I've just got back from Powerstation (see the thread in Rolling Roads). But the guys weren't able to complete a power run for me as the car was running lean as the turbo started to spool up (2.3-3k). The reading dropped from 0.8 to 1.0 by those revs.

The strange thing is that the car has been in its current setup for well over a year now In that time, I've been on track days and enjoyed 'spirited' driving, so I'm suprised it hasn't gone bang before now It seems that my first rolling road was very timely!

(Current tune is: Standard turbo, Gtec1, PA FMIC, SIP, Blitz @ 1.2bar, Stainless Catback).

Speaking to the guys there and Paul @ Motormech on the way home, the best guess is that something has recently started to fail, such as the fuel pump, or a leak has started somewhere.

I was planning to uprate the fuel pump + wiring mod anyway. And I was also planning to move up to a Gtec2. I'll get Paul to check it over for leaks when he fits the fuel pump.

Any other ideas what might be causing this?

(We've ruled out the MAF sensor, as the car idles fine).

Thanks

Air leak after the maf but before the turbo. All the ancilliary hoses still properly attached to the SIP?

Were they able to check the fuelling at the top end?

You're running a CAT - so where did they take the fuelling reading from? Pre-or post CAT?

I dont understand this reading - can you clarify pls?

Sorry to hear that Dave. When I've been there before they refused full power runs on a couple of coops. One of them was forum members Maxxers. I'm not sure what was wrong in the end but they described it as "stupidly lean".

Suba - They use a wideband lambda up the tailpipe and a voltage readout in the testers hand. I think lambda 1v = very lean.

Looks like you'll need another trip then Dave. McMike and I have Monday 3rd Dec in our diaries.

James

Basically they use lambda instead of AFR therefore a reading of 1 is 14.7!!! A 0.8 is around 11.8 AFR so you were doing ok until it leaned out to a dangerous level just when it is most likely to det.

How do you get an accurate reading from doing that - it's after the CAT surely?

Link to a motec page with lambda reading to a/f ratio conversion table;

http://www.mrtrally.com.au/performance/docs/Lambda%20Brochure.pdf

This is an extract of the info;

Lambda......A/f ratio (petrol)
0.70.......10.3
0.75.......11.0
0.80.......11.8
0.85.......12.5
0.90.......13.2
0.95.......14.0
1.00.......14.7
1.05.......15.4
1.10.......16.2
1.15.......16.9
1.20.......17.6
1.25.......18.4
1.30.......19.1
1.35.......19.8
1.40.......20.6
1.45.......21.3
1.50.......22.1
1.55.......22.8
1.60.......23.5

So it looks like they consider 14.7 (Stoch) to be too lean for an on-boost turbochargd car.

James

You beat me to it Flea.

James

Cleaned your airmass meter recently? Important if you got K&N-filter or such.

Wouldnt that cause it to run rich, as the MAF has already seen the air, but its missing from the mixture?

Ross

Never mind.

Im asleep today...

Ross

Thanks for all the responses ... much appreciated

Matt, yes all hoses are still properly attached on the SIP, but I'll get Paul to check for any other leaks as well.

Suba, I think Flea and Jap have answered the q over 0.8 to 1.0. And Powerstation simply weren't happy with running it at that level This has hopefully saved my engine though (touch wood!)

Per, no I haven't cleaned the MAF. Its a good point - I used to run a K&N which could have dirtied it. I have had an Apexi/SIP on for over a year now though. I'll get it all cleaned up though, just to make sure.

You really want the car to be running in the 11's - but you can run a bit lean coming on boost to help spool I believe. If you have had the car on track I very much doubt you're running into the 14's at the top end without problems...?

Suba, yes it was interesting that they thought twice about cheesy's run to. As it spooled up, his was hitting the very-low 0.9s, but they were happy to push through that and the top end fuelling was ok.

James, Flea
Sorry - I completely forgot to reply to your posts Thanks for the thoughts. I'll not be able to make 3 Dec, James, as I'll probbaly go down before then to get all this sorted before the planned track day on 25 Nov at Donington