PowerFC: Some DIY tuning comments please

[Dale FZ1]

I've made a few extra changes with now up to +6deg over stock in the N5L5:N8L8 area, and graduated ramping up/down in that area. Will post up the ghost trace to show what areas of the map are accessed in light cruise and light acceleration approaching but not getting into boost.

Result is definitely a more eager response to the throttle and no obvious problems or noises. Max knock value showing is 37, running ambient temps about 28deg, inlet air temps 36, AFM max output 3800mV and injector duty about 42%.

[Dale FZ1]

I've made a few extra changes with now up to +6deg over stock in the N5L5:N8L8 area, and graduated ramping up/down in that area. Will post up the ghost trace to show what areas of the map are accessed in light cruise and light acceleration approaching but not getting into boost.

Result is definitely a more eager response to the throttle and no obvious problems or noises. Max knock value showing is 37, running ambient temps about 28deg, inlet air temps 36, AFM max output 3800mV and injector duty about 42%.

Fuel consumption is predictably good, probably because the injector duty cycle is down (most running is off boost for evaluating this parameter change). Provided there are no obvious running problems I will check it over another full tank this coming week.

[paulr33]

is that with pod in engine bay or airbox with stock snorkel? knock is a little bit high, you should check with your tuner to make sure its ok

[justin911]

hmm i got a question...

now im guessing the timing belt is related to the timing on the pfc...

say my timing belt is old and i should probs get a new one, would advancing the timing put heaps more strain on the timing belt ??

[paulr33]

interesing question, i would love to hear an official answer

i dont think it would cos the cam timing is just altered

one would think the maximum amount of "torque" on the timing belt is near redline in say 4th gear when on full load, i wouldnt imagine a big timing upshift on medium or light load would put more strain on the timing belt vs 6000rpm in 4th gear. that being said you should make sure you get the timing belt done, in some cases do it before 100,000 comes up. i believe if the belt snaps you crown the pistons and kill them completely. ie: new pistons

[Emre]

Guys,

Quickly skimmed over this thread and here is my advice : Do not fark with what you don't know. It's an expensive toy to experiment with if you happen to to get it wrong !!!

It starts with altering a value here and there to see if it made a difference or not and by the end of the week, your tune is all over the place because you can't remember what you had done a few days ago, or what the original value was. If you feel confident, disregard this advice.

Small corrections you make won't be that noticable on the road unless your tune was farked to begin with. Adding 5 degrees on light throttle will not give you an extra 100 kms out of a tank of fuel. Ignition can make the drive crisper but is not that detrimental to the fuel consumption. If your AFRsare in the 11s on light throttle, bumping the ignition to save fuel is not the right way to go about it. While the weather is cool you can get away with extra ignition, but don't forget the summer is around the corner.

From what I've seen, default ignition maps are on the aggressive side to begin with and needs to be trimmed under load. Most noticable knock will occur as the torque peaks, which is (depending on car, turbo size, boost run, etc...) around N08-09,L08-10 for a stockish setup.

AF correction is as the name suggests, Air Flow Correction and has nothing to do with the ignition map. It's for quick adjustment of your AFMs. The default value is 100 on all the voltages and if you changed that value to 110, at that voltage level your ECU will be compensating for %10 more air, thus running richer.

If closed loop is enabled, any adjustment made on the fuel map is reduntant on light throttle, therefore if your O2 sensor/s are buggered this may be the cause of your poor fuel economy.

If your ignition is not set correctly by the CAS (15 deg for GTS-T and 20 deg for GTR) the value shown on your hand controller is not correct to begin with. You maybe passing wrong info to others, in values to try.

Knock sensors are a great tool to have from factory, but their sensitivity can be different from one car to another. What your tuner perceived as safe on your car may be dangerous on another. Well, sensitivity is the wrong word as they all should be calibrated the same, but the noises it picks up can be different in each car.

Advancing the timing alters the duration the inlet valve opens at, the extra strain on the timing belt is not an issue.

Lastly, you should also ask yourself, whether any huge improvement you notice is in fact a placebo effect or not. You make an alteration with expectations of a positive change and at times you feel the car drives much better when in fact it's not much different.

[PlasticStan]

Advancing the timing alters the duration the inlet valve opens at, the extra strain on the timing belt is not an issue.

What are you talking about? Altering the timing in the ECU affects the point when the spark plug ignites, it has nothing to do with the cam timing, valve opening or duration!!!!!

[paulr33]

thanks for clearing up that emre, good to have a 3rd opinion

will take feedback on board thanks

[Emre]

What are you talking about? Altering the timing in the ECU affects the point when the spark plug ignites, it has nothing to do with the cam timing, valve opening or duration!!!!!

<{POST_SNAPBACK}>

You are right.

For some reason when the timing belt was mentioned, i went to cam timing mode. The question wasn't about the cam timing, but i thought it was. The answer still remains the same.

[justin911]

hmm im just trying to understand it all still

so advancing the timing wont have any impact on the timing belt ???

[Dale FZ1]

Appreciate constructive criticism of efforts to improve the spark mapping.

Remember I'm running base fuel maps and no increase in stock boost. Boost level in any event should have no bearing on the light load spark timing and knock. Before making any changes, first thing I did was create a spreadsheet of the base ignition map, and make detailed notes so I can revert to that setting without trouble. It also means I can make incremental and smooth changes to the map.

I agree with the general approach Paulr33 adopted in trying to gain some improvement without putting the integrity of the engine into question through detonation - hence the use of ghost mapping to identify the map area where changes should be made.

My intent has not been to achieve fuel consumption improvement - just cleaner, snappier engine response where it does most running. I know also that the best way to get fuel economy and engine response is to spend the $$ and have the AFR monitored. Just figured that if the fuelling is conservative then I can yield some improvements until the funds are available for a tune. Meanwhile I learn a bit more about the operation of the PFC.

BTW, I've identified the conditions to achieve a 38 knock level and will make a small adjustment. Otherwise it's no more than 15. Check SK's comments about knock level and it appears neither number is likely to be significant. The rider on that comment is that a tuner wearing "knock headphones" is best qualified to comment.

None of the above is about self justification, just explaining the intent and process. Small steps forward means progress.

cheers

[The Mafia]

well, do you guys think it is safe to advance the timing up to 20 degrees in some areas to get better response, even if the knock is at the most, 5% ?

Edited October 28, 2005 by The Mafia

[rob82]

If your advancing the timing over 20 degrees and your motor is still together then something must be wrong ie- your static timing number must be overly retard alot or your compression is like 6:1. This whole comparing knock figures is bullocks. Different motors, different sensors different knock levels.

Do you guys realise that its unlikely under light to medium throttle that you will not hear a knock event without a chassis ear. I've found by a rule of thumb that base PFC timing maps to be very sharp with 2-6 psi of boost on board between 2500 - 3500rpm. I know its temping to fiddle but if you go to a reputable tuning shop you shouldn't have any worries about your tune; hence pay the extra and be happy that its right.

[The Mafia]

hhmm... I am getting more and more confused..

my tuner is telling medifferent things...

He said he adds up to 20degrees into some ls1'scause they are so doughy off the mark, and says the knock is fine..

anymore opinions?

[rob82]

Your tuner doesn't have a clue, 20 degrees into an ls1 - bullshit!!! I chip at least 5-6 LS1's a week with various levels of tune and I can tell you that if he is adding in 20 degrees more at any point on a standard DFNN or DSKW file than it will rattle.

[The Mafia]

ok, well maybe I misinterpreted him. Maybe he meant that he had some spots UP TO 20 degrees, not 20 degree's on top of what wa already there.

He's NEVER EVER blown up a LS1, and I've seen regular edits from him running 240rwkw with over 400nm of torque. (he has a dyno dynamics dyno)

I really need to look at this a little more... I am a little worried now. Can anyone else give some input?

Edited October 29, 2005 by The Mafia

[justin911]

i've got no clue about this as your all aware hehe but on mine if i increased the timing anything over say 10 in the light load areas shed knock like a whore.. like 50 +.

I'd be to scared to change it to 20 on mine..

[paulr33]

good to speak to you Jono, as I said it varies back some timing out and then see if you dont loose what you original gained and then go from there or leave it as is, i dont plan on turning my up too much more

[The Mafia]

I went bac kthrough my timing adjustments, and had a look, and I was a little incorrect, my highest adjustment was 14 degrees.

I counted a few wrong.

I've gone back to a 6 degrees advance accross the forst 10 x 20

[Dale FZ1]

I went bac kthrough my timing adjustments, and had a look, and I was a little incorrect, my highest adjustment was 14 degrees.

I've gone back to a 6 degrees advance accross the forst 10 x 20

<{POST_SNAPBACK}>

Just be a little careful. Remember you've now got something that is configured way differently from a std RB25. With the sort of turbo and intake mods you've got there will probably need to be a way different approach to both fuel and spark.

IMO not good to take too much notice of the amount of variation that may go into an LS1 - dynamics of combustion in a 2 valve 700+ cc/cyl engine will be nothing like a 4 valve 415cc/cyl RB.

I'd err on the side of caution and make the changes smaller as you have. As commented earlier, remember the ambient temps can/will have an impact on knock resistance.