Car running lean

[prj]

Time for me to ask for help.
My car seems to run lean (with different chipsets) and I am slowly running out of things to try to improve the situation.

AFR's under boost (1.2-1.3 bar) 12.9-13.4, when starting to accelerate 15.8-15.9.
This chipset should run closer to 11.5-12, not 13. At 2900 rpm in that graph is knock, that is why motronic pulls some boost. Others run this chipset at higher boost levels without issues.
This is a generic chipset, I removed my modifications. Ambient temp was about 5 degrees celsius.
Second gear pull:


Background info:
UrS6 AAN, stock injectors, stock turbo, Motronic.
Engine rebuilt two months ago, brand new MAF, RS2 exhaust manifold.

Things I have tried so far:
1. Different ECU software, that I have seen run richer on other cars.
2. I have absolutely no boost leaks. System is completely pressure proof up to 2 bar starting the MAF-Turbo hose.
3. Different FPR
4. Different MAF
5. Injectors cleaned
6. Fuel filter changed

Today I will temporarily separate the breather system from the intake and also measure my fuel pressure (maybe my pump is going out), then also try totally stock ECU software and measure AFR under boost (it would be helpful if someone could give AFR's with stock software).
If this does not help, then I am out of ideas.

[GazzaG60]

fuel pump.

towards the end on my stock aby pump it leaned a fraction. also dropped off earller on boost. when i put the o44 in it was overfueling in every area. no other changes

[twoqu]

http://forums.quattroworld.com/s4s6/msgs/24327.phtml

[prj]

Mmm... you can really see it in the end getting leaner! Even though it should be going richer, as the turbo starts producing more heat.

I'll see how my fuel pressure behaves today... If I see it dropping off, I'll order this:
http://cgi.ebay.co.uk/GS341-HRC-255-...item3a5f4a88be

It uses a Denso pump inside (which is of good quality) and it is not as noisy as the 044. Plus it's 55 quid shipped.

[prj]

http://forums.quattroworld.com/s4s6/msgs/24327.phtml

Thanks.
I will measure the voltage at the pump as well.

[EspenW]

Other possibilities:
Voltage to fuel pump (also check under load, as it might drop drastically)
Clogged injector(s)
Calibration of wideband
Ethanol in fuel
Try a pull in higher gear, as the high sweep rate in 2nd causes the mixture to be leaner, due to the xTau effect.

[prj]

Other possibilities:
Voltage to fuel pump (also check under load, as it might drop drastically)

Will check.

Clogged injector(s)

Injectors cleaned with ultrasound and special fluid on a stand three months ago. Also I changed my fuel filter. So that's not clogged either.

Calibration of wideband

Possible. But my controller does not require calibration. I will try another sensor today as well. Even though mine is almost brand new.

Ethanol in fuel

Some parts of it are there anyway... but... that's a good idea. Maybe I just have shoddy fuel?

Try a pull in higher gear, as the high sweep rate in 2nd causes the mixture to be leaner, due to the xTau effect.

Higher gears are similar, but I will try it and log.
I have a slightly leaner chipset in now...

[Jamo]

My bet Voltage at the pump, may have to do a relay install to wire it directly to the battery

[prj]

But how come it is fine from the factory then?
Does something corrode somewhere?

[Rusty]

At stock power the voltage drop isn't enough to affect performance. The more you expect from the fuel pump, the more the voltage drop causes issues, it is a motor afterall and if you drop the voltage, you drop RPM and thus flow.

Anyone who's done a relay conversion on stock VW headlights will testify that stock wiring can be poor quality under load.

[prj]

Thing is though, it is lean pretty much all the time.
Also, I get slight stutter at idle, but no idea if that's connected.

[Rusty]

Worth getting the voltmeter out for 5 mins to check but sounds like you've got another issue. Air leak is possible but depends where the MAF is for that to work out lean and it wouldn't affect idle particularly... odd for sure.

[prj]

I am pretty sure I don't have an air leak...
I get odd stutter and AFR's jumping a bit during the stutter.
I wonder if one of the injectors might be slightly bad...

Also, my idle is higher than normal.
I tried different ECU's as well... same result.
But like, the idle issue is not bad or anything. You barely feel it. Every now and then it vibrates slightly and AFR's bump up a bit richer...

[4WheelDrifter]

Fuel breather ok?

[prj]

Measured voltages - when charging, it's close to 14 volt, at the pump it's 12.8 volt, sometimes dipping to 12.6.
This is more than enough for the pump, so I'd rule out the voltage.

Also blocked the breather system entirely away from the intake system. That made a small difference (probably a leak there somewhere)...
I will just install an oil catch tank anyway, so that'll be plugged from now on, but even so.

2nd gear:


3rd gear:


This is different to the software posted in the first post. It's leaner. With the breather pipes plugged in I had about 0.3 leaner mixtures. And yes, there is probably a leak there, as all the rubber hoses are quite tired.
But even with that out of the way - still lean... will test a different wideband sensor and controller tomorrow (VEMS Round). If that shows the same, will order a new fuel pump (god knows when it was changed anyway). And if it's still lean after that, I'll drive off a cliff or something :/