Swapping intake manifold - what else should I do

A6 All/ S6 All
#36

Does it even run at this point? The two rails are connected if im not mistaken, so somewhat even pressure is no suprise. However, even 1 HPFP alone should manage higher pressure than that without an issue. So I would honestly guess its one of the following;

HPFP not getting sufficient fuel(clogged filter, or bad LPFP)
Fuel pressure regulator faulty, just trying to constantly dump pressure.
Fuel leaking out, not able to generate pressure. But this would smell instantly and be obvious.
Both HPFP unable to generate pressure could indicate both pumps being bad/bad cam follower.(Unlikely because of the symmetry).
Faulty pressure sensors(Unlikely because of symmentry).

Does the car run? Idle? Alright? Terribly?

#37

There is only one fuel pressure sensor (G247) on the HP side. It is located under the IM. Both Engine and Engine II modules report values from this sensor.

#38

Fuel filter? Incorrect flow or low max pressure (once i had filter with lower max pressure than oem, and i get error low pressure)

HPFP have small filter similar like on pic belove, maybe they are clogged, in one of my hpfp filter had some derbs
Replacement-Fuel-Injector-Basket-Micro-Filter-for-Corsa-Vectra-S10-CF-105A-6-3-13mm-

Get pumps out, check cam followers, clean up pumps and try again. Or maybe yours hpfp pressure regulators stuck so it bypas pressure, can check that with 12v if they clicking and “pin” is moving

#39

It is idling ok-ish but not great, once it calms down it will just sit and idle. However it’s very rough at startup

#40

In most configurations cold start on the 5.2 V10 is a bit rough. On the cold start the 02s are not giving feedback until they’re warm the car is basically in open loop. So the car will idle with what is basically your last LTFT data.

The JHM tune helps this quite a bit by sorting out some of those issues.

Still your fuel pressure issue seems like it too could be playing a roll. Not only that but I’d be worried about the possible fuel starvation on WOT

#41

Mine has lumpy idle on cold start or 3 or 5 seconds and then it goes 100% smooth. I always assumed it was waiting for O2 sensor data like you just described, good to know…

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#42

If I give it any gas it doesn’t like that at all, so I’m thinking something is wrong with the high pressure pumps. I’ll have to try to pull them off to see if there is anything visually wrong with them

#43

I’d say there are no fuel leaks either from what I can tell. There’s no fuel smell and I don’t see fuel anywhere

#44

Try unplugging their pressure regulators one by one and see if that changes anything. From my expirience anything above 6 bar on idle should not have visible impact on engine smoothnes.

#45

Thanks I’ll give that a shot this weekend when I’m back in town

#46

Does anyone have an idea what’s going on with the intake flaps? It’s just showing an error. When I had the intake off the were in good shape and moving freely, could it just be a bad actuator?

#47

Poking around tonight I think I figured out one of the fuel pressure issues, don’t suppose you can just replace that clip where it threads into the hpfp can you?

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#48

Plenty of those regulators on ebay and aliexpress

I have two of them and no any issues with them
Just found this amazing item on AliExpress. Check it out! €72.70 13%OFF | Left&Right Pressure Fuel Pump 079 127 025AF 079127025AF 079127025C For Audi A6 Quattro VW Touatreg 2007-2009 4.2L GDP612
https://a.aliexpress.com/_mtyxWyw

#49

The 4.2 ones are the same?

#50

Same on 2.0 and another engines if same valve model type they all same. I have two of them, no any part numbers or letters on them, jhm tuned and no any issues

#51

Thanks, I’ll try that out to see if it does the trick.

#52

So I was able to do a bit more work on it, I replaced both of the high pressure fuel pumps and went in to try to adapt the intake manifold flaps. The high pressure fuel pumps work just fine at idle and at lower rpms, but when I do the full scan I still get (amongst a million other little electrical errors) a low pressure warning. It starts fine, doesn’t have a leak anywhere but when I scanned it after driving it gave me the code again, you can also tell at higher rpms it starts to run poorly, but it runs fine bellow around 4000-5000 rpms

000135 - Fuel Rail/System Pressure
P0087 - 002 - Too Low
Freeze Frame:
Fault Status: 01100010
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 204829 km
Time Indication: 0
Date: 2007.05.16
Time: 12:39:57

When I check them it in the vcds it shows as fine, even when I rev the engine up so I’m at a loss to what’s causing this

I also haven’t been able to reset both of my intake manifold flap actuaters, banks 1/2 keep showing an error. All of the wiring looks fine

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Could they just be broken? I move everything out of the way that could interfere with them as I installed jhm spacers when I get the intake manifold - the scan gives me this:

001632 - Intake Manifold Tuning Valve Control Circuit (Bank 1)
P0660 - 004 - Elect. Malfunction
Freeze Frame:
Fault Status: 01100100
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 204828 km
Time Indication: 0
Date: 2007.05.16
Time: 12:25:02
Freeze Frame:
RPM: 682 /min
Load: 18.0 %
Speed: 0.0 km/h
Temperature: 48.0°C
Temperature: 18.0°C
Absolute Pres.: 900.0 mbar
Voltage: 14.605 V

008198 - Intake Manifold Flap; Bank 1
P2006 - 008 - Stuck Closed
Freeze Frame:
Fault Status: 01101000
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 204828 km
Time Indication: 0
Date: 2007.05.16
Time: 12:25:06
Freeze Frame:
RPM: 704 /min
Load: 22.0 %
Speed: 0.0 km/h
Temperature: 48.0°C
Temperature: 18.0°C
Absolute Pres.: 900.0 mbar
Voltage: 14.224 V

Anyone have any ideas what I can try next? Any help would be appreciated

#53

Forgot to mention, I can post the whole scan if it will help but there are a bunch of electrical errors on it, I’m not sure what’s causing them all other than potentially the battery getting low and me pulling it out to charge it a few times since it’s been sitting so much lately

#54

Well it turns out I should read things a bit closer lol. I hooked up the connectors for the flap actuator and the sensor backwards, despite reading a thread on here about it and being sure I’d done it right :frowning:

The car runs great now, no more actuator errors or fuel pressure codes (which sort of confuses me but I’m not complaining)

Just need to fix my leaking cv joint boot, and run through the suspension (has a few clunks since I redid the everything in the front) and I may actually be able to drive it again.

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#55

Just pulled the drivers side (left) axle to replace it with a rebuilt one (found it on ebay, seems like a good piece especially since it’s only 250 dollars) but I noticed a bolt had fallen down and wedged itself between my skid pan and the engine. I don’t recognize it, does anyone here know where that would be from?

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Also my ebay axle, it seems decent if anyone is wondering what they look like.

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