Fuel Pumps

[Classik]

Out of interest, who does your mapping? KSF?

I trust those guys: https://www.ctf-performance.fr/

[Shoppinit]

Love the name of the village.

[Classik]

Indeed!

[Shoppinit]

Where are you at with this?

[Classik]

Big engine out job, the car just been left to my mechanic yesterday.

The to-do list is quite long:
- Brand new hybrid LOBA 650 turbos (with all surrounding seals and O-rings)
- Wastegate hoses replacement + Y replacement (metal)
- Full air leak tests
- Exhaust manifold seals replacement
- Sensors replacements (preventive maintenance): EGT, PMH, camshaft speed, oil pressure
- Alternator
- Billstein PSS9 (height at 4) + related mounting and spring discs
- New front headlights
- New fuels pumps (Walbro F274 in-tank, AEM 400lph external) - Bear in mind the car is running on E85 which explains the over-sizing of the fuel system
- Steering rack and pump replacement (the steering rack let me down during a weekend with the family )

Obviously the first 3 points should fix once for all my MAF discrepancies issues, particularly the turbo replacement as the latest measurements with the mapper showed a 50% drop of air boost between the requested pressure and the measured one. So let's cross fingers this will be the end of the tunnel for me, I've almost rebuilt a brand new RS6 with all the parts I've changed!

[Shoppinit]

Exciting stuff! Keep us updated. You uprating the fuel pumps for more pressure?

[Classik]

Exciting stuff! Keep us updated. You uprating the fuel pumps for more pressure?

I've just updated the post whilst you were replying: the reason is mostly because of E85 which is more demanding for the fuel system. But no, I don't intend to increase the pressure, 4 bar should be enough for my HP target, particularly with those hefty pumps which should prevent any pressure drop in the system. But of course I'll keep you posted with pics and comments, that's the least I could do !

[Shoppinit]

[Classik]

Here we go, engine's now out and she's ready for the big operation! New turbos are still missing (still waiting for Loba to deliver the goods), but hopefully she'll be ready before Xmas.

[Classik]

Finally some news and I'm very happy to say the first impressions are really excellent although I haven't really been able to try the car properly (uninterrupted traffic jam between the garage and the house... ), but all the horses seem to be back under the hood (still need to count them properly ), the hybrid turbos do wonders of torque even at low revs and the suspension is majestic with the new B16s (more latter on that). From an aesthetic point of view, the brand new front headlights are more than a welcome addition.
But one of the biggest news is that the discrepancies between left and right MAFs have now totally disappeared, and I mean to the point where they are close within a tenth of g/s. Hurray!!

[Shoppinit]

Yay! Great news.

But one of the biggest news is that the discrepancies between left and right MAFs have now totally disappeared, and I mean to the point where they are close within a tenth of g/s. Hurray!!

You putting that down to the turbos?

[Classik]

However it wouldn't be fun without a little problems (or 2) to fix, right?

I suppose the first one must come from a tired relay : a few hundred meters before arriving at home, the accelerator pedal no longer reacts, intermittently. Nothing happens when pressing the pedal, and I literally end my journey at idle. What is this mess? I close the car and there I realise the rear brake lights stay on ! Opening the car again and pressing the brake pedal solved the problem, but I don't like that. Fired the VCDS for a quick scan : nada..
I decided to take a little tour just to see of these issues would come again, but no. However, when I switched off the engine I heard a faint fan noise that keeps on blowing without stopping even after 5 minutes wait, coming from the side of the radio (oem). Quite pissed I simply disconnected the battery and ended the day playing with the kids which was much more rewarding..
So what do you guys think? With a bit of luck luck, it must be the same relay that controls the stop and accelerator pedals, or even this recalcitrant fan... Other things to check?


The second joke is that I still get those metallic friction / scraping noises when I pass 'quickly' on a road bumper (not clear if it comes from the front, the back or both). Knowing that I have changed the 4 shock absorbers, the front driveshafts and the front suspension arms, there are not many options left I suppose :
1 / it is possible that my wheels come out a bit too much (in fact they are vertically aligned with the bodywork) and therefore come to rub the edge of the arches during large amplitudes of suspension. So I'm going to try it out by removing the spacers (10mm on each side) even if it means losing a bit of turning radius.
2 / Rear driveshafts
3 / Tightening points and joints of the stabilization bar

Anything else I should consider?

[Shoppinit]

I suppose the first one must come from a tired relay : a few hundred meters before arriving at home, the accelerator pedal no longer reacts, intermittently. Nothing happens when pressing the pedal, and I literally end my journey at idle. What is this mess? I close the car and there I realise the rear brake lights stay on ! Opening the car again and pressing the brake pedal solved the problem, but I don't like that. Fired the VCDS for a quick scan : nada..
I decided to take a little tour just to see of these issues would come again, but no. However, when I switched off the engine I heard a faint fan noise that keeps on blowing without stopping even after 5 minutes wait, coming from the side of the radio (oem). Quite pissed I simply disconnected the battery and ended the day playing with the kids which was much more rewarding..
So what do you guys think? With a bit of luck luck, it must be the same relay that controls the stop and accelerator pedals, or even this recalcitrant fan... Other things to check?

Brake light switch. Car thinks you are pressing the brake.

There's no relay for the accelerator pedal. It's a double/opposite potentiometer setup that goes straight to the ECU. It must be giving coherent values or you'd get plenty of error codes and warning lights.

The brake light switch gives info to the ECU and TCU to see if you are pressing the brake. If it's not working properly you can get weird issues, but I'm surprised you couldn't drive the car.

The second joke is that I still get those metallic friction / scraping noises when I pass 'quickly' on a road bumper (not clear if it comes from the front, the back or both). Knowing that I have changed the 4 shock absorbers, the front driveshafts and the front suspension arms, there are not many options left I suppose :
1 / it is possible that my wheels come out a bit too much (in fact they are vertically aligned with the bodywork) and therefore come to rub the edge of the arches during large amplitudes of suspension. So I'm going to try it out by removing the spacers (10mm on each side) even if it means losing a bit of turning radius.
2 / Rear driveshafts
3 / Tightening points and joints of the stabilization bar

Anything else I should consider?

Scraping sounds like the tyre hitting the arch liner. Check for spots that are shiny / clean from the wheel rubbing it. Maybe the arch liner hasn't been put back in properly. Check the undertray, too. Plenty of bits of trim that are easy to put back on wrong or completely that can drag.

[Classik]

Yay! Great news.

But one of the biggest news is that the discrepancies between left and right MAFs have now totally disappeared, and I mean to the point where they are close within a tenth of g/s. Hurray!!

You putting that down to the turbos?

So many things have been touched and changed, so it's difficult to judge. According to my mechanic the old turbos seem still OK (not leaking, no rotation issues), however one of the silicon hoses controlling the turbos felt particularly loose. Also he changed many seals and cleaned all the surrounding pipes and hoses which certainly helped (plus dump valve return path, secondary air system, etc.).

[Classik]

Many thanks for the suggestions. You're spot on regarding the rubbing, I can clearly see a circle on the very edge of the tyre. Getting rid of the spacers should solve the problem once for all.
Need to find and check the relai now, although I haven't had any problem today. Maybe it just because the car was left without battery for more than a month?