VX-VY V6 Flash Tuning

[Tre-Cool]

So, out of boredom and because i thought why not. I've started to play around with my daily v6 shitter.

It's a factory duel fuel car, now running e85 instead of pulp. Picked it up for around 2 grand with 360K km's on it, had to put a new set of plugs, injectors and clean the maf for it to run properly but i've done 8k km's in the last 12 months in it getting to the airport (used to do fifo) and general run around duties while the v8's were off the road or getting worked on.

Anyway enough of the bullshit, i'll get onto what im in need of & that's advice on the v6 side of things (i've used efilive for over 10yrs).

Couple of questions first if anyone can answer.

1)Does the VX-VY ecu have a VE table or is it magically calculated off a base figure somewhere and the maf/injector flow rate tables do the rest?
2) How do you keep the ecu in open loop to adjust fuelling so that open loop doesn't interfere
3) How is Airflow calculated. TP5 logs G/Sec, but tune has mg and something else. At the moment i'm taking guesses at the spark map/injector multipler and getting good results.
4) Trans question, are the force motor calibration tables correct & are the numbers inputted as PSI for the required TPS & VSS, i've had a play and compared to the v8 stuff the pressures seem very low.

The reason for asking the first 2 questions is, I purchased supposably stock in injectors and the car ran pretty much fine with the switch to e85 as ecu was doing it's job in closed loop, however pe was attrociously lean.

So far I've managed to get reasonably close stoich idle before it switches to CL but i've had to use the injector multiplier in a big way (i think i have maxed it out at 1.3) for the higher rpm/high load area's and only just getting down to .90 lambda at wot. (I have a dyno in the shed..) Powerwise it's gone from around 120rwhp to repeatable 139.x's on fuel and slightly less on LPG, however i haven't played with lpg timing yet.

LPG doesn't seemed to be affected by injector manipulation, but I'm not sure if there is any feedback to the lpg system from the ecu?

[VL400]

1)Does the VX-VY ecu have a VE table or is it magically calculated off a base figure somewhere and the maf/injector flow rate tables do the rest?

Being MAF (Mass Air Flow) based it can measure the air mass to inject the correct amount of fuel. More info on them here .. http://en.wikipedia.org/wiki/Mass_flow_sensor

2) How do you keep the ecu in open loop to adjust fuelling so that open loop doesn't interfere

One way is to change the minimum closed loop temp to something hotter than it will ever run.

The reason for asking the first 2 questions is, I purchased supposably stock in injectors and the car ran pretty much fine with the switch to e85 as ecu was doing it's job in closed loop, however pe was attrociously lean.

So far I've managed to get reasonably close stoich idle before it switches to CL but i've had to use the injector multiplier in a big way (i think i have maxed it out at 1.3) for the higher rpm/high load area's and only just getting down to .90 lambda at wot. (I have a dyno in the shed..) Powerwise it's gone from around 120rwhp to repeatable 139.x's on fuel and slightly less on LPG, however i haven't played with lpg timing yet.

E85 and unleaded have very different stoich values. You will need to adjust the target AFRs to suit the E85 stoich of about 9.76 (it changes with different ethanol contents).

[Tre-Cool]

1)Does the VX-VY ecu have a VE table or is it magically calculated off a base figure somewhere and the maf/injector flow rate tables do the rest?

Being MAF (Mass Air Flow) based it can measure the air mass to inject the correct amount of fuel. More info on them here .. http://en.wikipedia.org/wiki/Mass_flow_sensor

2) How do you keep the ecu in open loop to adjust fuelling so that open loop doesn't interfere

One way is to change the minimum closed loop temp to something hotter than it will ever run.

The reason for asking the first 2 questions is, I purchased supposably stock in injectors and the car ran pretty much fine with the switch to e85 as ecu was doing it's job in closed loop, however pe was attrociously lean.

So far I've managed to get reasonably close stoich idle before it switches to CL but i've had to use the injector multiplier in a big way (i think i have maxed it out at 1.3) for the higher rpm/high load area's and only just getting down to .90 lambda at wot. (I have a dyno in the shed..) Powerwise it's gone from around 120rwhp to repeatable 139.x's on fuel and slightly less on LPG, however i haven't played with lpg timing yet.

E85 and unleaded have very different stoich values. You will need to adjust the target AFRs to suit the E85 stoich of about 9.76 (it changes with different ethanol contents).

Cheers, I'll have to take another look for the CL temp setting and have more of a play on the weekend.

i realise the stoich level changes with the fuel, but i've left it at 14.76 as i figure there's not much point changing it as all the other tables are still set for the correct fuel mixtures (there essentially all multipliers) & the o2 sensors will allways switch at stoich (lambda 1) no matter what fuel is used. I've used the same theory on the later model E38's that have inj flow rate limitations to maximise spark map resolution.

[Holden202T]

how is that going to work in open loop though ?

i've found with the speed denisty system the only way to really get a good working system on methanol/e85 etc is to change ALL attributes to suit the fuel your actually using.

[Tre-Cool]

My primary reason for wanting to switch to open loop is to see if i can get some more adjustment out of the fuelling side of things & manipulation of the maf table's is my next step.

I found that even with the stock tune, prior to closed loop kicking in the engine was running about 0.68 λ (10.0afr if it were petrol) at idle when commanded afr was 14.12. Remember this is coming from the wideband on a Dyno dynamics machine, and a switch to lpg would bring it instantly back to 1.00 λ idle.

I think my issue seems to stem from the injectors i placed in the car which were supposed to be identical to what i took out, but they are physically different so i think they are bigger than what is needed. The original injectors were a bit more fat/stubby where as the ones i have in it are more slimline like ls1 injectors.

[antus]

Yeah, if its not the same part number then you need to adjust flow and voltage compensation from manufacturer data on the new part. Trying to find replacement ls1 injectors recently, I found there is a hell of a lot of misinformation out there and many claims of direct swap injectors are just not true. Even comparisons of flow rate dont tell the whole story when different fuel pressure is involved.

[EagleMark]

I found that even with the stock tune, prior to closed loop kicking in the engine was running about 0.68 λ (10.0afr if it were petrol) at idle when commanded afr was 14.12. Remember this is coming from the wideband on a Dyno dynamics machine, and a switch to lpg would bring it instantly back to 1.00 λ idle.

As you have found the Stoich AFR for the petrol you have is not 14.68, but 14.13. Which is accurate for petrol with 10% ethenol as we have here in US.
"Stoich for gas is 14.7 AFR. Stoich for Ethanol is ~9.00AFR. That means that Stoich for E10 would be (14.7 x 0.90) + (9.00 x 0.10) = 14.13AFR."

Yes the narrow Band O2 sensor will adjust to stoich/Lambda but fuel trims are off/not 0! If you set Desired AFR or Stoich to 14.13 instead of 14.68-73 then your fueling calculations are closer and tuning is easier/correct, not fudged in VE to make calculation correct.

[darcy]

Dave,

The simplest solution for a fuel change would be just to change the injector constant to account for the different stoich value.
Then leave the AFR definition as it is.

I've also redefined the Open Loop AFR, Lean AFR & PE to display as EQR to try and keep my head straight when swapping from EFIL to TP.

darcy

[Tre-Cool]

Dave,

The simplest solution for a fuel change would be just to change the injector constant to account for the different stoich value.
Then leave the AFR definition as it is.

I've also redefined the Open Loop AFR, Lean AFR & PE to display as EQR to try and keep my head straight when swapping from EFIL to TP.

darcy

yeah that's what i've been doing, modifying the "base Injector Rate" but i suspect the injectors are bigger than what it needs because even on petrol it was rich.

i'll have another play on the dyno tomorrow after i've finished another car. (v8 = simple)