Snoopstah

<center><img src="http://www.alexisbirkill.com/lambda.gif"></center><p>Logged block 031. There's two fields in there, what am I looking at? Is the first the front lambda probe and the second the rear lambda probe? Or is the first the actual lambda value and the second the expected lambda value?

Anyway, it doesn't look quite right, whatever it is. The second value stays pretty smooth, although does fluctuate, but the first is all over the place! It never goes below 0, and the highest recorded was 0.93, but it's all spiky! The picture above shows the second value (green line) which is reasonably smooth, and the first value (red line) which definately isn't!

Any chance you could help me interpret this?

QCRAZY

You did a hard pull in one gear as discussed before I assume?? If so,.....

I'd say you found the problem...sort of!!

If you did a WOT run the second value is "close" to what you want to see. Both should have flattened out around 0.8-0.9V. The second is not *too* far off.

The first value is for the front o2 sensor. The second value is for the back o2 sensor.

Didn't they already replace the front sensor??

At this point I would say your first O2 sensor is shot OR your not getting fuel into the cylinders very well OR you have some bad fuel in the car.

However, considering that the second o2 sensor looks good, I would think it's just a bad first o2 sensor.

Hope this helps!!

Snoopstah

Hmmm, not entirely sure if it was WOT or not - busy roads today.

I'll try it again later, and also log the RPM.

They did change the front lambda sensor... :-(

Snoopstah

<center><img src="http://www.alexisbirkill.com/lambda2.gif"></center><p>Don't know what the heck I did last time, but it sure doesn't look like it was a WOT run!!

So I apologise for not reading your directions properly and wasting your time. I did another run, and the lambda values look fine. Plotted above against RPM in a run from stationary up to part way through fourth gear.

Just out of interest, when I'm *not* at WOT, why does the rear sensor stay reasonably sane but the front one jumps around all over the place?

Snoopstah

<center><img src="http://www.alexisbirkill.com/boost.gif"></center><p>Another graph for you to look at, sorry! This one logged at the same time as the lambda value graph I just posted, so full-out run from stationary up to part way through fourth gear.

From what I've gathered, the first boost value (blue line) is specified boost - is that right? So that gives a peak to start with, then fairly steady boost except during a gear change.

The second value, presumably the actual boost, does seem to waver a bit, but not a lot. Is this normal, or does it suggest that there may be a leak or I may have a knackered DV? I've noticed if I cruise along in third at around 5000rpm, then floor the accelerator, the car picks up, hesitates, picks up, hesitates, then goes. All that occurs in the space of about a second.

Also, another Just Out Of Interest question. I've noticed when driving along at a steady pace at say, 3000rpm in 5th, the spec boost is atmospheric (~1000mbar) but the actual boost is up at around 1300mbar. Don't I have a valve that stops the turbo spinning unnecessarily? An N75 valve or something?

Thank you (again!)

rickw

Supposed to do that in closed loop.

QCRAZY

Boost looks good. Yeah you got the actual and specified figured out.

That little spikes that you're seeing look like a bad DV, as you said. I would replace that and see if it helps anything. Also, get a DV from a Audi TT 225hp if you can. Little better valve.

N75 valve "runs" the wastegate. Generally the wategate won't start to open until you have a lot more boost. A little variance is normal but really 1000 to 1300 seems a little too much. Hmmm?

Try a new DV, see if that helps anything!

QCRAZY

Looks fine!