AFR surge @ 80 to 100kph @ cruise & cruise control enabled

[Grim Reaper]

Attention Bill, and Tuners of Australia

We are currently in the process of developing & testing a factory standard 2008 FG falcon xr6 turbo 6 speed automatic with only 60ib Injectors, Racecraft cooling system Mod & the aid of hp tuners/Vcm suite.

All our WOT tuning EG,Boost curve,IG curve,Afr with the 60ib injectors has been completed on a chassis dyno.

Im having a problem at anywhere between 80 to 100kph, 18 to 21 % throttle @ cruise or with cruise control on, the Air fuel ratio fluctuates between 14.5 to 13.6.Prior to fitting 60ib injectors AFR fluctuation still occurred @ cruise.

I have logged data via a fuel base vs rpm vs tps pid on the scanner and highlighted the cells were fluctuation occurs and noticed a 14.5 afr reading although it doesn't read the 13.6 afr drop in the scanner cells.

I inspected the fuel base table in the editor and the Lambda reading is 1.0 four cells across and 4 cells down which is standard lambda readings.

I've also checked the cold fuel base tables in relation to our cruising cooling system temps Lambda is 1.0 four cells up and four cells across.

I've tried to remove several provisions in relation to cruise although I have been unsuccessful.

Just came back from a road test and thought id update towards what I have found.

Ive nailed it down to being the STFT to be correcting the AFR for some reason @ cruise. I've tried to remove closed loop correction by increasing the closed loop 02 sensor Temperatures so that closed loop would not come on.

Also increased the numbers closed loop delay vs start up ECT and switched off LTFT learning switch.

With the cruise control set @ 80 and 100kph the AFR is perfect and holds a constant 14.6 AFR no fluctuation. 4.5minutes driving the vehicle the STFT start to correct the AFR, Then a wave form of fluctuations from 14.6 to 13.9 AFR Occurs.

If anybody could shed some light on the surging problem i'm having that would be great.

Regards

[JETURBO]

Check your scalers for 60's as many have this wrong

Use livelink to check your LTFT on a long hot idle condition

Don't use hp for any logging at all on a falcon

Remember its load based so even at 21% throttle u may break into a load condition requesting a richer lambda...... Say. Incline in the road condition .....

[Grim Reaper]

Thanks for a reply JETURBO.

SCALERS?? Are you referring to LTFT & STFT??

I can log STFT & LTFT on the HP scanner, Whats happening is the stft are trying to correct themselves by adding fuel hence why The AFR changes on the stft scale its +6, Ive also logged it on a Snap on scanner although snap on does not give me STFT. Is there a problem with HP for logging STFT & LTFT with your experience??

Ive logged the Percentage of load when the fluctuation occurs @ cruise anywhere between 37% to 41% Load... Is there a way to Line up the STFT & LTFT within 2% of each other on closed loop??

Ill check out this live link Jeturbo

[JETURBO]

You really need livelink to log , thats step 1

And it sounds like your just in and out of load points that are requesting richer/leaner lambda

If u have a vac/boost guage watch it move all over the place and this will show simular to what the "load" value would be doing and yes even on cruise conditions

Scalers are your hi/low slopes then the offsets/breakpoint/PW and then the modifiers all play a part, a very clear base on what the falcon was factory tuned to do needs to be learnt before anyone starts playing with a new tune and lots and lots of logging and "looking" whats happening and why to get a clear indication of what u want to be doing when u start changing tunes, but that being said if ur getting 14.7 your at least close enough to 1.0 and scalers that are useable so far

The fact you have said the issue was there previous to fitting the injectors and the fact the low load scale of afr was left untouched id definately lean towards your bumping into a higher load scale requesting richer afr as per factory tune and the obvious reason for this

So if this is the case everythings fine, but you will only tell if LTFT are out is with a steady load point ( idle )

[Eric@HPTuners]

Gonna have to have a log to help you with this.