Returnless Fuel System Tuning to Limit Pressure Drop During Fast Shifts

[Dwiggy]

Hi

First time poster.

I have a bad ass Lincoln LS.. My son and I call it the BALLS. no joke

It supercharged with a six speed manual. Over the past 10 years I've made multiple modifications to the car including converting it to a manual and supercharging. My tune works really well considering how complex the PCM is in these cars. At this point, I have a tuning question for Terminator SCT PRP experts.

This seems appropriate for this forum because tuning my car with SCT PRP is very similar to tuning a 03-04 Cobra.

Don't reply about the PPRV. My car does have one, and that's not what I'm asking about. I have read multiple forum posts about this topic. I'm looking for the actual tune.

I get the dead spot after a WOT shift from first gear to second. I'm sure there is a pressure drop when I let off the throttle due to the injectors shutting and then rapidly kicking off when I nail it in second. But, I don't know how to stabilize this pressure.

I've modified all of my torque settings to limit or negate the impact of torque reduction on anything except traction control.

Does anyone have a sample tune for the Cobra returnless fuel system to lesson the pressure differential after upgrading their fuel system?

I am running 47lb injectors, nothing crazy. This isn't massive HP build yet and my engine is actually a Jaguar 4.2 because it's a Lincoln LS. So, my boost is around 14psi, stock for these engines.

If you have questions about my tune, please feel free to ask. I'll gladly share.

Thanks,
Dennis

 

[01yellercobra]

It's not the torque calculation. You need to deaden the response to the pressure. There used to be an article online that listed it step by step. It basically involved zeroing out the PID control for the fuel pump. And I believe there's a pressure limit in the tune that has to be lowered. It was basically fuel pressure+boost psi. In my case it was 40psi plus 20psi. I think I set the pressure in the tune to 70psi for a little extra margin.

Try searching for that article. If you can't find it shoot me a PM and I'll go through one of my old tunes and see if I can find the steps.

 

[HPLouis]

It's not the torque calculation. You need to deaden the response to the pressure. There used to be an article online that listed it step by step. It basically involved zeroing out the PID control for the fuel pump. And I believe there's a pressure limit in the tune that has to be lowered. It was basically fuel pressure+boost psi. In my case it was 40psi plus 20psi. I think I set the pressure in the tune to 70psi for a little extra margin.

Try searching for that article. If you can't find it shoot me a PM and I'll go through one of my old tunes and see if I can find the steps.

This explains a lot. I had Greg from RET's tune read off my PCM and send to me in a MTF file so I could read it with my PRP and try to understand what he did and to also have a base file to make changes to. My car also has the PPRV and there are a lot of changes he did that wasn't in the books I've read and, with a lot of research, I'm starting to see the reason why he did it was to, like you said, deaden the response to the fuel pressure and get rid of that hesitation or stumble between shifts that's common with the PPRV.

Let me search for that article also. I want to learn more about this.

Thanks

 

[Dwiggy]

It's not the torque calculation. You need to deaden the response to the pressure. There used to be an article online that listed it step by step. It basically involved zeroing out the PID control for the fuel pump. And I believe there's a pressure limit in the tune that has to be lowered. It was basically fuel pressure+boost psi. In my case it was 40psi plus 20psi. I think I set the pressure in the tune to 70psi for a little extra margin.

Try searching for that article. If you can't find it shoot me a PM and I'll go through one of my old tunes and see if I can find the steps.

Thank you for this. I'll see if I can make sense of these changes in my tune in PRP and revert.

Dennis

 

[01yellercobra]

The weird thing is I never had the shift hesitation in my 01 when I had the blower on it. I had to run it N/A for a while and the hesitation was so bad the people at the track thought I sucked at shifting.

 

[2003RedfireVert]

So glad I went return style….there are several returnless tables that I didn’t want to figure out or mess with.

 

[01yellercobra]

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. 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. 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) 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. 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 protected] 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>>>>

Mustang Forums and Ford Performance Forums at ModularFords

Typical Hesitation After Shift.. what can be done?

During wot runs on my 03 cobra, when I shift and continue to floor the pedal, the car falls on it's face. Most do the pprv delete but many say it depends on the tuner. My tuner has great customer service and has been trying to take care of the issue for a little while now. What can be done to...

www.svtperformance.com

 

[Dwiggy]

Here are my OEM returnless PID settings.

Fuel Pump Gain Derivative Term: 0.0000
Fuel Pump Gain Integral Term: 0.2500
Fuel Pump Gain Proportional Term: 0.0750

The SCT help manual states that these should be good ranges.

Fuel Pump Gain Derivative Term: 0.0000
Fuel Pump Gain Integral Term: 0.02 - 0.04
Fuel Pump Gain Proportional Term: 0.15 - 0.20

These recommendations are a typo. In the PRP description it states that a good proportional range is 0.025 - 0.05 and integral is 0.15 - 0.40, which makes more sense.

If I don't have to zero these out, I would rather not. However, I'm up for working suggestions.

Which setting controls the maximum pressure drop across injectors? I can't seem to find that setting. It could be described as something else.


Thanks
Dennis

 

[Dwiggy]

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. 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. 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) 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. 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 protected] 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>>>>

Mustang Forums and Ford Performance Forums at ModularFords

Typical Hesitation After Shift.. what can be done?

During wot runs on my 03 cobra, when I shift and continue to floor the pedal, the car falls on it's face. Most do the pprv delete but many say it depends on the tuner. My tuner has great customer service and has been trying to take care of the issue for a little while now. What can be done to...

www.svtperformance.com

Thanks, I'll try this and work on my integral.

"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."

 

[Dwiggy]

New settings.

Fuel Pump Gain Derivative Term: 0.0000
Fuel Pump Gain Integral Term: 0.12500
Fuel Pump Gain Proportional Term: 0.0000

This is nearly perfect!

I'm suspecting that if I get down to the .1074 the barely noticeable delay will be eliminated. At this point I'm going to drive it for a little bit and set the LT fuel trims and monitor the pressure to see how it pans out.


Thank you @01yellercobra!

 

[Dwiggy]

I've learned a few more things today.

When I took a test run and monitored the fuel pressure, with Prop set to 0, the pressure would spike into the high 50's range (55, 56, 57). It never did this with the OEM settings.

So, I changed the settings to the below.

Fuel Pump Gain Derivative Term: 0.0000
Fuel Pump Gain Integral Term: 0.2500
Fuel Pump Gain Proportional Term: 0.0250

This meant that that Integral was OEM but the Prop was divided by three.

During a test run, this resulted in pressures like OEM but more variance in the pressures, less stability.

The loss in power when shifting was not as bad as OEM and about the same as turning the Prop off.

Now I have it set to this.

Fuel Pump Gain Derivative Term: 0.0000
Fuel Pump Gain Integral Term: 0.4000
Fuel Pump Gain Proportional Term: 0.0750

The prop is OEM with an attempt to stabilize the pressure. The Integral is .400 which is the maximum suggestion in the PRP description. With a .4 versus a .25, the integrals are larger. I'm presuming this will return to the correct pressure, more quickly.

At these settings, the loss in power feels about the same as well. It's not as bad as OEM but still there.

Can someone share the stock terminator returnless fuel PID settings?

Thanks,
Dennis

 

[HPLouis]

Sent from my iPhone using the svtperformance.com mobile app

 

[Dwiggy]

View attachment 1769952


Sent from my iPhone using the svtperformance.com mobile app

Thanks!
This is close to where I'm at now.

 

[01yellercobra]

Don't forget to set the pressure limit to match what you're seeing.