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Author Topic: What does "dialing in" fuel mean?  (Read 13066 times)
dokalanyi
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« on: February 01, 2016, 02:09:04 AM »

This is probably the noobest of questions, but here goes:
So on the main tuning - S4Wiki, the first thing to do is start with the fueling, until you're "happy with it", I'm just not sure when I should be happy with the fueling. Any pointers? Do I need to get a certain enrichment at certain RPMs?
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adam-
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« Reply #1 on: February 01, 2016, 02:27:04 AM »

It's basically the same for most internal combustion engines running on petrol.  Aim for 12.4 AFR at peak torque, getting richer until the redline.  Aim for 11.8/11.6 at the red line.

It all depends on knock, boost and timing though.  I found the other day with barely any timing or boost I still had loads of knock at 12.4 AFR.  Brought it down to 12.2 and all gone.  Brought timing and boost back in, still no knock.  Got it at 11.6 AFR at the line and it seems good.

I'd get a book to read about tuning.  With these ECU's, you can tune with LAMFA or BTS or both.  I've used both, a little LAMFA to enrich with the pedal and then BTS takes over at 400* (so it's basically always active).  I prefer the resolution available with BTS to use that instead. 

As a footnote, always, always, always do fuelling first.  Ignore timing and boost until you have a fuelling curve you're happy with.  Look at others examples, it's a pretty standard table number wise.  Nothing special, just start at 12.4 and get richer. 
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nyet
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« Reply #2 on: February 01, 2016, 11:40:38 AM »

Also:
It means making sure the trims are near zero at all times for both narrowband and wideband in closed loop.

For narrowband, it also means getting the actual lambda to match requested lambda in open loop.

Excellent question, btw.
« Last Edit: February 01, 2016, 11:42:31 AM by nyet » Logged

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dokalanyi
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« Reply #3 on: February 01, 2016, 11:03:42 PM »

Thanks guys.

So what I understand is, modify LAMFA (read the whole community 1.8 tune, apparently LAMFA is good for beginners), until the curve for AFR (lamsbg_w while logging) is at 12.4 at peak torque (is this load? or is load boost? RPM? Is there a variable to log torque? Anyway, I’m pretty sure I can read up on this, so no worries),

And around 11.6 at the redline (redline starts at about 6500 on my car I think, but the tunes usually increase max rpm to 7k, so I'm assuming from 6500 to 7000).

And make sure there is no knock (I think this means knock voltage is 0, rkrn_w_0, rkrn_w_1, rkrn_w_2, rkrn_w_3)

Once that happens, you have fuelling "dialled in"?
« Last Edit: February 01, 2016, 11:08:12 PM by dokalanyi » Logged
nyet
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« Reply #4 on: February 01, 2016, 11:18:52 PM »

Once that happens, you have fuelling "dialled in"?

If you have non-stock fueling (MAF, injectors, FPR etc.), no. See my post.
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dokalanyi
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« Reply #5 on: February 01, 2016, 11:56:35 PM »

Okay, thank you.
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e_pacman
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« Reply #6 on: March 30, 2016, 07:45:59 AM »

As a footnote, always, always, always do fuelling first.  Ignore timing and boost until you have a fuelling curve you're happy with.  Look at others examples, it's a pretty standard table number wise.  Nothing special, just start at 12.4 and get richer. 

Let's say I did the opposite of what you're proposing, and started with raising the boost a little bit...  Roll Eyes If I'm seeing exactly the same knock voltages and slight timing retard at the same RPM's as I did with the stock file, does that mean I'm still good?
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e_pacman
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« Reply #7 on: March 30, 2016, 08:06:47 AM »

Let's say I did the opposite of what you're proposing, and started with raising the boost a little bit...  Roll Eyes If I'm seeing exactly the same knock voltages and slight timing retard at the same RPM's as I did with the stock file, does that mean I'm still good?

EDIT: That is with a completely stock car btw.
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nyet
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« Reply #8 on: March 30, 2016, 10:50:14 AM »

Let's say I did the opposite of what you're proposing, and started with raising the boost a little bit...  Roll Eyes If I'm seeing exactly the same knock voltages and slight timing retard at the same RPM's as I did with the stock file, does that mean I'm still good?

Generally, with good gas, yes.

On crappy gas (e.g. US 91oct), i'd wait for a really hot day and see if the car still performs the same.
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e_pacman
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« Reply #9 on: March 30, 2016, 12:01:59 PM »

Generally, with good gas, yes.

On crappy gas (e.g. US 91oct), i'd wait for a really hot day and see if the car still performs the same.

Sounds good, thanks!
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ddillenger
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« Reply #10 on: March 30, 2016, 12:04:56 PM »

You can also put your shoes on before your pants. Doesn't mean it's a great idea. You might even ruin something.
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nyet
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« Reply #11 on: March 30, 2016, 12:06:03 PM »

You can also put your shoes on before your pants. Doesn't mean it's a great idea. You might even ruin something.

Now who's being snarky! Tongue

IMO a "bit" of boost shouldn't really break anything, if he left KR alone...
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Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience.
e_pacman
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« Reply #12 on: March 30, 2016, 11:59:07 PM »

You can also put your shoes on before your pants. Doesn't mean it's a great idea. You might even ruin something.

Allright, I have been warned.  Smiley I'll look into the fuelling before I do anything else.
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c4andmore
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« Reply #13 on: January 15, 2017, 09:16:38 PM »

Let's say I did the opposite of what you're proposing, and started with raising the boost a little bit...  Roll Eyes If I'm seeing exactly the same knock voltages and slight timing retard at the same RPM's as I did with the stock file, does that mean I'm still good?

Just some food for thought.. Knock induced timing retardation is a reactive process to try and prevent serious engine damage. The ignition timing retardation only occurs after knock has been initiated. Borderline knock over a period of time often cracks piston ring lands from fatigue. It can also hammer rod bearings and cause warped intake valves from overheating.

In regards to AFR calibration:

Being slightly rich is FAR better than being minutely lean in a boosted engine. ~12.4:1 AFRs at WOT are for NA engines, not forced induction engines. While some folks get away with this lean AFR for some time in a boosted engine, it often requires less timing to prevent detonation and at mid to higher RPM ranges retarded timing reduces power. In addition most O2 sensors can not report accurate AFRs except in steady state mode. In other words under acceleration the AFR reading is typically incorrect as the O2 sensor can not accurately respond fast enough compared to the rate of engine acceleration other than possibly in high gear - if at all. This is also a big issue with chassis dyno testing as well as accelerated engine dyno testing.

IME with WOT engine dyno calibration on a variety of engines a true 11.8:1 AFR in a boosted engine in the lower to mid range is the leanest you want to be for best power without detonation. In the upper RPM ranges most engines want to be in the ~11:2:1 AFR range. Some OE turbo engines use 10.9:1 AFR when in WOT from mid range upwards to allow the excess fuel to cool the chamber/valves to prevent detonation. If you have black smoke out the exhaust pipe of your boosted gasoline engine, the calibration is terribly wrong.

I hope this information is useful. I understand that other people's experience may be different.
« Last Edit: January 15, 2017, 09:19:55 PM by c4andmore » Logged
Lost
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« Reply #14 on: January 15, 2017, 11:21:39 PM »

What kind of fuel are you refering to with those AFRs?

91, 93?
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