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Thread: Tuning the Speed Density section on Ford

  1. #1
    Tuner Blown383's Avatar
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    Tuning the Speed Density section on Ford

    Hello everyone. I am tuning a 2007 Ford Mustang GT/CS with a ton of things done. Namely, a 302 stroker, stock heads, stock intake/TB, mild blower cams, and a single turbo. I still have VCT in place with 20 degree limiters and CMCV deletes. I've got my car running pretty good but cold starts are still very rough and transient fueling is still kind of funky, with lean tip-ins and rich lift-offs. I am thinking this is all related to the speed density section of the tune.

    The car on cold starts experiences extreme hesitation and lean spikes with rapid throttle movement, such as when taking off at a light. It feels like I don't have enough accelerator pump on a carb. After the engine reaches near operating temperature, it runs very good, with some light lean tip-in and rich lift-off.

    I have been reading a lot and I understand the linear relationship of MAP and MAF, or VE and airmass. It seems "MAP at Zero Airmass" is the intercept and "MAP per Airmass" is the slope. I know the formula for calculating cylinder airmass and I have it logging in my scanner but without knowing MAP on these cars, it is extremely difficult to tune these tables. Should I get a MAP sensor and plot Airmass vs MAP and set up a few histograms for each of the RPM breakpoints of the tables, restricting based on cam angle and find the line of best fit or is there a way to calculate MAP based on engine parameters I can log? How does everyone else do it? I know there are some pretty radial stroker/big bore combos out there that are street driven so these tables must be tuneable.

    Any help on this would be greatly appreciated.

  2. #2
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    Have you calibrated the load w/ failed maf tables? Those 2 tables are an essential part of transient fueling and good drivability.

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    Tuner Blown383's Avatar
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    Yes but the issue persists. I ordered a MAP sensor and I'm gonna try tuning the SD stuff to see if it helps. Do you happen to know what the proper PID to use for TPS for tuning the Load with Failed MAF tables is? I'm not sure if I am using the right PID for the table. I've switched between Commanded ETC TPS and a custom PID I made in order to fill in the lowest TPS part of the table.

  4. #4
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    For load I use air load (if you use calculated it'll never be right) and Tps I just use tps angle. Then create a histogram to plot and transfer data. I wish I knew more about the speed density part, I've just never messed with it.

  5. #5
    what injectors are in the car? What is the maf setup (draw through?)



    Ryan

  6. #6
    Tuner Blown383's Avatar
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    The car has 60lbs Siemens-Deka injectors and VMP 75mm housing and a VMP HPX MAF in a blowthrough configuration. The blowoff is mounted on the intercooler so it's not causing any issues.

    I'll try tuning the "Load with Failed MAF" tables with TPS angle to see if it helps. I use "Air Load" for sure. Do you use an average or the max load that you hit in each cell? Do you use a filter? Thanks for the advice.

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    Tuner Blown383's Avatar
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    Alright, here's a new question. Does anyone know what units the "MAP per Airmass tables are in? If I use kPa and g/cyl and write out a calculation by hand, I come up with numbers like 200 vs 21000 in the table. If I use inHg, like the "Map at Zero Airmass" table uses, I come up with something like 50. Does anyone know how to properly write out a function for the speed density section?

    And If anyone is wondering, I am pretty sure tuning these tables will help all of my transient fueling situations and cold start issues. With my increased cylinder volume and cams, the ECU doesn't know its inferred MAP, so it can't adjust fueling properly. I've noticed that the car drives best after an hour or so of driving. At cold start idle, my fuel pressure gauge reads about 31psi. After driving around for a while, the gauge reads anywhere from 45-55psi and throttle response is super snappy and the car drives awesome. I think the car learns all the fuel pump trims and MAF trims it needs. Maybe I'm wrong but this is what I think.

  8. #8
    Is it possible to command it to just have 45psi fuel pressure at idle? Probably just a band aid, but I figure it would be worth a shot? Can you edit the Pump trim tables? If not, then "you're slow". JK man free bump
    Last edited by posenheimer; 08-18-2012 at 07:04 PM. Reason: blowntpi383 should get a sig showing his mods

    Owner/Tuner Street Performance Syndicate

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    Tuner Blown383's Avatar
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    I can't command that much pressure because I'm already near or at my injector minimum pulsewidth. I actually have quite a bit less than the required min PW in the tune to help out DFCO but fuel pump voltage and PW have to be in sync in order to respond to fueling properly. That's returnless for ya. Now looking at the SVT forums, GT500 guys tune these tables I'm talking about to fix their fueling issues. When they get tuned, these tables are what make their little boost gauge change and read more or less boost than stock, since these cars infer MAP rather than have a boost gauge.

    These tables are tuneable so if anyone knows anyone who tunes GT500s, they probably have the information I need. In the mean time, I am going to hook up my MAP sensor and try it out. I have a Super Snake tune and a stock GT500 tune on file and these tables are different between the two. I might take the average between my table and the Super Snake's and calculate a factor to multiply by to interpolate cam timing, since GT500s have no VCT. I'll try that out first to see if it helps at all. Then, once I see some changes, I'll write up some equations to calculate the slope (MAP per Airmass) hopefully, if I can figure out the units. Maybe, it's pounds per cylinder? Any help would be greatly appreciated. Someone send tuning guru Greg Banish my way please. Haha jk.
    2007 Ford Mustang GT/CS: RGR 322 3v - JPC Intake - Vortech YSi-B - Magnum T56 XL - Built 8.8 - Full Suspension
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  10. #10
    eficalibrator is Greg's Screen Name on here. I think that without renting a dyno, the flash in a guess and trial method is the only way, unless that Novi 2200 Stang allows you to peek and you extract data from his tune. But didn't he say that his was all untouched? And it died in front of us that night...

    Nice Sig BTW bro!

    Owner/Tuner Street Performance Syndicate

    06 GTO: D1SC , Full Suspension, 23X .6xx lift Ed Curtis Cam, Mast Heads, Gforce 9" 4.11 Gears, Holley High Rise, Stage 12 Fuel System, Boost By Gear

    01 Duramax: Blown Tranny (again) BWs467 Turbo, Head Studs, Exergy Injectors, Lift Pump, Moonshine
    2014 Taurus SHO: (Wife's Car) OR DPs, Tuned, CAI
    2006 TBSS; AWD SLP Catback, K&N CAI, Tuned

  11. #11
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    The offset is in inHg. Map per airmass is 'unit less' as far as im concerned?

    In other SD ford systems (in simple terms) airmass in lb per intake stroke = (MAP - offset)/slope where offset is inHG and the slope is undefined. Im not familiar with the GT500 but am with the focus and Aussie SD systems.

  12. #12
    Tuner Blown383's Avatar
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    Okay. I understand that. Ford's systems should be very similar across the world. How do you Aussies tune SD in Fords?

    Here's what I've learned...

    I asked around about the speed density tables and I got this hint of US patent #6115664 which turned out to be very helpful. Learning how to tune a Ford 3v from scratch with software that isn't really supported by the industry is VERY difficult to say the least.

    After carefully reviewing the patent, I can see that Ford uses inHg for MAP and lbs/cyl for airmass/aircharge, just like you said. In HPTuners, MAP is the Y-axis and airmass is the X-axis, opposite of the patent. There is a linear relationship between airmass and MAP and it can be found easily in theory...

    I know I can come up with my airflow model by logging MAP in inHg and airmass in lbs/cyl and hit each RPM point and hold. At each RPM point, I would need to get a low load number and a high load number, or low/high MAP. Command the cams for a range between 0 and 20 degrees, depending on how I rescale that table since I have limiters. Take MAP and airmass readings at the exact same RPM point and subtract low load numbers from high load. Bingo! There's the slope or "MAP per Airmass." Input a point from earlier data into y=mx+b along with the slope and solve for b. There's the intercept or "MAP at Zero Airmass." Simple algebra.

    For all the low RPM cells, that wouldn't be too hard to do. For the high RPM, that would be tough, even on a dyno as HPTuners just doesn't have the datalogging resolution. Plus I just don't like the idea of holding RPM very high for extended periods.

    There has to be an easier way to calculate this stuff on Ford's. I know the Aussies have been doing it for a while as I can look at their tunes and it's nearly the same stuff, only with MAF disabled, BUT I believe they have a factory MAP sensor. It's only inferred here in the States. Now, I wonder how much of a role it plays in fueling since the Alpha-N stuff (Load tables) plays a huge role. I know most guys here in the States never touch this stuff but since I have a more radical combo, I think it deserves some look, especially with the lack of general Ford tuning knowledge out in the open.
    2007 Ford Mustang GT/CS: RGR 322 3v - JPC Intake - Vortech YSi-B - Magnum T56 XL - Built 8.8 - Full Suspension
    2008 Ford Shelby GT500: VMP Gen 2 - ATI 15% - SCJ TB - Full Bassani Exhaust - Full Suspension - Upper Pulley - Meth Injection - JLT 127mm

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    Most Aussies don't touch SD, they just fudge the injector scaling and base fuel table to meet the engines fuel requirements. The Aussies SD model does indeed read MAP from a t-MAP sensor. The difficulty with the Aussie SD on the VCT cars is that there is a unique slope and offset for every can angle. This makes tuning the slope and offset table very time consuming and very demanding on the engine as you suggested. I find that the relationship you described above is not linear and other factors come into play. I have a heap of data on the Aussie SD cars which has been derived using SCT livelink as this allows access the the ford specific direct memory requests. Aussie tuners don't share much sonim quite reluctant to go into detail and provide the algorithms that I have derived. In short if you are rich or lean by the same amount at different MAP, then your slope is out. A lower slope value will equate to a higher airmass and therefore lead to a longer injectors pulse width per intake stroke. If you are rich or lean by differing amounts at different MAP then your offset is out. As with the slope a lower offset will ultimately increase the injector pulsewidth.

  14. #14
    You think you got it bad. I'm stuck trying to tune a 2005 BA Falcon with a 2007 GT500 motor dropped in it but using the Falcon PCM. I have no MAF or TPS. Another tuner had it for 4 months and bailed. My boss said I could fix it but I'm struggling. It is running way rich and I'm feeling out of my depth I feel your frustration.

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    Tuner Blown383's Avatar
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    Thanks for the tips, IH8TOADS. I'll keep that in mind. I wonder why all the GM guys share most of their info when the Ford guys like to keep secrets. Haha. Oh well. I might be jumping to SCT sometime soon. I like HPTuners and the fact one interface can cover so many vehicles but it is definitely in need of work on the Ford end. Especially PID/DMR support and faster datalogging. Without DMRs, I don't see a way to properly tune a returnless fuel system.

    MADWHIP, I can understand your frustration. You should be able to copy the "Load with Failed MAF" and all the speed density tables straight out of a stock GT500 tune, along with all the x/y-axis breakpoints and such. I would just copy everything that I possibly could from a stock GT500 tune straight into the Falcon tune, including all the axes. I think that would get you pretty close. You also have to remember the injector slopes are a little funky with GT500s as the injectors are actually quite small for the motor and as such, Ford bumps up the fuel pressure with the returnless system to compensate for a potential small injector situation. Is there no way to modify the Falcon harness to use the GT500 TPS? Isn't it pretty much 0-5v worldwide?
    2007 Ford Mustang GT/CS: RGR 322 3v - JPC Intake - Vortech YSi-B - Magnum T56 XL - Built 8.8 - Full Suspension
    2008 Ford Shelby GT500: VMP Gen 2 - ATI 15% - SCJ TB - Full Bassani Exhaust - Full Suspension - Upper Pulley - Meth Injection - JLT 127mm

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    Where are you located, MADWHIP? With no VCT, it should be fairly straight fwd. HP can't access the load dependent modifiers on the BA so you won't have access to all SD tables.

  17. #17
    Thanks guys, I have copied a stock GT500 tune with the x & y axis and it is still rich like .73 lambda at idle I'm commanding 1.44 on my fuel base but like the honey badger falcon don't care. The owner installed the engine and done the wiring this is no doubt some of the issue. I set the fuel pressure to 48 psi via it's after market regulator. This car has 2 fuel pumps in the standard falcon cradle and I'm wondering if that is half my problem as the two are running together all the time. There is a TPS hooked up but I just can't see it on my scanner.
    IH8TOADS I'm in NZ. I called Mario at VCM to see if it was doable and they were not sure. I guess this will be a job I learn a lot from can't do Holdens and XR6 turbos everyday
    I work alone here with a dyno and have no one to ask when I get stuck on something odd I guess this is learning. Sorry for hijacking the thread.

  18. #18
    You may have this same problem with 60lb injectors I had. Looks they are to big for idle, for me helped this:

    http://www.hptuners.com/forum/showth...idle+injectors

    so min pw to 1.
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  19. #19
    Have You finally found how to tune map per airmass tables? My car is driving good with cams, but I'm sure this tables needs to be adjusted.
    Eastern and Central Europe American Muscle and Harley-Davidson tuning
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  20. #20
    Quote Originally Posted by MADWHIP View Post
    Thanks guys, I have copied a stock GT500 tune with the x & y axis and it is still rich like .73 lambda at idle I'm commanding 1.44 on my fuel base but like the honey badger falcon don't care. The owner installed the engine and done the wiring this is no doubt some of the issue. I set the fuel pressure to 48 psi via it's after market regulator. This car has 2 fuel pumps in the standard falcon cradle and I'm wondering if that is half my problem as the two are running together all the time. There is a TPS hooked up but I just can't see it on my scanner.
    IH8TOADS I'm in NZ. I called Mario at VCM to see if it was doable and they were not sure. I guess this will be a job I learn a lot from can't do Holdens and XR6 turbos everyday
    I work alone here with a dyno and have no one to ask when I get stuck on something odd I guess this is learning. Sorry for hijacking the thread.
    Where in NZ are you located?