Cruise Control (with MPG sensitive logic)

[mjspiess]

Originally Posted by oldbeaver

Question:

What instrument you have to set the cruise at 60 mpg? I think you can slow down until getting to 60 mpg but this will last for a fraction of a second !

Please, explain.

OldBeaver

The only instrumentation I have is an MPGuino. This is a devise mainly for OBDI vehicles to show live MPG. So when I say "set the cruise at 60 mpg", I get up to 57 mph let off the gas slightly, but still maintaining 57 mph I can push Set on my cruise control when the MPGuino shows that I am currently getting 60 mpg. Once I do this, the cruise locks in at that given engine load because the cruise is hooked to the Ford MAP sensor measuring the engine vacuum. The cruise then maintains 60 mpg. It fluctuates between 57-61 mpg.

It should be noted that I have a highly modified '95 Geo Metro which allows me to lock into such a high MPG at a higher rate of speed. Here is a list of everything I've done to help improve gas mileage: MPGuino, Passenger Mirror Delete, Retracted Radio Antenna, Removed Side Trim, Aero Windshield Wipers, Clear Plastic Headlight Covers, Disabled DRL, Full/Partial Grill Block (depending on time of year), Rear Tire Spats, Front/Rear Belly Pan, Rear Wheel Skirts, Front Wheel Arch Gap Fillers, Sealed Headlight Gaps, Partial Kammback, XFi Camshaft with 60A +2* Sproket, Advanced Ignition Timing 8* BTDC, Hot Air Intake Tricker, Coolant Temperature Sensor Tricker, Full Synthetic 5W30 Oil, Aluminum Underdrive Pulley, XFi 3.79 Transmission, Pennzoil Synchromesh Transmission Fluid, Solar 12v Assist, 50 PSI Tire Pressure 155/80R/13, '99 Hyundai Accent 12 lbs. Rims & MPG Sensative Cruise Control

[mjspiess]

I unhooked the cruise VSS wire to the MAP sensor hoping the cruise would just use the RPM to set the speed, but it would not work. With this new finding, it would be very difficult to change from MAP to VSS on the fly. My only KISS option would be to run the VSS and MAP to a relay on a switch so I could easily switch the wire hook up, but then I'd have to change the PPM on the cruise before I left for my trip, which wouldn't be hard since the "brain" is in my car. The real easy option would be to find a MAP sensor that would be campatable with 4000 PPM so I could just switch between MAP & VSS and not mess with the cruise at all.


Here is a video I took today:

http://www.youtube.com/watch?v=oLIOX...ature=youtu.be

[mjspiess]

Does anyone know if any other car manufacturers used digital MAP sensors? From my research, digital MAP sensors use a square wave output in frequency whereas analog MAP sensors us a voltage output. Ford is the only make I can verify. I'd like to find a MAP sensor using higher frequency so I could keep my cruise set at 4000 PPM and just put the VSS & MAP wire on a relay/switch.

[mjspiess]

I installed an SPDT switch today to enable switching back and forth from the MAP sensor & VSS. I also switched the PPM to 8000 on the cruise servo to give it another try now that I know how the cruise reacts when hitting the Set button. Initially the cruise would over react, then under react, and repeat. I now know, when setting the cruise to a certain MPG, you need to keep your foot over the gas pedel so it doesn't over/under react. Once it settles, it's good to go. So I gave it a try at 8000 PPM and it works just fine.

Out of curiosity, I switched from MAP to VSS on the fly and to my surprise, it works just fine! All I have to do is reset the speed/MPG and it's good to go. I assume it's working because 8000 PPM is perfectly divisible by 4000 PPM and the servo is seeing every other pulse? Either way, I am really happy I can set my cruise at a given speed or MPG at the flip of a switch

[oldbeaver]

Originally Posted by mjspiess

The only instrumentation I have is an MPGuino. This is a devise mainly for OBDI vehicles to show live MPG. So when I say "set the cruise at 60 mpg", I get up to 57 mph let off the gas slightly, but still maintaining 57 mph I can push Set on my cruise control when the MPGuino shows that I am currently getting 60 mpg. Once I do this, the cruise locks in at that given engine load because the cruise is hooked to the Ford MAP sensor measuring the engine vacuum. The cruise then maintains 60 mpg. It fluctuates between 57-61 mpg.

It should be noted that I have a highly modified '95 Geo Metro which allows me to lock into such a high MPG at a higher rate of speed. Here is a list of everything I've done to help improve gas mileage: MPGuino, Passenger Mirror Delete, Retracted Radio Antenna, Removed Side Trim, Aero Windshield Wipers, Clear Plastic Headlight Covers, Disabled DRL, Full/Partial Grill Block (depending on time of year), Rear Tire Spats, Front/Rear Belly Pan, Rear Wheel Skirts, Front Wheel Arch Gap Fillers, Sealed Headlight Gaps, Partial Kammback, XFi Camshaft with 60A +2* Sproket, Advanced Ignition Timing 8* BTDC, Hot Air Intake Tricker, Coolant Temperature Sensor Tricker, Full Synthetic 5W30 Oil, Aluminum Underdrive Pulley, XFi 3.79 Transmission, Pennzoil Synchromesh Transmission Fluid, Solar 12v Assist, 50 PSI Tire Pressure 155/80R/13, '99 Hyundai Accent 12 lbs. Rims & MPG Sensative Cruise Control

I think you are making a clever use of the cruise control. However, you don´t mention if you are looking mean mpg or instant mpg of MPguino.

If you are using mean yield, I can tell you that always the mpg yield will converge to a mean value. After a long run, it will be difficult to alter that value.

Use instant mpg instead, and you will see that it variates A LOT depending on almost any factor, even if you keep the throttle fix, or if you set cruise control. And I mean A LOT.

However, if you look the MEAN mpg over a long run, it may seem to you that you can control mpg yield with the throttle, but this is an ilusion.

Anyway, what you are doing with the cruise is smart: seek a desired mpg, once you get it, set a cruise speed, and keep it. It should yield the same mpg if the road conditions do not variate and IF you show MEAN mpg on the display.

Best,

OldBeaver

[mjspiess]

That is the next experiment. Does this actually improve gas mileage over a full tank of gas? Now that I can easily switch back and forth from MAP to VSS, I'll run a few tanks with MAP only & a few tanks with VSS only and see what happens. Like you've pointed out, during usual cruise, my MPG would get as low as 34 mpg on the longest steepest hill and well into the 100s on the down side of the hills with stretches in the 40s, mainly in the 50s, some in the 60s and on rare occasions some in the 70s. It seems to me, it prob. all averages out. The MAP sensor mod might edge it out over the long haul. We shall see

As far as a "safety" preference, it'd prob. be best to use the MAP on side/back roads where you don't experience much traffic behind you and VSS on highway when some people can approach your rear pretty quickly. Once I get a good feel for when the MAP vs VSS is most beneficial, I'll prob. do just that. VSS on highway & MAP on side/back roads since most side/back roads tend to be more hilly and on my particular commute, it was more difficult to make my MPG continue to climb from exiting the highway.

[oldbeaver]

Originally Posted by mjspiess

That is the next experiment. Does this actually improve gas mileage over a full tank of gas? Now that I can easily switch back and forth from MAP to VSS, I'll run a few tanks with MAP only & a few tanks with VSS only and see what happens. Like you've pointed out, during usual cruise, my MPG would get as low as 34 mpg on the longest steepest hill and well into the 100s on the down side of the hills with stretches in the 40s, mainly in the 50s, some in the 60s and on rare occasions some in the 70s. It seems to me, it prob. all averages out. The MAP sensor mod might edge it out over the long haul. We shall see

As far as a "safety" preference, it'd prob. be best to use the MAP on side/back roads where you don't experience much traffic behind you and VSS on highway when some people can approach your rear pretty quickly. Once I get a good feel for when the MAP vs VSS is most beneficial, I'll prob. do just that. VSS on highway & MAP on side/back roads since most side/back roads tend to be more hilly and on my particular commute, it was more difficult to make my MPG continue to climb from exiting the highway.

Sorry MjSpiess, I am slow today. Can you explain a little more what is VSS and what is MAP in yr experiment?

I saw you take both signals from somewhere and now are able to use one or the other to do something. I think to set cruise control ON.

However, I am not clear if you are using the "keep speed constant" as control logic, or if you have programmed a different logic for cruise control, such as the one Jomel Maldonado developed and showed in this Forum.

Please, clarify these three things, so that I can follow and participate.

Tks, OldBeaver

[mjspiess]

VSS = Vehicle Speed Sensor
MAP = Ford MAP sensor with vacuum line hooked to intake manifold

Both VSS & signal wire from MAP are connected to SPDT switch & VSS wire for cruise is installed on the common feed for the switch, so the cruise servo is getting feedback from either the VSS (speed) or MAP (load/MPG).

I haven't programmed anything. I basically did exactly what Jomel Maldonado did initially clear back on page 3. He went a step further by buiding an ardiuno with code to tell the cruise to automatically switch back and forth from VSS or MAP based on upper & lower set speed limits. His setup is "smarter" than mine in that it does this automatically. My setup is all manual. All I have is a Ford MAP sensor, 5 volt regulator, SPDT switch & MPGuino to see live MPG.

[mjspiess]

Instant MPG is upper left and mean/current trip MPG is lower left in the videos.

I drove 467.1 miles on 8.247 gallons of gas for an average of 56.4 MPG. Top speed was 70 mph & average moving speed was 48 mph. This is up 1.52 mpg from last tank and up 2.9 mpg from my last regular cruise tank. Looking back through my fuel log, all my tanks with an average moving speed of 48 mph & regular cruise control, averaged 51.87 mpg. Keep in mind, I've done some other aeromods to my car, but I am now up 4.58 mpg in this tank.

[oldbeaver]

Originally Posted by mjspiess

VSS = Vehicle Speed Sensor
MAP = Ford MAP sensor with vacuum line hooked to intake manifold

Both VSS & signal wire from MAP are connected to SPDT switch & VSS wire for cruise is installed on the common feed for the switch, so the cruise servo is getting feedback from either the VSS (speed) or MAP (load/MPG).

I haven't programmed anything. I basically did exactly what Jomel Maldonado did initially clear back on page 3. He went a step further by buiding an ardiuno with code to tell the cruise to automatically switch back and forth from VSS or MAP based on upper & lower set speed limits. His setup is "smarter" than mine in that it does this automatically. My setup is all manual. All I have is a Ford MAP sensor, 5 volt regulator, SPDT switch & MPGuino to see live MPG.

Ok, Mj, let me think of it all:

On any cruise control we have three main elements:
1) A reference or monitor variable, we want to keep constant. We get the value from the engine with a sensor.
2) A control variable, which is the fuel injected per time unit.
3) An effector to execute the control, based on our logic. The solenoid of the cruise control over the throttle on old cars, or using a electronic mechanism in newer cars.

In a standard cruise control system (speed logic), our order is “keep speed constant”, so the monitor variable we use is the speed signal of the car (VSS).
The control variable is the amount of fuel supplied to the engine.
The effector is the solenoid that actuates on the throttle, or an electronic mechanism.

On a mpg logic, our order would be: "keep mpg constant" (or within some narrow range). Let us examine the three elements in this case:

The reference or monitor variable would be different, mpg, value we can get from our onboard computer, MPGuino or such.
The control variable is exactly the same, amount of fuel supplied per unit of time. This is important as allows us to use the same Cruise control system we have, the same hardware.
Yes, because the effector device would be the same, we don´t need to change it.

In yr MAP sensitive logic, the MAP signal is used, hoping this will produce a good mpg result. Your order is: “keep MAP constant”, and the system would supply less or more fuel as to keep it constant.

It makes sense to me.

I drive a diesel car, which hasn´t MAP but has a MAF sensor and signal, which may play the same role as MAP as to be the control signal. My computer gives me mpg in real time, so I can see how good is that MAF signal (or other I may choose) to keep mpg constant at certain level.

See sensors sense here:
Mass Airflow MAF Sensors

Do you think MAF would work on a diesel engine?

OldBeaver