Can these boost logs be right?

[Shoppinit]

My car feels down on power. These are the logs from my power runs. Boost seems late, but I have nothing to compare it to. Any thoughts? Thanks.

BOOST vs RPM:
http://img114.imageshack.us/img114/7744/boostlog2.jpg

BOOST vs TIME:
http://img237.imageshack.us/img237/918/boostlog.jpg

[DHall1]

need specs on your car.

what has been modified and where are you located?

[Shoppinit]

Sorry. Car is 100% stock. Located in Europe. Running 98 RON octane

[DHall1]

Which gear is this pull made from?

The question is...

Should a stock RS6 take 1500 rpm to reach full boost at or around 4000 rpm?

Right?

We need to search for some stock logs. Anyone have some handy

[Shoppinit]

The first graph would be in second gear, so I was trundling along in 2nd at 2500rpm and the turbo should have been ready to go.

The 2nd graph is full on acceleration in 1st after gently accelerating to about 2500rpm. You can see the gear change to 2nd. Seems like the revs drop a lot, but maybe this is normal.

Tests done in tiptro mode.

[Shoppinit]

So, yes, that is the question. I would have thought that I'd achieve specified boost before 4500rpm.

I tested acceleration with my g-tech and vagcom, and I'm pulling about 5.5s 0-60 at best, with 30-70 times of about 4.2 / 4.4s. The latter sounds OK, the former sounds (and feels) slow. I'm also getting some slight hesitation under WOT.

[DHall1]

You could have a slight boost leak.

Try a pull in 3rd gear to compare.

Then look at the N75 and diverters.

How many miles on the car

[Shoppinit]

Thanks. What will a pull in 3rd show? I'm quite happy to try that, I'll just need to find some more road :)

I was thinking of changing the N75 and DVs because they are so cheap. I don't want to play "changing random parts until problem resolved" for too long though, because after that it gets expensive.

Car has about 75000 miles on it and is in good condition. No DTCs anywhere.

[DHall1]

Boost builds faster in higher gears.

So we could compare 1,2 and 3rd gear pulls.

You dont need to go far...just up to 5000rpm is fine.

Then lets take another look.




Thanks. What will a pull in 3rd show? I'm quite happy to try that, I'll just need to find some more road :)

I was thinking of changing the N75 and DVs because they are so cheap. I don't want to play "changing random parts until problem resolved" for too long though, because after that it gets expensive.

[Shoppinit]

Sounds good. I'd really like to see some boost logs of a known healthy car to know if I'm worrying about nothing, though.

[Hy Octane]

There are some hoses under the top engine cover that due to the extreme heat of the motor dry out and crack. I had all of them replaced recently and the car is running like new.. Before, it was erratic and surged .. Also check MAF's and transmission as possible culprits..

[snoopra]

Isn't there another valve that controls the N75 which is sometimes the culprit for erratic power? It's a 200 valve, N2**?

[snoopra]

There are some hoses under the top engine cover that due to the extreme heat of the motor dry out and crack. I had all of them replaced recently and the car is running like new....
Did you use OEM or silicone for the replacement hoses? Where did you get yours? I bought some blue silicone, but the hose running to the boost gauge collaspes while idling.

[Shoppinit]

Isn't there another valve that controls the N75 which is sometimes the culprit for erratic power? It's a 200 valve, N2**?
Are you thinking of N249?

[dmross]

Are you thinking of N249?

The N249 controls the diverter valves according to the study guide in the sticky. I read in another thread that there is a simple diagnostic to check the solenoid functionality in VAG-COM, maybe search for N249.

[snoopra]

That's the one! Can it fail w/o throwing a code?

[Shoppinit]

Yes, it can fail. There are many components that can fail with throwing a code. It depends how the self diagnostics are carried out. The DVs that the N249 control tend to be more failure prone since they rely on a diaphragm which ages badly.

dmross: There are some people who bypass the N249 and drive the DVs directly from manifold vacuum. I don't think I'd be comfortable doing this with the RS6 though. There is an AUdi procedure for testing it, resistance across contacts, etc.

[Hy Octane]

Did you use OEM or silicone for the replacement hoses? Where did you get yours? I bought some blue silicone, but the hose running to the boost gauge collaspes while idling.

Was replaced under warranty so it was OEM..