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Interesting fueling issue with my tune.

7K views 81 replies 24 participants last post by  Dilemma 
#1 · (Edited)
Hmm.

You would think a knock fuel enrichment map would ADD fuel, right?

Not the case. :rolleyes:

Stock:


Knock:


Yay, less fuel. Oh, and the timing is the same too. Neato.:mad:

Big ups to JZW for telling me about this, and helping me figure out how to fix it.

Assuming you will never go off the fuel stock map is dumb, and that's what has happened here. Not too thrilled.
 
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#4 ·
Thats weird, though from what I have read you NEVER want to enter the Knock Fuel Map.

But you're right, it should add more fuel to cool the cylinders down. I think it even says that exact thing in the T5Suite pdf.
 
#10 · (Edited)
Thats really odd man. There has got to be some reason why Frank tuned the knock map that way. Have you looked at other fuel maps to see if they are heavily rich to do what the knock map would basically?

Jeeze the x-range is shorter by .48 on the negative end while the positive end isn't that far off, only .06.
 
#22 ·
In my opinion they are tuned that way so that even if a little knock is detected, it does not slow the car down...

If the car is well mapped, which this one is done fairly concervitive, 98% of the time it will never go into the knock maps and that is all good and well until you get bad gas, have a di go south, plug faul or whatever. If it does go into the #2 knock maps, there is no timing retard and less fuel... That would cause boost to be pulled out a some point... Hopefully soon enough eh!

The idea is to have a little safety margin. I have my car now mapped so that if it does sense knock in high boost and in the load or above it will add more fuel and pull out 2 degrees of timing. That way I will feel the car slow down and actually know that I have encountered knock and might want to let off the throttle;)

Also, boost is mapped in what some call the "duct tape" method in that it is mapped with reg con mat instead of the much more precise pid controls.

The pid controls take more time to figure out and get to work right, but when they do, they work much better!!!

Like I have said before... Custom tune..... Glad I did not pay custom tune prices for that....

John
 
#13 ·
That's a stock tune?! Wow!

...kidding.

If you look though, only a few values are Knock Map < Main Fuel Map, most of them the knock is greater than the main fuel map.

If you have t5 check for anomolies it should give you a nice report of all the ones that are less.
 
#18 ·
I'm going to load it into t5 suite, and add 2's to where its not correct, and then eventually re-flash the ecu. (along with some other stuff I have changed)


I have the Sqr tune saved in 4 places I can go back to that of need be.
 
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#25 ·
That is not the way I understand it. The way I understand it, if knock is protected, it goes to the #2 ignition map and knock fuel map.

FYI, I have 15 tunes now, pro and stock and this is not just related to this pro tuner. There are many more that do similar things....;) Some don't, but I also wonder since no one could look at these before and how much of an effect this had on tuning. I will map it this way, no one will ever know kind of thing... Now that has all changed....

John
 
#19 ·
Is there a boost request and timing map for knock or does it just pull values off the fuel maps and compinsate for it? if theres seprit mabs then this map doesnt seem too off... what the stock one look like?
 
#24 · (Edited)
Nevermind, looking at this same map table at the momment.

X=MAP value
y=RPM value
z=fuel mass/injector flow?

I'm so confused now trying to figure out how we go from the decimal values in the table to whatever the value on the z-axis is.

OK so I've figured out a little bit about the table. Obviously our first column on the left is RPM and that translates to the 3D graph on the y-axis perfectly.

As for our top row it took me a bit but I found it out. The top row is gauge pressure from the MAP sensor. However the x-axis is absolute pressure from the MAP sensor. The x-axis is in kilopascals and the first table row is in BAR. So if we take -.36 bar * 100 Kpa we get -36 Kpa (1 BAR=100 Kpa). So we see we have a vacuum of -.36 Kpa gauge pressure. Now add 100 Kpa to -36 Kpa to get absolute and voila. We end up at 64 Kpa absolute which is our first value on the 3D graph for the x-axis.

WHY OH WHY COULDN'T THEY LEAVE THE TABLE AND GRAPH BOTH IN ABSOLUTE OR GAUGE. I only figured out the BAR to Kpa because 1.4 bar is a familiar value to me being 20.3 psi and it all clicked after that.

I'm still at a loss for the value z-axis for the injector flow though.
 
#26 ·
JZW, read my above post, I looked at the map in T5suite myself (a stock map I have on my computer) and figured out the values and the axis about 98%, just not certain of the z-axis value calculation from the table to the graph.
 
#36 ·
There are more than one way to skin a cat and with all the maps that tie together, there is more than one way to adjust fueling for sure.

I personally like to have the "fail safe" ignition knock maps and the fueling knock maps. That way if you get into trouble by advancing the timing too much or getting the system too lean, it will sense the knock and swithc over to the "fail safe" maps and richen the mixture and pull some timing out... This is exactly what you want!

The stock bin files have it pull a bunch of timing. I see numbers in the 3-7 degree range;) It also depends on what you are doing with the car!

Drag racing is a 12-13 second run and you can get away with things that you could not if you were road racing or doing long wot pulls like Vigge likes to do. You have to consider the power and application and hw and that will determine what you can get away with in terms of fuel and timing and how safe you want the knock maps to be.

If you only do a third gear pull every now and then, you could get away with much more than if you like to wind second through 5th out and get on it a few to many times a day...

John
 
#31 ·
Well, you'd have to look at a lot more maps, its true. The T7 files are very complex compared to T5.

But once the algorithms are set up and everything is documented pretty well it should not be that much more complex to look at the really important maps.

And flashing the ECUs is not much more complex at all. I have one successful T7 flash under my belt, it was nice and simple, and the car actually runs! :shock: :D
 
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