Disappointing Dyno Result

[Sonic]

Interesting looking at the boost graph on the n-stream run (the one that made the most hp). Less boost, more power

[Sonic]

WG spring pressure at redline is not 0.6 bar, it's ~0.3 if setup correctly, dropping from ~0.4 at WG crack. I've done some testing on the standard spring and a stock turbo car.

Yeah that's right, if i switch on the "valet mode" so it just runs off the WG spring and doesn't go above ~0.3 bar.

[UrS4boy]

F96 Altitude Sensor Info

F96 Altitude Sensor info:

http://forums.quattroworld.com/s4s6/msgs/21892.phtml

[Rusty]

Trying to get an output graph for the sensor but seems like anything below 4V output is getting on the low side. mkay.

http://www.sjmautotechnik.com/trouble_shooting/20valt.html

There's some info on s2central.net, it looks like the stock ECU can drop up to 0.4 bar of boost.

Really you could do with some VAG Com love on it Sonique, that should help identify anything that's not reading correctly.

[Sonic]

Really you could do with some VAG Com love on it Sonique, that should help identify anything that's not reading correctly.

Oh god, not again

I've got vag-com, just can't figure out how to use it besides looking at fault codes.

[S2central.net]

If its not hitting target boost, there are four main causes to look into -

1 - Air leak - unlikely if lambda looks OK
2 - Throttle position sensor - or its connector - ECU has to see full throttle input before it requests maximum boost
3 - WGFV - could be lazy, or maybe the WG itself has too much creep
4 - MAF related problem - pesky connector issues maybe

Beyond that - wonder if there is knock (or likely some other noise the ECU hears as knock) which then pulls timing and boost back - but never raises a fault code as is the norm unfortunately.

The car was flying nicely before so something silly is wrong... Finally - have you checked the spark plugs are all at 30Nm ?

I would do a compression test as well to rule out anything potentially nasty like a head gasket problem.

[S2central.net]

Oh god, not again

I've got vag-com, just can't figure out how to use it besides looking at fault codes.

@Sonic - if you can run this website - you can operate VAGCOM

The biggest problem is that the ECU doesn't throw up many errors unless it detects things that are open or short circuit. For example if you have a water temp sensor that is out of spec - you will not get a fault code.

If you go into 'measuring blocks' on a warm idle - tell us the 10 figures from Group 0

The other groups are labelled with RPM, Temp etc so you can spot if something like a water temp or air temp sensor is out of spec.

[Sonic]

Cheers guys

@Sonic - if you can run this website - you can operate VAGCOM

I can now

http://www.s2central.net/vagcom_4.html

I'll have a look at some of the values and post what i see, cheers Paul.

(On a side note, you need to take s2central out of frames so it's easier to link to specific pages )

[S2central.net]

(On a side note, you need to take s2central out of frames so it's easier to link to specific pages )

I know, but I'll do that someday I am more busy

[S2central.net]

Group 4 is a good one to watch during a WOT run - check the ECU is seeing WOT

[Sonic]

Knowing i can log a few channels at a time, i'm going to have fun with this now

[Sonic]

Just to confirm that the lambda graph is correct then, starting at ~1 and dropping to ~0.8 as the turbo kicks in?

The dyno guy said this indicated it was running lean.

[S2central.net]

Lambda of 0.8 means 0.8 * 14.7 in terms of AFR which is ~12 and therefore about right.... running towards rich as boost picks up.

If you see lambda values above 1 at WOT then you are running lean - remember the Motronic ECU cannot adapt mixture during WOT - it runs directly off map values which should ideally have some margin for richness to protect for aging effects like clogged fuel filters, weak fuel pumps etc. But thats detail.

[EspenW]

I would not pay too much attention to the lambda signal at WOT since this is from a narrowband sensor.

Now that you have mastered Vagcom, you can log the time it takes from 4200-6500rpm at WOT in 3rd gear and use this to compare the time to a vast number of times from B5 S4 and RS4's.
Use this before/after mods, etc.

[4WheelDrifter]

It does look a bit like knock at 2800 rpm.