Re: Thread for those of us who tune our own cars
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Re: Thread for those of us who tune our own cars
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BTW, I have 2 almost new Bosch O2s just collecting dust, cannot return them since i lengthen the wires. lol. |
Re: Thread for those of us who tune our own cars
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Before I leave, can I ask one question? If the base fuel table isn't referred to under open loop conditions, then just how does the ECM calculate how much fuel (pulsewidth) to add for any given airflow on your MTF curve? |
Re: Thread for those of us who tune our own cars
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Re: Thread for those of us who tune our own cars
Thanks for jumping in this thread Jeff. Appreciate your insight. Did you notice any misinformation or mistakes with the info I've posted? I want to make sure I'm tuning correctly and not taking any shortcuts.
I'll order a set of motocraft o2 sensors and stay away from Bosch going forward. Thanks! |
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If someone is knows something that I don't I'm always willing to learn |
Re: Thread for those of us who tune our own cars
In closed loop I think it looks at the field were you can adjust the desired stoich. I think my stock value was 14.67 and I changed to ~14.1 for e10. Its the value you have to change for running different fuel besides pure gasoline, i forget the exact name. Then it uses that as a reference to determine closed loop fueling and then as a reference for the commanded lamba for open loop. So in theory, if this value is 100% accurate for my base 91 e10 tune and then I adjust it to the true stoich for my e85 tune, then the only thing I need to change for my e85 tuning would be the timing tables? I'm sure it won't be entirely perfect and I will need to fine tune, but this is just in theory.
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Re: Thread for those of us who tune our own cars
When forced open loop it is always going to be looking at the base fuel table for the commanded lambda once the stabilized operating conditions have been attained (e.g. cold start modifications have expired). This is the commanded lambda that the computer is targeting. For your EEC-V car, the computer won't know where its at hence the need to properly calibrate it. Its going to take the airflow reported from the MAF (simplistically) and then use the commanded lambda from the base fuel table to calculate the desired fuel mass and further calculate the pulsewidth required to arrive at that desired fuel mass. It will not adjust itself. Again, this is where the calibration comes in. Now when you start talking about the Copperhead platform (2011+) the on-board widebands are always feeding back so that the ECM is constantly correcting the fueling. These always operate in closed loop, there is no open loop even under WOT conditions (again ignoring the cold start regime).
Again the point here is to make sure that your base fuel table reflects the commanded lambda that you want to achieve. Then make your MAF corrections so that your actual measured matches this commanded as closely as possible. In theory, if you've done your scaling correctly then your load calculations will be correct and things will be a lot happier all around. |
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Re: Thread for those of us who tune our own cars
Desired fuel mass is an internal calculation based on a number of parameters. Just from memory (so don't kill the messenger if I don't have it 100% correct), but in its most simplistic form:
AFR = airmass/fuelmass therefore fuelmass (Mfuel) = airmass/AFR Mfuel = airmass/(AFRstoich*Lambda) => See how the base fuel table is used <= Now this is very, very simplified. In the speed density world (and somewhat similar in the Ford inferred airflow modeling): Mfuel = ((Pmap*Nvol*Vcyl)/(Tair*.28))/(AFRstoich*Lambda) Again, see how the base fuel is used. Since fueling is what is being commanded (not airflow), the pulsewidth required to deliver that desired fuel mass is then derived from a pretty serious calculation (or series of calculations) using the injector parameters, factored by temperature, pressure, voltage, and a host of other factors. |
Re: Thread for those of us who tune our own cars
Thanks for clearing that up. You can't do speed density tunes with the SCT software can you?
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Re: Thread for those of us who tune our own cars
Not easily by any means. The Ford model is an inferred model; the airmass, load and VE are indirectly calculated (hence the inferred) from the set of linear coefficients found in the speed density category. This gets to be real fun and very complicated in later platforms as it is quadratic in nature and is used in the series of checks and balances for the drive by wire system.
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Re: Thread for those of us who tune our own cars
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I just picked up a 2015 GT and don't even want to get trying to tune that car. But that hellion twin turbo system does look Intriguing. |
Re: Thread for those of us who tune our own cars
So after reading all of your comments guys I feel like I am the dumbest one in this group lol. So doen anyone wanna take a look at my tune before I blow my **** up next time I start the car?
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Re: Thread for those of us who tune our own cars
To guys participating, absolutely love the conversation, you guys are educating many of us that are not replying, so, thanks! I am buying the book today. :)
Even if I do not tune my car right away, understanding everything my tuner tells me is extremely important to me. |
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Jchambers thank you for your much more articulate way of explaining it to dan03mach! I was trying to get there with him earlier but we seemed to be arguing more than anything. No offense dan03mach.
Jchambers well spoken! |
Re: Thread for those of us who tune our own cars
I'm finishing up an excel sheet that will populate the entire load with failed maf table from a datalog of just air flow, rpm, and pedal position. Doing it manually seems like a very time consuming process. I didn't realize how important that table was. I'll upload and share it once I get it all squared away.
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