Rob in Oz

Not money, but fuel! I've been running a Guru chipset for the last couple of months and finally got the car onto a dyno with our local 928 Landshark group. Results on the dyno were pretty encouraging, except for the air/fuel ratio, which is extremely rich as soon as the boost comes on. Have a look at the attached dyno sheet - note - -it's in KW, not HP....where do I go from here?

Rob

OZ951

Yeah thats pretty rich, what capacity do you have to tune fuel (ie fuel controller)?

schadenfreude

Ahh... good to see another 951 owner in Brisbane! Where'd you get the dyno'ing done, out of interest?

turbo944

Are you running enough boost? More boost=more air=leaner mixture.... The Guru v8 chips that I have are designed for approximately 15-17psi boost. I'm sure I'm probably running a bit rich right now myself as I'm still running about 14 where I had been with the Autothority chips making sure I didn't get too lean in the upper rpms. I have my LM-1 from Stephen (Thanks Stephen!) and need to get the bung installed so I can start monitoring mine. However since I'm in the position of possibly changing exhausts very soon, I am looking at waiting just a bit longer to do install that so I don't have to do it twice.

Ski

Also remeber with the GURU chipset to get your FQS switch in the right position.

Dwayne Williams

Are you still running stock injectors and wastegate? Looks like you're not running enough boost. Are you using a reliaboost or some other boost controller? Do you have an aftermarket boost gauge or any other way to measure boost accurately? When I got my latest set of chips from Danno I was quite rich (worse than you) because I was running 15 PSI and the chips were programmed for 17 PSI. My choice to run less boost so I had to tune the maps and drop some fuel out in the upper ranges.

Waterguy

I would also go with not enough boost. 160.6 kW = 215 rwhp. That is about what a turbo S makes at stock 11 psi boost. Those ships be pretty close to 12.5:1 if they were run at 15 psi boost.

cpt_koolbeenz

What AFR values are ideal at x RPM, boost, etc? 14.5 idle 13mid boost 12high boost?

Rob in Oz

Guys

Thanks for your comments - but -

Boost was recorded during the dyno run and was 17psi at 3500rpm, tailing off to about 13 psi at 5,500rpm. This agrees well with my vdo gauge readings

All settings are as per Guru chipset instructions, w/g is shimmed, Reliaboost is installed. Guru FPR installed. FQS is at position #0

Injectors are stock

Only other mod is 3" cat back SS exhaust

Rob (Schadenfreude) - PM me re Brisbane stuff if you want to catch up

Wayne - no electronic controllers used

Thinking of going back to the stock FPR and re-running on dyno - unless Danno has any ideas....

Rob

jimbo1111

Check for intake leaks on the vacuum hoses and intake plumbing. Any leaks will make your mid soggy rich. Guru chip are leaner than most in that area.

Danno

Don't go to the stock FPR, because you'll end being too lean in the anti-lag zone around 2500-3500rpm. You might be a little too tean in the upper-RPMs., but your 13psi at redline is less than the 15psi I anticipated, so you'll right around 12:0 which is OK.

The issue here is the 17psi extra boost I think. It causes the rich spot right as it hits because the extra boost increase the fuel-pressure on the FPR. I'll get you the latest version 18psi chip and you'll be fine. It'll take about a week to get down there..

Rob in Oz

Danno

Thanks for that - I'll look forward to trying another chip. i'll dyno it and let you know how it goes.

Rob