N290 - Valve For Fuel Metering - Inadequate Performance

[AudiSportB5S4]

Hi All

I haven't found many references to these two codes I am pulling, so wanted to start a thread to see if others can chime in. I assume the second code is happening as a result of the first, so most focused on the first. The guidance I've seen so far is to just check the resistance on the electrical side of the plug, but I haven't seen much of what happens once that checks out or doesn't. Is the N290 a replacement? Do I need a whole new pump? I *think* this is the HPFP?

Thank you!

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2 Faults Found:

23044 - Valve for Fuel Metering (N290)
P0089 00 [032] - Inadequate Performance
Intermittent - Not Confirmed - Tested Since Memory Clear

15077 - Idle Control System RPM
P0507 00 [032] - Higher than Expected.
Intermittent - Not Confirmed - Tested Since Memory Clear

[qcrazy]

Typically means you need a new pump.

Do you have any way to log? They may or may not be related.

[THCarpenter]

I had this

Your LPFP and or hpfp are dying

You need to log to resolve which one

[AudiSportB5S4]

Gotcha okay, thanks for the input. What are you logging to check this? Any insights into the channels I need to take a look at with VCDS? Assume I'm looking for one to be bleeding off pressure a bit?

Thanks!

[THCarpenter]

I logged from DS1.

We were looking at the kpa from my LPFP. I was pushing about 100-150 kpa, where I needed to be at 600 kpa.

I also had 034 hpfp pistons in my units, so I wanted to revert back to stock

[AudiSportB5S4]

I logged my LPFP and HPFP this morning. Assuming the deviation on the low pressure side isn’t normal / ideal and potentially the cause of my N290? The HP side seems to be following fine. The blue boxed area is 100% throttle, before was rolling into it.




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[THCarpenter]

your primary LPFP is going kaput.
Find the telegram chat
https://www.audizine.com/forum/showt...t?goto=newpost
and bring this info there....we have a few guys who can help you rebuild or get you the right part numbers to get the replacement.

replacing is quite easy, as long as your tank is empty.

[AudiSportB5S4]

Sweet, thanks! I unfortunately (or maybe in this case fortunately) have plenty of experience of being inside an Audi fuel tank... My B5 S4 has gone through a few iterations of what I am running now, but agree on having low fuel in the tank! I'll join that chat, thanks again.

[AudiSportB5S4]

I decided to order a replacement fuel pump assembly for the tank. I will log over coming days to see if it fixed my deviation from spec and ultimately keeps that N290 code away. I think the high idle was related.

Overall this is a very straightforward job on this car. I cant believe how easy it was to do this… My older Audi had me prepped for the worst since on that chassis the fuel tank access was situated right beneath the rear deck so it was super awkward to work on, and the act of trying to secure the basket back into the tank was tricky. On this 2016, the whole unit gets replaced including level sender which was awesome! I bought it from FCP.

Few pics from the job and a couple things worth mentioning:
- On my 2016, all I had was one fuel line to disconnect and then the two electrical connectors on the hat. The electrical connectors are easy, the fuel line takes a little patience. I tried to harness my inner engineer and rather than try to yank the clip off, figure it out. If you push down on it, squeeze the tabs in and rotate it up and off it comes out without crazy effort. If you're romping on it too hard, you're probably not releasing the tabs enough. Online there were videos of people using pliers, I wouldn't do that since on this car if you snap anything there you'll be up a creek for sure since these aren't old school lines with clamps.
- As you start to lift the unit out there is ONE electrical connector that plugs into the bottom side of one of the plugs you see on top. Take note and don't yank the thing out breaking that or again, back up the creek. You can see the connector in my last picture.
- Goes without saying maybe, but not everyone would implicitly know this, try to have just a little fuel left in the tank. I had ~50miles to empty and there were no challenges at all.

Other than that reinstallation was simple. Take note of the tab location on the ring and put it back in the same spot. I didn't use a fancy tool to remove the lock ring since it was metal and I felt okay whacking it a little with a flathead and a hammer. Did that to loosen it as well as tighten and it was fine. Tightening I tried to get it as far as it was prior to the removal.

ALWAYS take a picture of what you go to take apart before doing it so you have a reference.. Little pro tip as it took me many times to realize this

[AudiSportB5S4]

I logged the low pressure fuel pump after replacing and still not seeing it meet specified. Now I’m thinking this is how the target AFR is achieved somehow for tuning purposes. Has anyone ever logged a stock LPFP with similar measures? RPM, Spec and actual?

Otherwise car feels great and the N290 hasnt reappeared so hoping it was justified to replace it after all!

Note: it's perhaps hard to see, but the runs on the top and bottom left graphs were longer, from 2krpm+ whereas the top right with the replaced pump was shorter, but what's visible there is all 100% throttle whereas on the top & bottom left it includes some rolling into the throttle and roughly at the same rpm do I got 100% throttle.

[THCarpenter]

glad you got this resolved.
its straight forward....until you have over 1/2 tank...and fuel pours out all over in the cabin...lol