How to tune A/F Ratio on Alloytech Engines?

[BigDaddyCool]

Can someone please explain to me how to tune air to fuel ratios off this tune file.

It's from a 2006 Holden Commodore (VZ Executive) 3.6ltr v6.

I've been logging via VCM Suite ...... reducing spark to reduce the knock etc...... and then adjusting the fuel via the stft and the ltft's via adding/minusing from the fuel injector multi.

People keep asking me what A/F Ratio I run for stuff......... and I have no idea how this works. Most tunes have an area for it, mine doesn't.

Can someone please explain this for me for my "specific" tune file....... not refer me to some V8 thread that has zero meaning to my alloytech engine setup.

Cheers
Jamie

PS. I have a narrowband guage only on the car, as I see no point for a wideband obviously cause there is no A/F Ratio in my tune???

I measure via STFT and LTFT. My car has 2 stock widebands before my cats, 2 narrowbands after my cats.... So it's pretty accurate with the STFT etc

[Shane Hewitt]

Under Fuel Control>Power Enrichement you'll see a tab Lambda. This is where your PE air/fuel ratio is controlled (Stoich * Lambda = air/fuel ratio)

[BigDaddyCool]

Yeh I see that........ but I dont understand.

Mine runs from 70-100% "driver demand torque" axes....... vs rpm.

I figured this was for above 70% throttle?.... I may sound stupid saying that, but that's how I thought it worked.

So between 70% to 94% I have a 1.0, so is 1.0 stoich....... and if so how do I know what air/fuel ratio that is....... eg 14.38 etc.

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Do you know what I mean?......

70-94% = 1.0
95 & 100 = 0.86

So how do those valves effect the overall fueling from idle to however I drive the car etc?

[BigDaddyCool]

In essence as a follow up question.

If I want to lean out my highway cruise, your essentially saying I can through the power enrichment table.

So if I'm crusing at 2000rpm to 2100rpm.... how to I lean it out a bit using that table then? do I change one of the values to 1.01? at the rpm range.

Whats the drive demand torque, how does that work?

[Nev1]

air flow, torque based. Max VE flow.

[BigDaddyCool]

Yeh I figured it had to do with the airflow demand......... and noticed the VE seems to effect the general fueling.

But how exactly do I work out how the Air-to-Fuel ratio works out across the airflow demand table etc......

[Nev1]

a higher number in that table makes it richer. I struggled for ages with the engine being dead as a turd at 1600rpm to 1900rpm.Sounds silly, but thats where one drives a lot unless on the open road. The ign would pull out spark at those rpm and make the car run flat. It was too lean there, when I added fuel, I could add more ign and the engine is now lively and more responsive.

[BigDaddyCool]

Yeh it certainly does change fueling there, I noticed even 0.02 seems to make it somewhat richer. Correct me if i'm wrong tho all it mostly does it remove a tad of torque in that area to add the extra fuel?.....

Either way it does work yes. So I'm guessing I can use this same area to smooth out my highway cruise which sits at around 2050rpm at 15% throttle.

I seem to knock in this area even with stock settings.

It makes it extremely difficult to edit the spark area because the 4 spark tables dont really correspond with how they work.

Like on the alloytech it's like 2 cold tables, 2 warm tables....... iat max, exhaust max etc. But really we dunno what temps goto what table.

So when it knocks and I need to adjust my spark down, which table do I go for? .... even with the stock spark table if u throw torque upto 100% in the normal area's the normal table knocks.

I really wished there was a better way to determine what spark table the vcm scanner is showing.

[Nev1]

I guess I could say "read the instructions" but there is none. :-). I found the way to find out what spark is where is to make an air load gauge in your scanner. You will need the beta version of the software for this. There are about 4 or 5 things that effect the spark. Is yours one with variable exh cam timing as well or just variable inlet cam? Mine is the 175kw version with inlet only.

[BigDaddyCool]

mines the 175, just the inlets....

[Nev1]

I put the hot cam timing tables into the cold ones. Engine runs better and timing is more consistent. Apparently the cats do not heat up as quick... who cares.. :-)

[BigDaddyCool]

ok back on topic tho, you were saying there was a air load gauge u've made for the scanner?.... infos

[Nev1]

reread, you need the beta software. Then you can do an air load gauge for the scanner and the tuning will make sense more. % load is on some axis of the tables in the HP tuner. Throttle position is in other tables,it is not the same.

[driftnpow]

Hmmmmm guys suggest you stick with the principle of "KISS"....
You want to fine tune fueling... the alloytecs at present your stuck with 14.7:1 AFR (stoich)/lambda of 1
the o2s are going to force that all the time in closed loop - eg, fuel trim readings. alter your fueling constants and multipliers + maf to bring this as close to 0% FT correction and you should find knock will reduce, engine will run smoother, starting and idle will stabilise and easier to maintain.
as for PE-Power Enrich this is a lambda based table for commanding that little extra fuel needed for power when needed eg. WOT

As for using a "hot" cam timing table when the engine is cold, not recommended this will only help but accelerate wear as advanced airflows will blow out heat the heat needed for rapid engine heating at startup, have similar but not so dramatic effect as having a thermostat jammed open.
On the subject of cams they can alter the AFR... but suggest keep with the basics first before moving onto more technical stuff!

[Nev1]

I have had about 30 cars and over 55 motorbikes, all of them others seemed to run just fine with the same cam timing when hot or cold.So does this one. The ign timing is determined off the cam apparently. The computer refers to the cold/hot tables via a factor table. By putting the hot and cold tables the same this stops. There are still variations due to ECT and AIT etc etc. I am telling you what has made my crewman run stacks better and on a trip I get 9.1 -9.3 litres/ 100k where I used to struggle to get 13l/100lm.It goes up hills now as well. email [email protected] if you wish. Cheers

[driftnpow]

Yeah theres few things behind the rapid warmup retaded cam timing at startup only assists, with VVT its there to do away with EGR systems of old, getting the engine up to optimum temps quick as possible to reduce emissions, improve fuel consumption when engine is cool, and help reduce engine wear by getting the engine up to temp soon as it can.
Now i didnt say your methods dont work, as older engine designs are a fixed cam im saying in my opinion its not recommended to do it.
I can happily say at sea level the impacts of these changes may not be apparent but ive done a fair bit of alpine climate tuning bein an avid skiier, end of the day engines been sitting in minus temps for 6-8 hours, longer if ya staying weekends sofourth. You dont want that heat to be imediatly wasted out the exhaust on startup.

As for the factoring tables they rule the transition between hot/cold/knock tables.. each have factors basing RPM.. they are individual on ECT, knock severity and calculated drivetrain loadings.

Fuel consumption readings i can quite happily boast after 70000kms of tune trial and error
7.9-8.2 out in the country (hwy and alpine) round suburbs 10-11lt/100 and im very spirited in the way i drive.
That all aside lets not turn it into a fist fight theres plenty of work we all can do to these engines and results are very apparent
Back to how to tuning fuel...

[BigDaddyCool]

ok cool. Now I have a question.... I dont use the hot tables in the cold, I think engine components need time to warm.

Anyway... Given the scanner pid issue with detecting spark from what table. I've run my cold spark table (exhaust min, intake min) in all my tables while I tune for my fuel type.

However....... I still have a knocking issue thats really starting to annoy me. Between like 900rpm to around 2600rpm 'under' 15-25% throttle it's knocking upto 7.4degree's.

I've been lowering the spark n so on, running 60 km's with a few stops and then logging my run back.... then reviewing, lowing the spark etc.

I've dropped like 6 degree's of spark in say 2000rpm and I still am seeing the same level of knocking?

My fuel trims arnt great atm, but it's because it's going from knocking low spark to solid no knocking spark.

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To recap, I have the alloytech manifold insultator, pacemaker headers with 150cell high flow cats followed by two small resonators 1inch from the cats (one each side), middle and rear muffer.
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I figure the insulator and hi-flow setup is the reason why I have to drop the spark so much?

I've considered trying to drop/raise 'airload torque demand' to see the effects or just drop 'optimal torque' to perhaps improve fueling?

I dont really wish to touch maf until the spark is smoothed out.
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Your thoughts guys?

[driftnpow]

Ah look end of the day go on what you feel is right, this is trial and error situation, the engine will quickly tell ya what its happy with and what its not in responce and how it runs overall as i stated earlier the thing with the hot/cold tables is to assist with engine warmup and emittions and how the engine runs at different temp vs loads.

Alrighty what fuel are you running?
There are many factors that induce knock, keep in mind you cant get it all.
As for problem areas, incorrect timing is one, too far Advanced and too far Retarded can too cause this.
Crappy fuel, incorrect afr's (pre combustion)- guesswork here.
Hotspots in the combustion chamber all play into effect, where the areas start to get grey you have to look at the data and interperet what is going on and the cause.
The data will be there, just gotta piece it together patiently, with the right questions one of us be happy to help.

As for other tables dont get in too ahead of yourself 1 step at a time

[Nev1]

I was blessed with knock as well,just with cat back exhaust and cold air intake.The Crewman is a heavy beast which probably does not help either.Biggest thing in reducing the knock was getting the Air Fuel closer and establishing how to adjust the ign timing. Under 2000rpm was hard to sort, but now very close. Retarding spark too far also makes more heat inside the engine which means knock will start easier. 9.1l/100 is pretty good for a Crewman by all accounts,and I got the better figures by adding fuel,then the knock retard went away and the car ran better. Not even close to looking at a fist fight BTW I am too skinny. Car only takes about another 750metres to warm up with the cam timing the same in hot and cold.I can live with that.Ign timing was much more consistent. BTW BDC you say you are changing spark at 15-25% TP. The spark tables are in % LOAD not TP. I got caught with that too. Cheers.

[BigDaddyCool]

load not tps.......... crap, i've spent a week trying to sort this crap out and i've been changing the wrong thing lol ......

arg no wonder i cant smooth it out.

But yeh in my trials, i've definately found u need to smooth it out via maf, injectors and spark..... and sometimes the airload table.

geez...... tps, man that sucks lol ... i'll have to go bring my spark back up in the other area's now. explains alot.

cheers nev. I spent a few days running thru cams, airload and fuel to workout where to get power..... and despite smoothing the car out, power is definately torque and airload ....

u get some serious powerz with those two tables it's just a hard thing, trial and error to smooth out the ride with reguards to diff movement, traction etc.

very touchy. I will say cheers for all ur help guys, every ounce of experience helps heaps aey.