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| fuel pump control http://gemellocattivo.com/forum/viewtopic.php?f=19&t=166 |
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| Author: | mk e [ Sat Oct 24, 2015 9:23 am ] |
| Post subject: | fuel pump control |
I add a basic fuel pump control this morning There is an enable to turn the pump on/off and a prime time for the pump to run at key on. I put it on pin c2-55 which is the pin AEM uses for furl pump thinking it's best to match there pinout whenever possible. The probably is I'd like to add a fuel pressure control so people with big fuel pumps like me aren't using a lot of power heating up the fuel....but c2-55 doesn't have a function PWM available. I think I'm going to just write something to do it....(it's just a time 4 or 5 lines or code to force the pin to PWM then another 5-10 lines to PID control the PWM dutycyle) but for the moment the fuel pump works. |
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| Author: | apalrd [ Sat Oct 24, 2015 12:33 pm ] |
| Post subject: | Re: fuel pump control |
For fuel pressure control, we do this: -Fuel pump control runs in the 5ms task -If the fuel pressure sensor is above the set pressure, turn the pump off -If the fuel pressure sensor is below the set pressure, turn the pump on The end result is a 200hz PWM and pretty good pressure regulation. Since the injector model includes delta-P, a bit of error is tolerated. |
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| Author: | mk e [ Sat Oct 24, 2015 2:14 pm ] |
| Post subject: | Re: fuel pump control |
That's very simple and I have a delta-p built in as well. I would have to play with that a bit because while enginelab has 8 threads that have a skip number they aren't exactly tacks on a ms clock so I don't know exactly the next time they get run..... but I could add a 5ms timer to a thread. |
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| Author: | mk e [ Sat Oct 24, 2015 7:35 pm ] |
| Post subject: | Re: fuel pump control |
apalrd wrote: For fuel pressure control, we do this: -Fuel pump control runs in the 5ms task -If the fuel pressure sensor is above the set pressure, turn the pump off -If the fuel pressure sensor is below the set pressure, turn the pump on The end result is a 200hz PWM and pretty good pressure regulation. Since the injector model includes delta-P, a bit of error is tolerated. Do you still use a regulator or do you dead-head the fuel rail? I'm pondering dead-heading my rail thinking that if I go to the bother of writing code to regulate the pressure why go to the bother of plumbing in a regulator? At what rate are you sampling the fuel pressure and any idea what the response time of the sensor your using is? I ask because enginelab does not update injection time once the pulse has begun so I need the pressure relatively stable. I wrote a generic PWM routine while dinner was cooking that seems to work....not sure how I want to use it yet.... |
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| Author: | apalrd [ Sat Oct 24, 2015 9:03 pm ] |
| Post subject: | Re: fuel pump control |
When we did this we dead-headed the fuel rail. We did not vary the pressure setpoint, it was fixed at 4 bar gauge. We now use an in-tank pump with 4 bar (58 psi) regulator and don't do pressure control, since the fixed pressure regulator is lighter than the pressure sensor with fittings. This was not true with an adjustable regulator which was quite heavy. Most OEM systems have a regulator set fairly high and PWM to a lower pressure. The regulator is in-tank with the pump. |
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| Author: | mk e [ Sat Oct 24, 2015 9:39 pm ] |
| Post subject: | Re: fuel pump control |
I'll have to think about this a bit....I added a coolant fan control output and a Tach output while I was thinking. I need to get the ECU to powered up correctly and see everything work off the simulator and in real life. |
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| Author: | cribbj [ Sun Oct 25, 2015 5:20 am ] |
| Post subject: | Re: fuel pump control |
Mark, on other cars I've run a conventional return system, with the rail mounted regulator, set to 3.5 bar, but I PWM'd the pump down to 9 volts or so at idle & cruise, so that I was returning only minimal amounts of heated fuel to the tank. |
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| Author: | mk e [ Sun Oct 25, 2015 7:16 am ] |
| Post subject: | Re: fuel pump control |
cribbj wrote: Mark, on other cars I've run a conventional return system, with the rail mounted regulator, set to 3.5 bar, but I PWM'd the pump down to 9 volts or so at idle & cruise, so that I was returning only minimal amounts of heated fuel to the tank. That was my first plan....and still may be the way I go. It's also easy to make the PWM duty cycle be tied to load & rpm or just required fuel and pick numbers that get you just to the point the regulator is flowing. If I did that I could use a little fixed pressure regulator on the rail rather than the big adjustable regulator I have. Its also easy to add a PID feature....but then it needs to be tuned which is maybe not so easy. Then there is the very simple on/off apalrd described......lots of options. I have all the parts to put a regulator on so that's probably where I'll start |
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| Author: | mk e [ Sun Oct 25, 2015 2:09 pm ] |
| Post subject: | Re: fuel pump control |
I'll just add a 3 way selector.... 1) Timed prime then on when the engine is turning 2) Timed prime then on when the engine is turning with the output PWMed to a table 3) Prime until pressure is reached then PID to pressure when engine is turning I started setting up the PWM table control this morning. |
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| Author: | mk e [ Sun Oct 25, 2015 9:06 pm ] | ||
| Post subject: | Re: fuel pump control | ||
The pwm table is work and tied to Fuel_Req [g] The way engine lab work everything runs all the time so I decided to just have the PWM on all the time and if you don't want it you just set it to 100% in the table. I also decided to skip the PID option at least for now....I'll just install a regulator and give it no more thought.
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