Urs4 running lean . Lambda, MAF, pressurer regulator?

[Isaksa]

I do have one :-)

Mabye i have to fit a hose, and get the gauge inside the car and check If anything happens when i am gjetting boost.

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[Isaksa]

Lokking in the wiring diagrams to find out how to hackstart fuelpump. Any idea?
Then i will run for 15 sec

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[S2central.net]

Search the forum for "hacktivator" ;-)

Do not run fuel gauge inside car - you can test it with pump running and mityvac hand pump attached to control port on the regulator.

[Thuppu]

Or put the gauge under your windscreen viper and secure it with some tape.

[S2central.net]

Seen some drag machines with big fuel pressure gauge visible through the window - only way to bring the gauge inside is if it is the expensive type with electrical connection thru bulkhead to a pressure sensor in the engine bay.

[S2central.net]

http://www.s2forum.com/forum/showthread.php?t=52979&highlight=hacktivator

[Isaksa]

I have tried to find out If the fuel pressure rises when boosting..
So, Iv'e mounted my Gopro camera and a Flashlight under the bonet, and streamed live on my mobile while driving to work this evening.
I was charging 1.5 bar for about 2-3 sec and could see on the fuel pressure gauge that pressure rises from 4.8bar to aprox 6 bar. AFR starting to bounce, but stays between 14-15.7
Can i erase the fpr off the list?

Tomorrow i will hack the fuelpump and check Flow for 15sec.

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[S2central.net]

Very innovative solution for remote viewing there but you don't a clear view how stable it is - get a mityvac or similar and play with the control port to see it rising and falling consistently.

[slow2]

I will make a leaktester unit at work tonight, fitting where the MAF usaly stands. anyone remember the diameter of the valve that all you guys have in your tires?

I dont think you need to worry about boost leaks at the momment,
as you say you see 1.8 bar boost regularly and your problems are to do with being too lean (under fueling),
if you had a boost leak your problems would be too rich (over fueling)
so i think you do need to check all fuel supply/delivery components.

[Sleeper_Avant]

why hasnt anyone commented on the missing electrode from the spark plug????????

come on lads,

if its done an inlet valve when it melted the plug why do you think the AFR`s are bad?

this is basic mechanical stuff here

Problem, Evidence, Diagnosis, Repair

[newsh]

Still worth pressure testing, could be a leak before the turbo or in the PCV system.

Where are you seeing a missing electrode Sean?

[S2central.net]

why hasnt anyone commented on the missing electrode from the spark plug????????

come on lads,

if its done an inlet valve when it melted the plug why do you think the AFR`s are bad?

this is basic mechanical stuff here

Problem, Evidence, Diagnosis, Repair

What photo shows the damaged plug ?
I can see how lean running and high resulting burn temp could do such damage to a plug or even some valves but I dont see those as root of the problem - the mixture is too lean under boost but it used to be ok.

[Isaksa]

There is no missing electrode.
Only a bad photographer ^_^

I have tried disconnect MAF when idling, and the engine starting to run bad. So it is working ( at least when idling)

Now i am Just thinking If i am at WOT, the load % in vagcom should be 100%
What If it's only showing 60% at wot.. Then the engine will get more air than ECU know. Is there any possibillity that the MAF is working at idle, but not under load?

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[S2central.net]

The load reading won't tell much from OBD as all that stuff lines up with factory sized MAF housing.
What would be good is to monitor the voltage from MAF and see it is broadly linear with the amount of air flowing thru it - a proper flow bench is needed to do that accurately but driving with flat boost across rising revs will show something... If it doesn't deliver high enough value at full boost then you won't get enough fuel.

Remember boost is mapped from throttle position but mixture and timing is mapped from MAF. It would have been good if the guy that mapped it on the custom MAF pipe made some voltage measurement when engine was running correct mixture at boost.

Anybody nearby have a MAF you can swap for comparison ?

[slow2]

Hello!

My URS4 is running lean when boosting.
I am using rs2 maf in 4" pipe, "bosch green 0280155968" 440cc injectors with 4,85bar fuelpressure (turbosmart fpr800) with vacuum of.

I have an average between 14.6-14.9 in air fuel ratio at idle/slow traffic.
Earlier when boosting (1.8bar) i had afr readings down to 11.8, witch is right i supose.
Now i don't get less than 14.0 afr when boosting. This can't be good, so i am not using my car until i have fixed the problem..

What can cause it running lean ?
Lambda, Maf? Fuelpressure regulaor?

It looks like your car/ecu is holding everything togther in lambda close loop (idle/part thottle) mode and as mentioned by S2central.net "the ecu comes out of closed-loop mode under full throttle and the mixture you get is what is programmed in the maps for the relevant engine speed and load point"
i think we can presume your map was ok for your set up before this problem came along, so I still think you should be checking fuel delivery is ok, a good starting point is a new fuel filter, its not too difficult to do and a faily cheap price to rule out 1 of the possible faults before looking deeper.