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Old 07-15-2005, 11:25 AM   #1
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Default The Official Help Tune Knight Fire Thread



This is for people who are helping me tune Knight Fire.
Mainly Foghorn, but I'm hoping others (Rogue, etc) might join in.

Off topic posts will be delete w/o warning.

Here are the results from my last 2 scans.....

This is the results & my tables/formulas for calculating IFR.
http://rubix.ca/Bonnie/97SSEi/ifr_test_04work.xls

These are the results from using the IFR table calculated in 04work.xls
http://rubix.ca/Bonnie/97SSEi/ifr_test_05.xls

My LTFT values are between -3.91 & +2.34 with an avg of -1.36

So.... what'* the next step?
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Old 07-19-2005, 11:59 PM   #2
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Hate to tell you...but I'm not a big fan of adjusting the IFR Table at different MAP settings in order to set up the LTFTs.

As far as I'm concerned, the injectors flow a given amount of fuel in a given amount of time at a given pressure. Since the IFR table only has entries in 10 Kpa increments, it'* kind of like tuning with a shotgun.

let'* just look at your IFR table for a second. The stock values are 207.17 Miliseconds/Gram across the entire table if memory serves me correct. The Grand Prixs, despite having almost identical hardware, have an IFR table that has lower values at higher MAP settings. Why lower you ask? Because as MAP pressure increases so does the fuel pressure, that'* why you have a vacuum diaphram on the Fuel Pressure Regulator.

Now, if we look at where you have arrived in your IFR table, you have values that increase with MAP pressure. What you are saying is that it takes the injector longer to inject a gram of fuel as the fuel pressure rises...that is wrong.

I know you have a Walbro fuel pump, which was not likely needed, but there may be a problem with the instalation, which is not unheard of, that is preventing it from delivering sufficient fuel. I'll give this scenario a low possibilty rating but keep it in the back of your mind.

I prefer to calculate the injector flow rates, likely ending up with either a flat table or slightly decreasing values towards 100 Kpa in the IFR. This can then be tweaked globaly by selecting all entries and either adding or subtracting a percentage value. There are exceptions but we'll get to that later.

I prefer to tune the LTFTs using the MAF table. Think about it, you have a table from 1500 Hz to 11500 Hz in what, 175 Hz increments? it'* far more granular for adjusting than the IFR table. Not only that, the graduation from one entry to the next is a much smaller increment that the change in values in your IFR table.

Now, you've been looking at the LTFTs as THE starting place...but there'* more to it than this one dimension. Personnaly, I could give a rat'* if I end up with a less than perfect LTFT if, for example, I now have KR because I've upped the timing. Since you, nor I, have a wideband O2 sensor to tune with, then O2 narrowband values will take a back seat to any KR problems.

If you perfect the LTFTs before you add timing then you might find you'll then need to add fuel to quench KR, means you'll do all this adjusting so that you can then start over as soon as you make another change.

Still, even if you look at the timing and change it, you haven't yet considered where you want the TPS% value for PE (Power Enrichment) Enable. It'* an important consideration because that will determine the range of MAF Hz values just before you go into PE mode. Stock value is 60%, mine is 30%.

You also have things like the AE (Acceleration Enrichment) TPS% enable values and re-enable values to worry about not to mention the actual AE% values themselves and the AE MPH Multiplier Table.

Sooooooo....no I don't like your starting point. Why tune the injectors to your car? Why not tune the MAF table to tell the PCM how much air it'* actually receiving and let it manipulate the IPW (Injector Pulse Width) correctly.

You know this could be an endless discussion...but I type with 2 fingers and am not sure I'm up to writing a novel.

Hope this helps.

Cheers,
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Old 07-20-2005, 08:59 AM   #3
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Quote:
Originally Posted by Foghorn
As far as I'm concerned, the injectors flow a given amount of fuel in a given amount of time at a given pressure. Since the IFR table only has entries in 10 Kpa increments, it'* kind of like tuning with a shotgun.
I was following the tuning guide provided on the DHP website. I couldn't find any good examples of how-to tune via the MAF table.

Quote:
Originally Posted by Foghorn
let'* just look at your IFR table for a second. The stock values are 207.17 Miliseconds/Gram across the entire table if memory serves me correct. The Grand Prixs, despite having almost identical hardware, have an IFR table that has lower values at higher MAP settings. Why lower you ask? Because as MAP pressure increases so does the fuel pressure, that'* why you have a vacuum diaphram on the Fuel Pressure Regulator.

Now, if we look at where you have arrived in your IFR table, you have values that increase with MAP pressure. What you are saying is that it takes the injector longer to inject a gram of fuel as the fuel pressure rises...that is wrong.
What you're saying does make sense, I was reading the table wrong, I thought higher valuves = more fuel.

Quote:
Originally Posted by Foghorn
I know you have a Walbro fuel pump, which was not likely needed, but there may be a problem with the instalation, which is not unheard of, that is preventing it from delivering sufficient fuel. I'll give this scenario a low possibilty rating but keep it in the back of your mind.
I do own the fuel pump.... but it'* not installed yet.... still running on the stock pump. I actually was debating on installing the fuel pump at all.


Quote:
Originally Posted by Foghorn
I prefer to tune the LTFTs using the MAF table. Think about it, you have a table from 1500 Hz to 11500 Hz in what, 175 Hz increments? it'* far more granular for adjusting than the IFR table. Not only that, the graduation from one entry to the next is a much smaller increment that the change in values in your IFR table.
I don't know how to tune using the MAF table.

Quote:
Originally Posted by Foghorn
Now, you've been looking at the LTFTs as THE starting place...but there'* more to it than this one dimension. Personnaly, I could give a rat'* if I end up with a less than perfect LTFT if, for example, I now have KR because I've upped the timing. Since you, nor I, have a wideband O2 sensor to tune with, then O2 narrowband values will take a back seat to any KR problems.
Again.... I was starting w/ the tuning guide on DHP'* website.

Quote:
Originally Posted by Foghorn
If you perfect the LTFTs before you add timing then you might find you'll then need to add fuel to quench KR, means you'll do all this adjusting so that you can then start over as soon as you make another change.

Still, even if you look at the timing and change it, you haven't yet considered where you want the TPS% value for PE (Power Enrichment) Enable. It'* an important consideration because that will determine the range of MAF Hz values just before you go into PE mode. Stock value is 60%, mine is 30%.

You also have things like the AE (Acceleration Enrichment) TPS% enable values and re-enable values to worry about not to mention the actual AE% values themselves and the AE MPH Multiplier Table.

Sooooooo....no I don't like your starting point. Why tune the injectors to your car? Why not tune the MAF table to tell the PCM how much air it'* actually receiving and let it manipulate the IPW (Injector Pulse Width) correctly.
So where is my starting point? Grasshopper is ready to learn.
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