urquattro with AAN running lean

[x6rs]

got an AAn engine with rs2 injektors,k26/27 turbo, rs2 EM, and another chipset.

also have an wideband lambda sensor, at full throttle and 1.5bar boost it shows 10.9 AFR until i get over 5000rpms then it starts to get leaner and leaner for every rpm. ive had afr around 15 sometimes at ca 6500rpms.... thats not good.

on good days it works just fine, reading ca 10.9-11.3 on every rpm at full throttle, but bad days it runs lean..
i rather see it run rich to hold the temps down a bit(its not my daily driver, its my trackday car), 10.9 all the way would be perfekt i guess

i have checked for leaks, none.(also if i had a leak wouldnt the afr show rich?)
check the plugs, all looked good except cyl.5 wich was grey/whiteish
no misfiring.
new fuel filter

going to hit the track at thursday and over the weekend so im in a hurry.
also i heard something about if the alternator didnt work properly the pump and injektors wont get enough power and it could cause this.

i got an almost new MAF i can try.

so what do you guys think?

[x6rs]

when i think about it, the bad days have been when it rains or have been raining
also the alternator belt is a bit loose so maybe it could be slipping on higher rpms?
gonna mount a new belt tomorrow and tighten it properly
also mount a new air filter and clean the MAF(really dusty inside) or replace it

on thursday its track time and i shure want to rev the beast past 5000rpms

[rs200]

there could be problem with altitude sensor or air tem. sensor on intake manifold..
is this problem became when you change this chips,turbo..
or this problem came now , and you drive on this setup for a while, and before was all ok?

[x6rs]

yea maybe it is a sensor problem. altitude sensor located where?
i used to have hohnester chips in the car, but i thought it ran a bit lean with them also, as i mostly will use the car for track i dont need to worry about fuel economy so i wanted a richer mixture so the engine would run cooler, so i changed the chips to some unmarked chips that a friend of mine uses, 400hp for rs2, i got same engine specs as he does, he has used it in his daily driver for a couple of years now and no problems at all, his car runs a bit richer.

but no the problem probably already existed before changing the chips.

[S2central.net]

How healthy is the fuel pump, and what voltage do you see at the pump with engine running ?

URquattro has thinner cable to fuel pump than S2/RS2... couple that to a tired old pump and the flow is reduced... giving lean running under load.

[x6rs]

i havent checked voltage on pump yet, dont really know how to acctually, is ther some cable i can check from inside the car, would be nice to see if it changes under load.
strange though that under full load up to 5000rpms it runs really rich, im seeing 10.9 all the way up to 5k rpms

i also havbe problem making it boost more than 1.5 bar, running a really hard spring and only change boost by screwing on the bolt in the wg lid..

[S2central.net]

Dont forget the pump has to work harder to flow X amount of fuel when the rail pressure is higher (at boost)... You need to measure with voltmeter at fuel pump terminals.

In saying all that - could be that chips just arent asking for enough fuel - but more likely if its intermittent that it is related to flaky wiring / sensor.

If you arent making boost though it also smells of air leak and/or problems with boost control plumbing.

Would also say that 10.9 is unnecessarily rich unless you need extra fuel dumped in for a cooling effect... Much below 11.3-11.5 is wasteful IMHO and potentially sapping power... different tuners have different views of course and it depends on the application, fuel type, comp ratio etc etc

[x6rs]

so its mayde a good idea to change the wires to bigger ones? what voltage shpould i read at the pump?
going to investigate it tomorrow for sure, what sensors should i look at and where are they located?

i did pressurize the system and sprayed soap water everywhere to se bubbles, allt places except the hose fittings att the map-sensor in the box wich i couldnt reach.
no bubbles..

so now im going to try to make more boost by using a valve on the vauum hose on the wastegate.

[x6rs]

and yes i want a cooling effect by adding fuel, on track at wot the temps go up fast, not sure i can spank the engine fully lap after lap right now, last time i used the straights to cool it down, temperature went up to 100 degrees and beyond scary fast at wot, but shure i drive it really hard and rev it hard on track

[DJones]

so its mayde a good idea to change the wires to bigger ones? what voltage shpould i read at the pump?
going to investigate it tomorrow for sure, what sensors should i look at and where are they located?

i did pressurize the system and sprayed soap water everywhere to se bubbles, allt places except the hose fittings att the map-sensor in the box wich i couldnt reach.
no bubbles..

so now im going to try to make more boost by using a valve on the vauum hose on the wastegate.

You would be better off running it straight from the battery (fused) to the pump (given it sits virtually above it) and using the ECU signal wire to close the relay on cranking. I.e. all works as normal but wired directly to the battery..

If you apply 1bar of boost to the FPR put the return pipe in a bowl and crank it for 15 seconds, measure what you have and multiply it by four and it should be at least 2.5 litres..

Hope it helps.

Darren.

[S2central.net]

Ideally you want 0V drop between battery and fuel pump... Go with 2.0 or 2.5sqmm wire if you can - its normally a green/yellow wire on the H plug in the UR fusebox that you are interested in - if in doubt, buzz it out.

I would seriously air test *every* aspect of boost control on that machine before presenting the WG chamber with vacuum !!!!!!!!!

Have you checked that diaphragm is OK and bypass valve too ?

I just read your first post again - are you sure the chips are correct for that turbo and injectors cos if they are expecting bigger injectors for high boost running at 5000rpm then the RS2 injectors could be simply maxxing out and unable to provide the desired AFR... weird though that its intermittent. Impossible for me to 2nd guess anything - I only know what my stuff does, also with some enhancements to OBD code so I can log WTF is happening on things like that.

If I was you - would not drive that thing hard until problems are cured !

[x6rs]

is there a how-to guide how to do this somewhere?

thats a great and easy tip, i will try that tomorrow do i need to remove the coils when i crank it? 1 bar of boost, apply with an air compressor on the vaccuum hosa to the fpr i guess?

[S2central.net]

Just use a handpump 'mityvac' device on the FPR control port.

[S2central.net]

Oh and yes - look for a sticky post involving 'fuel pump testing' and 'hacktivator'

[S2central.net]

You would be better off running it straight from the battery (fused) to the pump (given it sits virtually above it) and using the ECU signal wire to close the relay on cranking. I.e. all works as normal but wired directly to the battery..
Darren.

Good advice there - only adjustment I would suggest to simplify things is to use the existing fuel pump feed wire to activate the local relay that is fed from the battery. This avoids the need to find the control wire from ECU into the factory fuel pump relay.