KP Blown Fox tuning thread

FastDriver

15 Year Member
Sep 5, 2001
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Seaside, CA
#21
Exactly. Assuming you get the Mat density right, it is going to throw everything else off, right?
 
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5.0Thunder

Active Member
Jan 31, 2018
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#22
Should be able to plop the equations into either a Mathcad file or Excel to make things easier. We save calculation templates like this at work all the time to make it easier on the next guys that need to do similar calculations.
 

a91what

SendMeUrDataLog
Mod Dude
Apr 6, 2011
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Hillsborough county
#23
OK... so after doing some basic calcs from a few points in your tune file I think we can fix it. You are running about 30% too fat in boost [the basic math i do is this]

(AFR we have)/(AFR we want)
10/12=.833333 or about 27%
now lets pull a point from the unchanged curve 194* .... the correction to fuel should be (80.7%) so the air is carrying 20% less oxygen so we can reduce the fuel in step. What does your curve have? lets pull from the same temp mark 194* (110%) Your tune is adding 30% more fuel than is needed at this temp.

The deal is i am not sure how far below the minimum AFR you actually are, so what i am going to do is err on the side of safety . I am going to correct the curve in the tune and add 5% to the fuel map above 110kpa just in case. this will still be very safe...

I am also going to build the MAT timing retard table for you as the safety net.
What we will need are some datalogs to verify fuel trims for you, While you jump into boost keep one eye on the AFR gauge and make sure it does not creep above 12.5 and all will be well.
 

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a91what

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Mod Dude
Apr 6, 2011
6,898
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204
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Hillsborough county
#24
I just want to show you a few things that irk me, I cant believe this guy charged you for this... does this car have an idle valve (iac) on it???
Do your headers glow? your idle timing is so low its crazy ( 12*)
The fuel table is a choppy mess, i took the liberty of fixing it on the tune i sent you above.
Kpblownfox fuel table.PNG
this is not a proper fuel table, this is a mess.
bad mat correction.PNG
your mat air density curve

proper mat density curve.PNG
proper curve.
adjusted table kpblownfox.PNG
this is the way i left your fuel table after about 3 mins of work on it, I will need some driving logs of the car under normal conditions to hammer it the rest of the way out.
 

5.0Thunder

Active Member
Jan 31, 2018
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#25
I especially loved the "hole" in fueling at 6k RPM and 10psi. :/
 
Jun 8, 2016
53
18
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Maryland/Delaware
#26
First off thank you for addressing these issues for me. I’m very surprised at the tune being that off, the guy that tuned it has a very good reputation and works with mega squirt often he’s actually the one who convinced me to go with the megasquirt. It’s going to rain until Tuesday in my area so as soon as the weather clears I’ll throw the tune in and data log some drives again thanks so much for fixing everything
 
Jun 8, 2016
53
18
18
26
Maryland/Delaware
#27
As for the idle it dosent have an aic. I haven’t notice and real problems with the idle. What would you estamate the timing should be?
 

a91what

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Mod Dude
Apr 6, 2011
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Hillsborough county
#29
Stock 5.0 HO motors idle at 20*... some like more, some like less... If i were you i would let the car idle at night with the hood open and check to see if the headers start to glow..

As far as the guy that tuned the car is concerned maybe he missed it?? but somehow i doubt it.. MS get a bad reputation for things like this... Now imagine you pullied the blower down so that you only saw 10psi max and held in it until you hit the rev limiter, that hole in the fuel table where the numbers go from around 115 then drop to 90 or less is a major issue. That one spot alone would leave you with parts scattered across the track.... thats 30% less fuel in that one spot, so at this load and rpm point you would see 16 AFR at 10psi and 5500-6000rpm....
 
Jun 8, 2016
53
18
18
26
Maryland/Delaware
#30
I can’t wait to see how it runs with a different tune In it. The motor is a 331 built from the pan up. I wanted a safe tune in it for a while before I turned the boost up but once I got it back from him it just never pulled as hard as I thought it should. I knew 10.1 was to fat but I didn’t have the confindece to start messing with the fuel table. This is my first attempt at any kinda of digital tuning im just now starting to feel comfortable with the mega squirt software.
 

a91what

SendMeUrDataLog
Mod Dude
Apr 6, 2011
6,898
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#37
Let's see how it does with what you have, they are about the equivalent of a 104 which is what I usually recommend.
 
Jun 8, 2016
53
18
18
26
Maryland/Delaware
#40
@a91what sorry I went MIA on this after you helped me, I had some major life and work changes and haven't even been able to get time to start the car in months. but im back on track now I put new plugs in it tonight so tomorrow im going to throw your tune in and make some data logs.