stock under a previous owner was for diagnostics & that a non-stock map was put back on). Once it's back to stock & running on fuel that matches the map, I think we can safely tackle the System too rich, which I hope will be something simple like ill-fitting MAF or something.

I'm currently eyeing up RS6 ECUs on eBay as a backup plan, any risk in fitting an RS6 ECU to an RS6+? (other than loosing 40bhp )

30hp difference but you can always put a stock plus map back on. Otherwise it’s the same ECU.

Just to follow up, I got the ECU & TCU back from MRC before Christmas, a couple of tabs on the aluminium case broken off, I suppose to be expected on something that’s been opened way more times than it was designed for, all running well, the system too rich codes have stayed away. It does feel a little less sharp, especially the gearbox outside kick-down.

While the ECU & TCU were out I sent the instrument cluster off to Cartronix to get the indicator LEDs & fuel gauge servo’s replaced, very quick turn around & very happy with the results.