S6 timing

[prj]

He needs to measure fuel pressure while on a WOT run and see what it is doing.
That will tell whether it's a fuel delivery problem or it isn't.

That said, if load is 140 at WOT, that seems low as well.

[HMS-S6]

I'll check the fuel pressure Monday first as Dmitri suggests And see what it says, God knows there to go then but o think it'll involve giving Dmitri some money when he can fit me in. Haha.

[newsh]

Posted a million times, but RL = KFUN(maf)/RPM

Dmitri, do you think this is a fuel delivery problem?

[prj]

Posted a million times, but RL = KFUN(maf)/RPM

[twoqu]

What is the significance of the load figures quoted? Is that a measurement of air through the maf? So if it should be in the 180 region and he has got 140 does that imply unmetered air?

[prj]

Mixture lean at WOT = your theory is useless, sorry.

[twoqu]

At least that 00561 code is confirming a lean mixture even at idle which means presumably the closed loop cannot add enough fuel.
There have been cases where the throttle body spindle leaks but mysteriously seals up when under boost. I have never seen one dismantled but as such I understand that there are no seals as such but just bearings. This type of fault might allow the ingress of unmetered air until the boost pressure (or pressure test) reseats something.
This fits with our its on the car theory and how unmetered air gets in and how it does not leak out again at certain boost levels. I was struggling to work out how it was possible to get unmetered air in without its showing as a leak when pressure testing testing. However if you are leak testing it with say 1 bar that might be sufficient for it to seal back up giving a false positive. Perhaps if you can supply it with less pressure during testing it might expose it.
Discuss!

http://www.s2forum.com/forum/showthread.php?t=53164&highlight=throttle+body

[HMS-S6]

It's ordered now anyway so we'll see what it says on Monday I guess :-s

[prj]

Strongly suggest that you NOT run a mechanical fuel pressure gauge into the passenger compartment. Suggest that you run an electronic fuel pressure gauge with a fuel pressure transducer/sender, such as this one: http://www.glowshiftdirect.com/white...ure-gauge.aspx

Disagree, we do this all the time, as long as everything is high quality with AN fittings it is just as safe or even safer than the fuel lines in your car.

[HMS-S6]

Been driving it all day today, not really diagnosing it but typically man style last minute Christmas shopping! But I did notice one thing. Whether it's significant or not I have no idea; if I went into a shop today for, say, half hour, when I came out and got in it, it was noticeable better for five minutes or so (or the first 2nd gear WOT). Just thought I'd throw it out there!

[HMS-S6]

I've never even seen them. Just ordered a 'stack' set up. Should be here Monday.

When studying it today, regardless of boost level (stock OR mapped ECU) at WOT the AFR was set at 14:1. I was expecting it to run leaner and leaner when more boost is applied but seems it's at 14:1 regardless, right from 1 bar to 1.5

[UrS4boy]

C4 Fuel lines: From the tank to the engine and back again.

I am. I'm going to do the filter thing Dave said anyway and then I'm going to run a line into the car somehow so I can have it in the car with me. Not terribly 'health and safety' I know but hey ho!

Strongly suggest that you NOT run a mechanical fuel pressure gauge into the passenger compartment. Suggest that you run an electronic fuel pressure gauge with a fuel pressure transducer/sender, such as this one: http://www.glowshiftdirect.com/white...ure-gauge.aspx

Also with regard to the fuel smell, it's only with the car running.

That suggests that there is a fuel line leak, perhaps at the top of the tank, or one of the lines leading to/from the engine compartment.

C4 UrS fuel line info: http://forums.quattroworld.com/s4s6/msgs/226410.phtml

[newsh]

I guess you could run it up the road with the fuel cap undone to check it isn't vacuum in the tank..

[driftin jo]

it has a none return valve IIRC

[andy10v]

Does the stock fuel pump have a pressure relief valve that can play up?