1.8T with K04-064 - Lean mixtures

[marto7]

Hello.I have A4 1.8T with k04-064 turbo.The fuel pump is Walbro GSS340 (255lph) and Bosch 630cc injectors.The car is converted to B5 return fuel system with B5 fuel rail with 4bar FPR.I leave the fpr to the atmosphere to keep the static 4bar fuel pressure.The problem is i have lean mixtures even on 4k rpm.When the car wants 0.830 afr , the car give 0.930. Its hardly goes lower than 0,900. Tha lambda control (%) goes to 25%.I dont know where is the problem injectors or the fuel pump.Both are brand new.The fuel pump i bought before 2 years but it was seating in the box all the time before i install it.Injectors are calibrated and all the hoses are 8mm diameter.Here is 2 logs.I go to 5k rpm because i see the mixes are lean and im scared to push more.
First log - 001 and 031
Second log - 001, 031 and 032

[A4-Mike]

Hook the FPR up to the intake manifold so when you hit boost it keeps the pressure up in the fuel rail.

02 A4 B6 1.8TQ Stage 3

[marto7]

But maybe i need new Ecu tune for this ?

[A4-Mike]

But maybe i need new Ecu tune for this ?

Yes you will need a new tune, as it won't be static 4 bar anymore

02 A4 B6 1.8TQ Stage 3

[marto7]

But if the fuel pump cant deliver enought fuel on bigger pressures the problem will be bigger.Another thing that i thinking about is if i switch to 3bar FPR can I get more fuel because on lower pressure the pump can deliver more fuel ?

[marto7]

I think the problem cant flow enought on that pressure.I tried to give the pump 12v and try how much fuel can flow from return line.The results was 350ml for 10 seconds.
I checked the fuel pressure and its constant 4bar on the rail.Even when im on boost on 4500rpm the gauge shows 4bar but vcds show 25% lambda correction and lean mixtures
Can i try to install two pumps with 3-way fitting ? The right place of the tank will be the original A4 1.8T pump and on the left part of the tank i will install the walbro.What do you think about this?

And can i run both pumps on the wiring of the original pump ?

[V70R]

First off, hook a vacuum line up to your FPR. Your injectors will thank you as they don't need that much pressure at idle and/or normal driving. You could try a different FPR, decreasing the FPR 1 bar in pressure will increase the rate fuel pump output.

If you're not receiving the same voltage at the pump when compared to the battery, relay the pump ASAP.

Before anything blows up, what are the specs on the build? Is your tune matching fuel mods I.E. injector CC, FPR, MAF sensor diameter, etc etc.

[marto7]

My tune is matching all the stuffs that i have.Differennt turbo, MAF housing and injectors.The tune is for 4bar static fuel pressure so i leaved fpr to the atmosphere.The wiring to the pump is the original one, so i think i already have a relay.
I need to meassure battery voltage and after that fuel pump wiring to check if the Voltage is the same ?

[Gin+]

I'm confused based on what I see in that log and what you're describing.

What do the trims settle out to during normal part-throttle cruising, in other words when does it run lean, all the time or just WOT?

[marto7]

The car is lean only on WOT.When im cruising the trims on part throttle is 8% maximum and lower than 5% idle

[A4-Mike]

When I had my car tuned I was running 58psi static (4 bar) and under 25psi of boost the fuel pressure would drop to 33psi, once the FPR is hooked up to the intake manifold fold when on 25psi of boost it would rise to 83psi and FPR will bleed whatever the injectors don't need back to the tank.

02 A4 B6 1.8TQ Stage 3

[Gin+]

Id check that your maf is scaled and functioning correctly for your tune. Also be sure the injectors are calibrated correctly in the tune. If you’re seeing 4 bar fuel pressure at the rail when on the throttle then I’d assume the pump to be fine.

[Gin+]

When I had my car tuned I was running 58psi static (4 bar) and under 25psi of boost the fuel pressure would drop to 33psi, once the FPR is hooked up to the intake manifold fold when on 25psi of boost it would rise to 83psi and FPR will bleed whatever the injectors don't need back to the tank.

02 A4 B6 1.8TQ Stage 3

Definetly has its benefits.

[marto7]

But i need a new tune when i hook the fpr to the manifold right ? My injectors are 2-3% idle and 8% partial throttle on channel 032.I think they are calibrated perfect.The pressure is 4bar all the time, where do you think its my problem ? Also i see on the channel 115 that my turbo have 1.5bar boost on 2400rpm but i cant feel nothing before 3500rpm.Why can this happen ? And what i need to do with the fuel ? Here is the log on 002, 031 and 115: LINK

[Gin+]

8% partial throttle

Not normal.

[V70R]

My tune is matching all the stuffs that i have.Differennt turbo, MAF housing and injectors.The tune is for 4bar static fuel pressure so i leaved fpr to the atmosphere.The wiring to the pump is the original one, so i think i already have a relay.
I need to meassure battery voltage and after that fuel pump wiring to check if the Voltage is the same ?

Yep. Check terminal 30 or manually check the battery voltage with an ohmmeter, and you should have the same voltage at the pump, too.

[marto7]

How to check the pump voltage ? Can i meassure it on the fuse of the fuel pump ?