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The Terminator
Engine/Tuning
Returnless Fuel System Tuning to Limit Pressure Drop During Fast Shifts
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<blockquote data-quote="01yellercobra" data-source="post: 16844955" data-attributes="member: 35549"><p>I knew I had posted it before. I take no credit for this. I just found it. I think I put the important parts in bold. The rest is good info. </p><p></p><p>Pretty scary, huh? The military figured out the electronics were reacting too quickly to the pilot inputs. Pilots were used to slow acting hydraulics and cable controls. The control systems were working too good!! The solution….. deaden inputs to the electronic control system. Once the electronics were slowed down enough to act like mechanical controls the system worked fine. That’s oversimplification of the whole problem but that’s it in laymen terms. Now, the way I see it is the pcm is overreacting to an unusual event in the fuel system. It’s been explained many times here so I won’t get long winded. Essentially there is a huge spike induced because the injectors are suddenly shut down because the driver jumps off the pedal. The fuel system is doing it’s job. Supplying huge volumes of fuel and high psi. The pcm shuts down the pumps because of way way too much pressure seen by the frpt.(albeit very high and for a very short time) Meanwhile driver grabs next gear and slams the pedal down making the injectors/engine want a lot of fuel. Uh oh the processor shut the pumps down. Now the fuel system has to regroup and start supplying enormous amounts of fuel. Fuel pumps have to spool up and the pressure needs to build again. All this takes time. The root of the problem is the pcm overreacting to the initial pressure spike. In a way the same as the fly by wire on the F8-C. So how do you deaden this input? We use a combination of things. Some have already been tried but not all of these together that I know of. In reality we are putting a muzzle on the fuel control system so it does not over react to the initial spike.<strong> First ( and probably most importantly) we clip the pressure sensor transfer function. (this is the pid we had to have Diablosport add). When you think about it if a car makes 17 lbs boost and you want 39 psi delta you never really need more than 56 psi absolute rail pressure. So in that case we would clip the pressure transfer function at about 60 psi. If you make more boost make the clip a little higher. ( say 22 lbs boost…. 22 boost + 39 delta = 61 absolute rail pressure….. I’d clip it at about 63 or 64 to give it a little room) The program has it clipped at 78, that’s 15 psi too much even for 22 lbs boost. This way even when this huge spike happens the pcm never sees it.</strong> That’s the biggest part of the battle. That’s why removal of the pprv helps. The pcm sees the spike and reacts but the extra fuel is stuck in the line for that split second and by the time the pcm does it’s thing the pumps are back on and everything is cool again. (This really is a very very small window that is causing this to happen.) That’s why, depending on driving style, some experience it worse than others. It depends on the speed of your go pedal foot. I’m not a fan of pprv removal. (flame away I’m speaking from MY experience) The pprv really helps if you don’t allow the fuel control to overreact. The initial spike is there but not as long. Plus cold start is better (no big deal really) <strong>The second way we muzzle the fuel control is with the PID control. I put the proportional at zero. (yes I said zero) then we cut down the integral to some where around .1074 . Leave the derivative at zero. We have datalogged this and the fuel system is stable.</strong> We have big fuel supplies in these vehicles to make that kind of power. You don’t need to micromanage (remember the F8-C). Make sure your MAP sensor max counts are set to 1023, adjust your load with failed maf table up (this is one of the things the pcm looks at during sudden transitional changes) I have attached an excel file to give a good starting point for most higher boost cars. The main thing is your loads are going to be higher so make them closer to reality. ( they really don’t have to be perfect) and lastly ( in my opinion the least critical since it’s adaptive) tweak your fuel pump voltage table. On some cars I don’t even mess with it. That’s it in a nutshell. Clip the pressure transfer function, lightened the PID control, get your load with failed maf close to reality, max out the map ad counts, and fiddle with the voltage table. What I feel we are doing is basically putting a muzzle on the fuel system so it doesn’t over react. This has worked on many of our customers Cobras. We have not had any problems with it. If you need any help with this shoot me a pm or email me …. <a href="mailto:jerry@suttonhp.com">jerry@suttonhp.com</a> We can custom tune your car or even send a mailorder tune with the fixes in it. Hope this helps and sorry to cause such a stir. (some of you take things way too serious, you should get a hobby J/K)</p><p>Have a great weekend.</p><p>Attached FilesTerminator failed maf table.xls (13.5 KB, 54 views)</p><p>Heres oringal thread link>>>></p><p></p><p><a href="http://www.modularfords.com/forums/s...578#post998578" target="_blank">Mustang Forums and Ford Performance Forums at ModularFords</a></p><p></p><p>[URL unfurl="true"]https://www.svtperformance.com/threads/typical-hesitation-after-shift-what-can-be-done.826610/[/URL]</p></blockquote><p></p>
[QUOTE="01yellercobra, post: 16844955, member: 35549"] I knew I had posted it before. I take no credit for this. I just found it. I think I put the important parts in bold. The rest is good info. Pretty scary, huh? The military figured out the electronics were reacting too quickly to the pilot inputs. Pilots were used to slow acting hydraulics and cable controls. The control systems were working too good!! The solution….. deaden inputs to the electronic control system. Once the electronics were slowed down enough to act like mechanical controls the system worked fine. That’s oversimplification of the whole problem but that’s it in laymen terms. Now, the way I see it is the pcm is overreacting to an unusual event in the fuel system. It’s been explained many times here so I won’t get long winded. Essentially there is a huge spike induced because the injectors are suddenly shut down because the driver jumps off the pedal. The fuel system is doing it’s job. Supplying huge volumes of fuel and high psi. The pcm shuts down the pumps because of way way too much pressure seen by the frpt.(albeit very high and for a very short time) Meanwhile driver grabs next gear and slams the pedal down making the injectors/engine want a lot of fuel. Uh oh the processor shut the pumps down. Now the fuel system has to regroup and start supplying enormous amounts of fuel. Fuel pumps have to spool up and the pressure needs to build again. All this takes time. The root of the problem is the pcm overreacting to the initial pressure spike. In a way the same as the fly by wire on the F8-C. So how do you deaden this input? We use a combination of things. Some have already been tried but not all of these together that I know of. In reality we are putting a muzzle on the fuel control system so it does not over react to the initial spike.[B] First ( and probably most importantly) we clip the pressure sensor transfer function. (this is the pid we had to have Diablosport add). When you think about it if a car makes 17 lbs boost and you want 39 psi delta you never really need more than 56 psi absolute rail pressure. So in that case we would clip the pressure transfer function at about 60 psi. If you make more boost make the clip a little higher. ( say 22 lbs boost…. 22 boost + 39 delta = 61 absolute rail pressure….. I’d clip it at about 63 or 64 to give it a little room) The program has it clipped at 78, that’s 15 psi too much even for 22 lbs boost. This way even when this huge spike happens the pcm never sees it.[/B] That’s the biggest part of the battle. That’s why removal of the pprv helps. The pcm sees the spike and reacts but the extra fuel is stuck in the line for that split second and by the time the pcm does it’s thing the pumps are back on and everything is cool again. (This really is a very very small window that is causing this to happen.) That’s why, depending on driving style, some experience it worse than others. It depends on the speed of your go pedal foot. I’m not a fan of pprv removal. (flame away I’m speaking from MY experience) The pprv really helps if you don’t allow the fuel control to overreact. The initial spike is there but not as long. Plus cold start is better (no big deal really) [B]The second way we muzzle the fuel control is with the PID control. I put the proportional at zero. (yes I said zero) then we cut down the integral to some where around .1074 . Leave the derivative at zero. We have datalogged this and the fuel system is stable.[/B] We have big fuel supplies in these vehicles to make that kind of power. You don’t need to micromanage (remember the F8-C). Make sure your MAP sensor max counts are set to 1023, adjust your load with failed maf table up (this is one of the things the pcm looks at during sudden transitional changes) I have attached an excel file to give a good starting point for most higher boost cars. The main thing is your loads are going to be higher so make them closer to reality. ( they really don’t have to be perfect) and lastly ( in my opinion the least critical since it’s adaptive) tweak your fuel pump voltage table. On some cars I don’t even mess with it. That’s it in a nutshell. Clip the pressure transfer function, lightened the PID control, get your load with failed maf close to reality, max out the map ad counts, and fiddle with the voltage table. What I feel we are doing is basically putting a muzzle on the fuel system so it doesn’t over react. This has worked on many of our customers Cobras. We have not had any problems with it. If you need any help with this shoot me a pm or email me …. [EMAIL]jerry@suttonhp.com[/EMAIL] We can custom tune your car or even send a mailorder tune with the fixes in it. Hope this helps and sorry to cause such a stir. (some of you take things way too serious, you should get a hobby J/K) Have a great weekend. Attached FilesTerminator failed maf table.xls (13.5 KB, 54 views) Heres oringal thread link>>>> [URL='http://www.modularfords.com/forums/s...578#post998578']Mustang Forums and Ford Performance Forums at ModularFords[/URL] [URL unfurl="true"]https://www.svtperformance.com/threads/typical-hesitation-after-shift-what-can-be-done.826610/[/URL] [/QUOTE]
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Returnless Fuel System Tuning to Limit Pressure Drop During Fast Shifts
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