Fuel Pressure Regulator

[Ryland3210]

I read the word proportional to indicate infinite values, constantly variable, no just the 2 values that you measured.

Given your measurements I think they were incorrect when they said, "The regulator varies the fuel pressure proportional to the vacuum applied"

Sorry again, for not reading your reply to Ryland.

 

Dave, your interpretation of "proportional" is the normal one. Dan M's testing experience says otherwise.

 

I'll make a change to the FAQ on that basis, although I'd sure like to take one of these beasts apart. What surprises me about Dan's data is two things:

 

1. I am familiar with hydraulic pressure control valves of many kinds, having designed systems based on them for many years. I'm aware of valves which vary the pressure proportionally with a reference pressure, but not one as Dan M describes.

2. Varying output pressure proportionally with reference pressure makes sense for this application.

 

However, perhaps a proportional type regulator was tried and was found to experience early failures, as Dan M has suggested, and a new type of valve with only two modes was created in an attempt to make them last longer.

[Ryland3210]

Constant throttle, constant rpm, going up hill = High load, the engine is overcoming the mechanical losses in addition to gravity, etc.

 

Same throttle, constant rpm, going down same hill = Low load, the engine is being driven by the rear wheel which will help over come the mechinical losses, etc.

 

Yes going up the hill we would end up opening the throttle to maintain a constant rpm and going downhill we would close the throttle to maintain a constant rpm.

 

We often forget that our engine to run at constant RPM the crankshaft really us undergoing vast changes in accel and decel. During just after TDC compression our expanding fuel mix is exerting a great amount of pressure down on our piston, our crankshaft is in a state of acceleration. After approx 3/4 of the power stroke our crankshaft now is transitioning to decel. It continues to undergo a reduction of rpm with the greatest amount of decel during the next compression stroke.

 

Yes our second piston will affect this, but lets keep it simple.

 

Up hill our mechincal efficiency is decreased, downhill our mechanical efficiency is increased. The volumetric efficiency of an engine is a function of its mechanical efficiency. Volumetic efficiency is a measurement of how well an engine fills a cylinder to its capacity.

 

 

Yes it can. Our bike are an example of this. But it will never be better that its orginal estimate of the predicted airflow through an engine. Do our engines run differently with tight or lose valves, why cant a alpha-n system compensate for that?? It has no way to measure airflow. It merely knows what should be going through. Which may or may not be the case. Valve setting affect our valve timing and airflow right?? A MAP sensor would relay that info to be used for fueling calculations.

 

I understand it the other way around. Mechanical efficiency is a function of volumetric efficiency.

 

Actually, brake specific fuel consumption (mechanical efficiency) generally improves going uphill, unless one is going at WOT and redlining it. This is because the efficiency of spark ignition engines improves from idle through somewhere in the region of the middle of its RPM range and around 1/3-1/2 of its rated horsepower. For example, when going downhill at mid RPM, as compared to uphill, the engine friction is still there, but power output is low, and in addition, energy lost is increased along with intake manifold vacuum. It's also why my vehicles all get better MPG at 55 than they do at 30. All of this paragraph is in terms of the efficiency of power production of the engine, which is the conventional measure of mechanical efficiency. To make it clear, it is not about how much fuel it requires to to up versus down hill at a specific speed.

[Ryland3210]

You said it. The model cannot compensate for the variables. Air density changes power output for a specific throttle opening. Hence changes load. The system that does not sense vacuum or air flow cannot compensate, that is why is is not accurate!

Here's a test for you. Run an engine at a set throttle opening on a hot, dry day with a vacuum gauge hooked up. Mist cold atomized water in front of the air intake. Watch vacuum gauge. The change is small but the vacuum rises as does RPM because the power output of the engine also rises. What happens when power goes up? Load goes down. Same throttle opening. A fixed fuel model cannot know this or compensate.

 

Funny how these two different sites refer to each of these as load sensors. Don't you think?

http://www.kemparts.com/TechTalk/tt06.asp

http://autorepair.about.com/cs/generalinfo/l/bldef_495.htm

 

Bottom line is I think we all know how this stuff is measured and works. I think we are at odds on the terms we are using.

Hint: Never say dampen around here.

 

Water injection lowers the temperature of the intake air, thereby increasing its density, and providing a supercharging effect. Heavily loaded piston engine driven bombers during WWII used water injection to increase takeoff power. Claims were as high as 30% increase! Forty years ago, I used it on my '67 Barracuda by connecting my windshield washer hose to the carburettor intake.

 

I agree with your example, so no need to experiment to convince me. It's simple physics, with real world proof. However, I'm confused by your saying the load goes down as RPM goes up. That makes no sense to me. Power output increases due to the increased mass flow rate of the air/fuel mixture (assuming that fuel flow is increased as the water is injected to keep up with the increased air mass flow rate), but that is independent of the load.

 

By the way, doesn't the ECU include an absolute pressure sensor in addition to engine and air temperature? If so, our beloved fuel injection control system isn't all that dumb, and probably the only significant improvement in accuracy would derive from a mass flow sensor, rather than a MAP sensor.

[emry]

Here is some casual reading.

 

http://www.bosch.com.au/content/language1/html/4557.htm

 

or http://apps.bosch.com.au/motorsport/downloads/regulators.pdf

 

and

 

http://apps.bosch.com.au/motorsport/downlo...chtip0505_1.pdf

 

and

 

http://www.auto-ware.com/combust_bytes/eng_sci.htm

 

or

 

http://en.wikipedia.org/wiki/MAP_sensor

 

Maybe some is related to this ever growing thread. Cheers.

[Dan M]

Thanks for the links Emry.

 

This one especially: http://apps.bosch.com.au/motorsport/downlo...chtip0505_1.pdf

 

Seems to agree with what I have been failing to get across.

 

 

Ryland,

 

I did not say load goes down when RPM goes up. I said load goes down when power output goes up.

Load is calculated as a percentage. An engine making more horsepower under the same conditions experiences less percentage of load. This is how the ECU looks at the data.

 

The ECU's absolute pressure sensor is not connect to the engine's vacuum. Hence it is merely a baro sensor to compensate for barometric pressure. Not a "manifold absolute pressure" sensor. I don't know if it adjusts on the fly but usually in less sophisticated systems they sample baro then the key is cycled on and sets the value for that run. This approach can hamper operation if one were to start the engine at sea level and climb elevation. Later systems adjust on the fly, I just don't know if our ECU does.

 

As I've been saying from the beginning, it is all about accuracy. Without knowing load it is simply not very accurate.

I'm glad at least Emry agrees.

[Ryland3210]

Thanks for the links Emry.

 

This one especially: http://apps.bosch.com.au/motorsport/downlo...chtip0505_1.pdf

 

Seems to agree with what I have been failing to get across.

 

 

Ryland,

 

I did not say load goes down when RPM goes up. I said load goes down when power output goes up.

Load is calculated as a percentage. An engine making more horsepower under the same conditions experiences less percentage of load. This is how the ECU looks at the data.

 

The ECU's absolute pressure sensor is not connect to the engine's vacuum. Hence it is merely a baro sensor to compensate for barometric pressure. Not a "manifold absolute pressure" sensor. I don't know if it adjusts on the fly but usually in less sophisticated systems they sample baro then the key is cycled on and sets the value for that run. This approach can hamper operation if one were to start the engine at sea level and climb elevation. Later systems adjust on the fly, I just don't know if our ECU does.

 

As I've been saying from the beginning, it is all about accuracy. Without knowing load it is simply not very accurate.

I'm gald at least Emry agrees.

 

Your wording was: "The change is small but the vacuum rises as does RPM because the power output of the engine also rises. What happens when power goes up? Load goes down." So, it clearly says both RPM and power went up.

 

But the real problem I have is that I have no idea what you mean by "load". The definition I am familiar with is that the load on a motor is whatever system it is intended to drive. In this case, the power delivered to the rear wheel. Let's say the bike is on level ground. If anything changes to make the engine produce more horsepower, the result will be for it to accelerate until the load increases (not decreases) to absorb the additional horsepower. In this example, that will be in the form of increased rolling and wind resistance.

 

My guess is that the ECU is programed to sample barometric pressure on the fly, but as a lower priority than, for example, flywheel and TPS sensor positions, RPM, etc. If it only sampled on start up, it would not be able to compensate as one drove up and down mountains. That's the kind of problem which would generate lots of complaints, especially from riders buzzing around the Alps! The cure is simple enough.

 

We all agree that our system is not the most accurate, but we obviously disagree on terminology and how to improve it. Assuming what is meant by "load" is the conventional engineering definition of the effort the engine is applying, then sensing that can be done with strain gages on the driveshaft and other means. However, if the goal is to optimize mixture (I think we agree on that), then a mass flow sensor is superior because it is measuring that directly, rather than using load as an input to a model, which at best is going to be based on some assumptions.

[raz]

 

I'm puzzled by this debate and I suspect we'll all agree once we're talking about the same things. Anyway it has been very interesting, thanks to all of you! Not to say we should end it here

[Dan M]

Your wording was: "The change is small but the vacuum rises as does RPM because the power output of the engine also rises. What happens when power goes up? Load goes down."

 

It stands to reason that if more power is produced for a given throttle opening that RPM will rise. I was referring to the relationship of power vs load.

 

But the real problem I have is that I have no idea what you mean by "load". The definition I am familiar with is that the load on a motor is whatever system it is intended to drive. In this case, the power delivered to the rear wheel. Let's say the bike is on level ground. If anything changes to make the engine produce more horsepower, the result will be for it to accelerate until the load increases (not decreases) to absorb the additional horsepower. In this example, that will be in the form of increased rolling and wind resistance.

 

Right. From the beginning we've been talking about MAP & MAF sensors. My point was they sense engine load. Every link I've posted as well as what Emry posted, including BOSCH says they are load sensors.

I don't know how to explain it any further.

 

My guess is that the ECU is programed to sample barometric pressure on the fly, but as a lower priority than, for example, flywheel and TPS sensor positions, RPM, etc. If it only sampled on start up, it would not be able to compensate as one drove up and down mountains. That's the kind of problem which would generate lots of complaints, especially from riders buzzing around the Alps! The cure is simple enough.

 

 

We all agree that our system is not the most accurate, but we obviously disagree on terminology and how to improve it. Assuming what is meant by "load" is the conventional engineering definition of the effort the engine is applying, then sensing that can be done with strain gages on the driveshaft Huh? and other means. However, if the goal is to optimize mixture (I think we agree on that), then a mass flow sensor is superior because it is measuring that directly, rather than using load as an input to a model, which at best is going to be based on some assumptions.

 

I don't know that we can improve our system. The comparison was to more sophisticated systems with more sensors. Sensors that allow it to adjust for variables that our system can't.

Why would they use other means? Evidently all the major manufacturers think MAP and MAF technology are currently the best way to go, but what do they know? Can you tell me of any modern feed back system that does not use a MAF or a MAP? You have contended from the beginning that they are not needed for proper fueling. Why would all of the manufacturers develop this and use it?

I think we've pretty much beat it to death.

 

Note for Tomcat. Leave the regulator disconnected. Do you see what you started?

[Ryland3210]

Note for Tomcat. Leave the regulator disconnected. Do you see what you started?

 

I was only pointing out that with a smart and fast enough ECU equipped with a model (it would have to be pretty sophisticated), one could achieve accurate mixtures without an MAP sensor. Since you're absolutely right about the alternative manufacturer's have chosen, namely to use more sensors, my conclusion is that they do that because they have not been able to create a reliable and accurate enough firmware model to eliminate them. Mine example was a mental exercise, not something I have actually seen done.

 

Sensors based on strain gages applied to driveshafts has been off the shelf technology for many years.

 

Yes it was a guess on my part that barometric pressure is sampled on the fly, because I do not know that for a fact. However, I consider the alternative of only sampling it on startup extremely unlikely.

 

It's been fun, but I'm done too, unless you come up with more questions.

[Guest ratchethack]

It's been fun, but I'm done too, unless you come up with more questions.

I ran meself clean out o' stock way back when. . .

 

Though I admit it's been another veritable slice o' heaven for me, too. . .

 

Wot was it somebody said back in post #13?:

Frankly, I b'lieve it's a decent tee shot down the fairway beyond wot any such analysis might reasonably be expected to produce that's much of any value.

 

But -- and as aways -- TJM, & YMMV

[quazi-moto]

Aside from all the science (smoke & mirrors, perhaps??) am I safe to ride the bike with the FPR port vented to atmosphere?

[luhbo]

Totally!

 

How much risk would be induced by dealing with your avatar, eh?

 

Hubert

[quazi-moto]

How much risk would be induced by dealing with your avatar, eh?

 

Hubert

 

LOL!

[Onibaka]

Hi all.

I'll update this thread so I don't create a new one.

Recently, on the go, the motorcycle began to stall and lose power, I thought it was a problem with the TPS, but then I heard how, after the engine was turned off, fuel began to drain into the tank.

As I understand it, the fuel pressure regulator does not hold.

I took it apart and found pieces of some kind of plastic.

I have no idea what it is or how it got there.

Could it have been something inside the regulator originally and it fell apart?

[Lucky Phil]

5 hours ago, Onibaka said:

Hi all.

I'll update this thread so I don't create a new one.

Recently, on the go, the motorcycle began to stall and lose power, I thought it was a problem with the TPS, but then I heard how, after the engine was turned off, fuel began to drain into the tank.

As I understand it, the fuel pressure regulator does not hold.

I took it apart and found pieces of some kind of plastic.

I have no idea what it is or how it got there.

Could it have been something inside the regulator originally and it fell apart?

Plastic or rubber? Rubber would be fuel hose lining and plastic would be from the pump. It's not from inside the reg.

Phil