How to build a start/stop switch?

[flcruising]

Forgot about that one. Probably by momentarily intercepting the MAIN RELAY (powers the engine devices) through a SPDT relay. Or by intercepting the FUEL PUMP RELAY, though then it may take slightly longer crank duration to restart the engine.

Download the FSM here - http://www.mediafire.com/?wgev1ww9dc1c27g

rodslinger, you forget that with a mtx the fuel isn't cut otherwise it would stall when you press the clutch to cruise to a stop.

 

[cdnballer]

Every time you shut off your engine, you lose power steering. In an emergency situation where sudden lane change is required, you will be at a disadvantage, regardless of how "one with the car" you are. If you care this much about hypermiling, it's better to just coast in neutral or design a flat underbody tray rather than shut off your engine completely.

It's not a matter of experience, driver alertness, or any other factors. It's the simple fact that without power steering, the vehicle becomes significantly harder to handle (if the steering wheel doesn't lock up completely when you attempt to turn it with engine off) and in an emergency situation you lose every time.

Do it on a back-country road, no problem, you only risk yourself. Do it in the city with other drivers/pedestrians/etc is just plain selfish, as you endanger the lives of others.

 

[BRIAN_MP5T]

how would you kill the motor though? If i kill the motor by interrupting the injectors, then I can't rely on PWM that drives it. Hmmm, cam or crank sensor could work, would have to check if the ecu is going to care if i tap off of the signals though. Are you sure that cam or crank is PWM?

I'm sure that the ECU would love to have you momentarily cut the signal to the injectors, without cutting spark resulting in a lean condition, misfire Bank 1 and 2 further resulting in detonation, Check Engine Light, Throwing a code then going into LIMP MODE.

Limp Mode is well known for being economical on fuel.

 

[rodslinger]

rodslinger, you forget that with a mtx the fuel isn't cut otherwise it would stall when you press the clutch to cruise to a stop.

My 08 with a manual trans cut fuel also during full off throttle decel. I can't recall the exact parameters but it was at about 1800rpms when fuel supply would resume to make sure the engine is back under power. About the time you would disengage the clutch for a stop.

And to add that the fuel cut isn't instant upon deceleration. Seems the ECU holds off on the cut for a second or two just to make sure you aren't coming off the throttle momentarily or in the case of a manual trans, coming off the gas just for a gear change. And it takes only the slightest touch of the gas pedal for the fuel supply to return. I've noticed that as soon as the ECU sees any progression on the accelerator pedal position signals it kicks the injectors back to life.

 

[viktor_k]

Every time you shut off your engine, you lose power steering. In an emergency situation where sudden lane change is required, you will be at a disadvantage, regardless of how "one with the car" you are. If you care this much about hypermiling, it's better to just coast in neutral or design a flat underbody tray rather than shut off your engine completely.

It's not a matter of experience, driver alertness, or any other factors. It's the simple fact that without power steering, the vehicle becomes significantly harder to handle (if the steering wheel doesn't lock up completely when you attempt to turn it with engine off) and in an emergency situation you lose every time.

Do it on a back-country road, no problem, you only risk yourself. Do it in the city with other drivers/pedestrians/etc is just plain selfish, as you endanger the lives of others.

You make a good point about PS, but it really isn't as bad as you may think, I was actually surprised that with the size of tires that are on this thing that it is actually easier to turn than the versa with PS off. But nothing like an old ford or other big clunker. I do not think it would put me at a disadvantage, contrary, I think it may save your behind from flipping a car in a situation like that. And no, it doesn't lock up.

 

[viktor_k]

Yes yes, limp mode is very good. But it is a good point about cutting injectors and not cutting spark, that's why I ask and test before I do.

 

[viktor_k]

My 08 with a manual trans cut fuel also during full off throttle decel. I can't recall the exact parameters but it was at about 1800rpms when fuel supply would resume to make sure the engine is back under power. About the time you would disengage the clutch for a stop.

And to add that the fuel cut isn't instant upon deceleration. Seems the ECU holds off on the cut for a second or two just to make sure you aren't coming off the throttle momentarily or in the case of a manual trans, coming off the gas just for a gear change. And it takes only the slightest touch of the gas pedal for the fuel supply to return. I've noticed that as soon as the ECU sees any progression on the accelerator pedal position signals it kicks the injectors back to life.

I do decelarate with engine turning when I'm going down a steep hill or I know that I will have to stop soon anyway, but when you want an extended glide having the engine turn slows you down quiet a bit and robs that momentum, in essence you're wasting energy.

Also, lets not talk about the safety issue with breaks and PS, i'm not a child here and well aware of them. I do appreciate the concern, but i'm not some ultra-green tree hugger that gets out of the car and pushes it to get that extra .01 mpg improvement. This is mostly for fun and experiment and if I don't see that it is safe to do in an area or time, I don't do it. My normal commute is pretty small, and the route is very repetitive, no i'm not going to ride a bike (not most of the time) so its fun trying to keep the tank going for as long as possible.

 

[BRIAN_MP5T]

Yes yes, limp mode is very good. But it is a good point about cutting injectors and not cutting spark, that's why I ask and test before I do.

No matter what you cut to kill the motor, the ECU is going to go LOOPY and trigger a CODE. The ECU is programmed to monitor the situation based on a set of orders. None of the orders are "If the Injectors stop working, Don't worry about it"

Kill Injectors = Lean Condition resulting in detonation.
Kill Spark = Rich condition resulting in poor economy, plugged converters and fouled plugs.

Both will result in poor operation and potential damage, not to mention that on the Mazda 5, the power steering system stops working once the key is returned until the key is cycled at a complete stop.


You are planning to do something that the car isn't intended to do and possibly even damaging it for the sake of Fuel Economy... Further, there is no reason for any of this to improve the fuel economy.

I think that you are actually trolling the forums posting up stupid ideas to get this sort of reaction. Normal people don't come up with such garbage.

 

[viktor_k]

No matter what you cut to kill the motor, the ECU is going to go LOOPY and trigger a CODE. The ECU is programmed to monitor the situation based on a set of orders. None of the orders are "If the Injectors stop working, Don't worry about it"

Kill Injectors = Lean Condition resulting in detonation.
Kill Spark = Rich condition resulting in poor economy, plugged converters and fouled plugs.

Both will result in poor operation and potential damage, not to mention that on the Mazda 5, the power steering system stops working once the key is returned until the key is cycled at a complete stop.


You are planning to do something that the car isn't intended to do and possibly even damaging it for the sake of Fuel Economy... Further, there is no reason for any of this to improve the fuel economy.

I think that you are actually trolling the forums posting up stupid ideas to get this sort of reaction. Normal people don't come up with such garbage.

Brian, I don't understand if I said something or stepped into something, but you seem to be having an "issue" with what I asked. If the forum is for people that don't do anything to cars that they were not designed for, then what are you doing here? Don't know you, but I hope the T in your username is not just the wannabe Type R kind of thing, and as far as I know, protege motor was not "designed" to be boosted.

With that said, I'm not trolling, if no one wants to answer, then be it so, I'll move on.

There is a way to safely kill the car, be it with the SPDT relay or even with temporarily cutting the ignition on the car, just not with a key.

 

[BRIAN_MP5T]

I guess my problem is that I boosted my car, and am one of a select few who "Wrote the Book" when it comes to forced induction with the protege platform.

I had a specific goal with a tangible outcome. My risk was complete destruction of my engine in the search for a 300-400% increase in horsepower.

I see what you are asking and what your goal is, but I do not see any legitimate "Pay Out"

Any effort you make to create a system that will shut the engine down to coast, on paper will save fuel and increase MPG. There is also the problem, compared to what you are focusing on, you can do so much more to save MPG, such as NOT DRIVING 85MPH in an economy Van. You hold 60 MPH, you will see a 5 MPG improvement.

Its obviously not about money, and it seems to be more like a "Can I Do it"

I am saying, why bother and at the same time, If you are successful, who cares.

I put it to you that no matter what you do to coast and glide that Mazda 5, I can beat your economy in MP5T, simply because of the weight of the vehicle, the gearing and my ability to maintain a constant and normal speed.

It's a good idea, just a dumb way to accomplish it with big risks.

 

[viktor_k]

I guess my problem is that I boosted my car, and am one of a select few who "Wrote the Book" when it comes to forced induction with the protege platform.

I had a specific goal with a tangible outcome. My risk was complete destruction of my engine in the search for a 300-400% increase in horsepower.

I see what you are asking and what your goal is, but I do not see any legitimate "Pay Out"

Any effort you make to create a system that will shut the engine down to coast, on paper will save fuel and increase MPG. There is also the problem, compared to what you are focusing on, you can do so much more to save MPG, such as NOT DRIVING 85MPH in an economy Van. You hold 60 MPH, you will see a 5 MPG improvement.

Its obviously not about money, and it seems to be more like a "Can I Do it"

I am saying, why bother and at the same time, If you are successful, who cares.

I put it to you that no matter what you do to coast and glide that Mazda 5, I can beat your economy in MP5T, simply because of the weight of the vehicle, the gearing and my ability to maintain a constant and normal speed.

It's a good idea, just a dumb way to accomplish it with big risks.

Trust me, you'd be going 85mph if a semi truck was about to run you over, you ever drive through nebraska and wyoming? they didn't seem to have a lower limit for the truckers. Put that aside though, I don't drive 85 around here.

Like i said before, the payout is actually there (kind of), for example in the versa I added at least 10mpg, that's around 12$ per fillup or around 100$ per year with my driving. Its not much, but being able to squeeze an extra 120 miles per tank is pretty nice. Soon (about a month) I will know what is the maximum mpg increase I can have in the mazda, if i'm not able to squeeze 10mpg extra out of it, I'll stop doing it.

The problem I'm running into is that mazda doesn't seem to run very smooth when cold, i don't gun it when its cold, probably 5% throttle during accelaration, could be spark plugs, coils, other things... So this whole plan could be void if I have to warm up the car for more than 20 seconds every time.

I'm not going to question your mpg with your protege, i'm going to guess you don't have a stock ecu, so you're just a few keystrokes away from having an "economy" tune.

 

[BRIAN_MP5T]

I can dial in anything I want to the Haltech ECU to get any desired performance.

I really want to keep this civilized so I will say that I do not think you are wrong to ask questions.

I don't understand why anyone would go through that effort to save a maximum of $100, plus possibly break the car, plus possibly continue to piss of his wife by switching off the car when it's moving.

 

[viktor_k]

yea, it may not be worth it but want to try it so it doesn't bother me again. I do have some turbo questions for you, so hope i won't burn a bridge with you.

 

[BRIAN_MP5T]

Not possible to burn bridges with me, glad to help anyone anytime.

 

[Silentnoise713]

I think what some are missing is that our vehicles already use ZERO gas while gliding. With your foot completely off the accelerator pedal when slowing down the fuel supply is cut. I don't mean reduced, fully cut. The fuel supply only returns when you either touch the gas pedal again or you slow enough that the engine does need to produce power to maintain idle or rev slightly for a downshift at speeds below about 30mph.

This is true BUT the fuel supply only cuts out IF you are coasting in gear, which creates drivetrain drag and reduces your momentum so it is not feasible. You can put it in top gear but there’s still a negligible degree of lost energy. If you put the car in neutral (or clutch down), engine kicks in to idle as you coast (vs. glide). The other part of P&G is to shut of the car and glide in neutral, essentially saving idling gas. Having a manual is an important part to bump start without the starter if you really want to push it.

Pulse and glide have been around and in practice for a VERY long time, way before hybrids. It may not be up your ally in terms of fun or rewards but it is an interesting driving technique and does work on any combustion engine. Not sure why everyone is suddenly up in arms, unless this is new to you. Even if one doesn’t practice this, it is good to know and know where you can gain improvement.
http://www.cleanmpg.com/forums/showthread.php?t=1207


Drafting -that is just asinine on any public roads, unless you are on long stretches of hwy and tuckers know/allow you to do it.

 

[cdnballer]

With the amount of effort, time and money it's taking you to figure this out, it's easier to get a part time job at McDonald's. Even if you only make $5 an hour, you'd only need to work 20 hours a year to make up the $100. If you're into saving money, do the math

You could literally make up all your savings in 5 x 4 hr shifts @ McD's.

 

[Gravity]

I think one of the things that has people 'up in arms' is that regardless of how long P&G has been around, or even how much it may save, that there are most definitely conditions that make it unsafe and/or ineffective. Your car itself may be one of those conditions.

From a hypermiling website:

For vehicles that do not feature hybrid drives, pulse and glide is a technique that can only be effectively applied in some conditions. Specifically, you can really only pulse and glide at speeds where your engine will be in DFCO mode when youre gliding, otherwise the benefits of pulsing and gliding will be lost. The best and most obvious application in a non-hybrid car would be at freeway speeds and on a clear, flat road. Pulsing and gliding in traffic and/or at city speeds may be unsafe and will not usually be effective.

Of course we on these forums do all kinds of crap to our cars that they were never designed to do, but generally speaking those things involve relatively high expense, high degree of mechanical knowledge, and in some cases rebuilding or replacing entire chunks of the car to get the desired result. That result is sometimes small, but it is measurable and for guys who say Auto-x for example, those small differences are what the game is about.

It sounds as if with what you were originally asking you were probably hoping for a reasonably simple solution to make the relatively small savings worthwhile. But the answers I'm seeing here seem to indicate that the configuration of your car and ECU may mean that you see minimal to no benefit, and could have some real safety risks.

The most telling comment is that your PS may not come back until the key is cycled after the engine is cut, so you would either have to cycle the key anyway (hence negating the original motivation for this project) or drive without power steering for your whole trip.

I think you'll find that people often get a little 'up in arms' so to speak at anyone in any modification project who attempts to "try it out anyway" after they've been given a few good answers as to why it might not work or be unsafe. The initial evidence here (and I did a little looking myself) seems to indicate that on YOUR PARTICULAR VEHICLE, P&G might not work at all as a technique at best, and could put you in a very dangerous situation in an emergency at worst.

 

[flcruising]

I'm not sure how many ways that viktor_k can reiterate the fact that this is his driving technique already.

I digress.
In the past when I've owned mtx vehicles, have on a number of occasions done the following: upon the approach of a traffic light, depress the clutch (leave the transmission in gear), turn off the engine, set the key back to RUN, and restart the engine by simply releasing the clutch again as long as you're still rolling. Just like popping the clutch for a vehicle with a bad starter, though not nearly as violent.

What viktor_k describes, he wants to do the same thing but with a microcontroller for when he come to a complete stop and ready to restart again. Am I misunderstanding here?? Why you guys think this is something almost immoral is quite funny. Power steering is basically irrelevant when the vehicle is moving above 5-10mph, sure there will be more resistance, but it's EXPECTED!

That being said, the best approach to this may be to just intercept the ignition circuits at the column with SDPT relays and be done with it. This is how you install remote starter systems (though you just tap into the power wires in that scenario), but cutting them for this purpose would be just as basic. Then the PCM wouldn't know - or care - whether you turned the key off or not.

 

[Rockin03mp5]

I appreciate that this thread has become more civil again.

I'm just assuming here, but I think that most of us with mazda5's are generally being safe on the road. This is a family vehicle and people who have families tend to take less risks.

There is always the potential for risk, but I'm sure victor is doing P&G only when safe just like I'm sure that Brian is not going 180 mph everywhere just because he can. At least, I have not seen or heard otherwise.

So, I would like to see this thread stay on topic. If anyone knows about installing a start/stop switch on these cars, post info. If not, leave it alone. When people turbo their cars they don't get questions on if they are going to go 100mph in a school zone.

If you want to keep a civil discussion on hypermiling going, please start another thread.

 

[viktor_k]

Thanks for advice and criticism. PS is not an issue, if it was I'd just hack the circuit so I can run it with ignition off, it is EPS in this year if I'm not mistaken. Also you can get the PS to come back after killing the motor without having to crank the key, but it only happens after enough force is applied on the wheel, like when you're making a sharp 90 degree turn. Either way, it is a non issue. There are other things that concern me more, for example how the motor feels when push-restarted frequently, since in the 30-60 seconds the oil will have a chance to dry up in some areas, still curious in this area. Another issue is the fact that at this moment the car doesn't seem to run smooth when its cold. And last is the fact that the clutch acts different when the motor is shut down. Everything else is hackable, and is just a fun experiment.

Money wise, you're right, it makes little sense, but why do people go to great extents buying a car that is 5mpg better? Surely it doesn't pay off either. But there's something about being a little frugal that makes them feel better. Also, techniques like this can save your behind some day, when you're running late and don't want to stop at a gas station, wouldn't it be nice to know how you can squeeze another couple of miles out of the car?

I've ran across a small kit that does exactly what I'm looking for, but it takes in oil pump sensor, does anyone know if we even have a sensor off of oil pump on these motors?