RS4 Fuel System - Preventative Maintenance

B6/7 S4/RS4
#1

So as my car is creeping closer to 100k miles, I want to do some preventative maintenance on the fuel system.

So far I’ve got the following on my list:
Left high pressure fuel pump: 079127025AF
Right high pressure fuel pump: 079127026AB
2x HPFP to cylinder head o-ring: WHT005184
6x HPFP bolts: N10622101

I’ve made some sense of the fuel pressure sensors involved:
High pressure sensor: 06J906051C
Low pressure sensor: 06E906051K

The install of the pumps and sensors went well. The extra o-rings were not necessary as new ones came with the pumps, but they came in handy anyway since I broke one of the o-rings when I inserted the pump.

On the high pressure sensor, make sure that sucker is pretty tight. I just tightened the new one so it was aligned like the original sensor, which wasn’t enough. Of course I didn’t realize that until I turned on the fuel system and it was leaking into the valley.

I’ll order a low pressure pump on my next round of parts.

Is it worth replacing the fuel pressure regulating valve on each fuel rail? Has anyone seen failures on these? It’s pretty expensive for what is essentially a check valve. NOPE

[s]Looks like the ECS parts catalog is screwed up for the fuel pressure regulator. They list 06E906051K as a low pressure fuel sensor while the Audi parts catalog lists 06E906051K as the fuel pressure regulator. ECS says the fuel pressure regulating valve is 079130757.

What do I actually need with regards to the fuel pressure regulator(s)?[/s]

#2

Have you thought about just a rebuild kit for the pumps. The pumps can get weak over time so replaceing them is good maintenance but I think there are rebuild kits out there. JHM might have something. It could save you a little money.

The valve can be cleaned but it isnt something that really would fail for any reason.

If you get some time. It might be interesting to see what your fuel trims are before and after the maintenance work

#3

I would have gotten the rebuild kit from JHM, but their modified internals requires tuning. The pumps are only costing me $256/each anyway, so it’s not too bad.

I will definitely report on the fuel trims before/after.

#4

Sorry I thought they had oem rebuild kits as well as performance kits. 256 isnt bad.

If you really want to dig. get a log of the instant fuel corrections before you do anything and see if the new pumps push more fuel requireing more fuel to be pulled back.

#5

I’ve had an N276 valve go on me, it just happened on the weekend. The way that i noticed it was that part throttle above 3.5k to 6k was running really rough.

If you had a really light throttle below 3k or 100% full throttle, it was fine.

A quick log with VCDS showed “Rail Pressure actual vs specified” at 3.5k with part throttle was completely out.

I got the following error as well

1 Fault Found:
000136 - Fuel Rail/System Pressure
P0088 - 001 - Too High - Intermittent
Freeze Frame:
Fault Status: 00100001
Fault Priority: 0
Fault Frequency: 24
Reset counter: 255
Mileage: 103721 km
Time Indication: 0

I replaced the N276 on both fuel pumps and that has seemed to of solved it.

I still need to push it hard, like i did on the weekend but for now it hasn’t thrown the code and the same logs now produce the correct result.

#6

Wait, so are the fuel pressure regulator valves in the high pressure fuel pumps? I was under the assumption they were connected to the fuel rails under the IM.

#7

Yes, there are fuel pressure regulator/release valves that are located under the IM as mentioned. They are a mechanical valve designed to open at 140Bar and flow from high pressure fuel line to low pressure fuel line. Part Number #079130757.

What i was referring to the is the fuel metering valves in the HPFP. If you read the Audi Self Study program Audi.ssp.921603 page 26 they refer to them as N290 & N402. I was referring to them as N276 in my previous post because that is what they will show up as in the VCDS logs when there is an error.

You can’t buy them individually, you can only get them on new HPFP.

There is a low pressure sensor 06E906051K that you have referred to, that is located under the cover next to the oil filter, were the fuel comes into the fuel rail, that measures low pressure from the LPFP in the tank.

There is a high pressure sensor 06J906051C that is located in the valley under the IM, as you describe, from my under standing, that is were the “Rail Pressure (Actual)” is read from in VCDS.

To answer your original question, would you replace the fuel pressure valve #079130757 on each fuel rail, my answer would be no. I’ve done both low & high pressure sensor before because i was trying to troubleshoot a problem but in the end it didn’t make a difference (pinched harness).

I would do the two HPFP 100%. The high pressure sensor 06J906051C under the IM if you wanted to because you may have the IM off. Low pressure is easy to get to if needed. I’ve never read anywhere about the fuel pressure valve going.

Hope that helps.

#8

Ah okay, thanks for the clarification. Everything will be here tomorrow.

#9

The term you might have seen is rail valves. There are two rail valves that open over 140bar they are the brass valves on the fuel rail. You can pull and check them but they are a simple valve

#10

Does anyone know how to check the lift pump duty cycle on the RS4? The normal block 106-2 just says ON or OFF.

#11

Must be something with my ECU… I got another MY 2007 owner reporting that 106-2 shows the percentage value for the duty cycle.

Could it have something to do with my EVAP system not showing readiness?

Could someone with the JHM tune check that block for me?

#12

I can check tonight after work.