fuel pressure

[RPG]

Hopefully I can test out my new theory soon, but am wondering how the fuel pressure is regulated/maintained in a '04 RT. Have had some issues starting last summer with low idle stalling.

 

Is the pump supposed to run continuously while the engine is running or does it only cycle on/off depending on what the Pressure Regulator is doing? I'm assuming that the Pressure Regulator is just a spring loaded device used to maintain a preset PSI on the whole system?

 

I'm asking because I've changed quite a few parts since the trouble occurred. Bike runs fine until warm and then constantly stalls only at idle or runs rough below 2,000 rpm. All vacuum lines and vacuum hoses checked to the tank. Everything appears to be venting properly.

 

Replaced both stick coils, replaced O2 sensor and thoroughly cleaned and inspected throttle bodies. (45k)

 

I've since removed the Cannister and associated hoses just to see if the cannister might be causing the problem since I've admittedly over-filled the bike since new.

 

Hopefully I can take a test ride this weekend and see if just the cannisterectomy was the root cause. If not, I think I'm looking at fuel system components.

 

thanks,

 

RPG

[ESokoloff]

....Bike runs fine until warm and then constantly stalls only at idle or runs rough below 2,000 rpm....

Faulty temp in the air box?

 

As far as the pump, I believe it runs all the time & would be more likely to cause a problem at hi rpm/load then at low idle/load.

[Boffin]

The pump runs for a short burst every time the HES triggers, so when the engine is running the pump is continuously running, but stops if the engine stalls.

The pressure regulator is behind at the back of the engine and the bike needs to be stink-bugged to get it out, so try fitting a t-hose to the fuel line and measuring the pressure, which should be 3-bar (43.5 psi)

 

Andy

[Peter Parts]

Do discern if one or both cylinders.

 

Idle speed too low?

 

Ordinarily, you'd check whatever influences the fueling at low speeds. That would be the TBs but I'd think they wouldn't both be wonky together unless you tuned 'em funny... which is easy to do and hard to detect unless you test-drive the synch under load with vacuum gauges which reveal the truth better than anything else.

 

Fuel delivery doesn't sound relevant. Fault, if any, might be injectors which have to be cleaned by miles and by years of use. See my write-up at URL below.

 

Ben

dripping for days in Toronto

[Tobias]

The fact that it runs well cold and then stalls when warm makes me agree with ESokoloff in that it is likely a temp sensor going out.

I believe there are both air temp and an oil temp sensors in this configuration.

When the engine is cold the Motronic is running in "open loop" mode where it doesn't take any feed back from the sensors and runs in a pre-programed mode.

When the engine is warm the Motronic switches to "closed loop" mode and uses input from each of the sensors to control the ECU.

If RPG has a faulty temp sensor throwing bad information to the ECU it won't show up until the engine is warm.

[RPG]

thanks for the great input guys. I've measured the air temp and oil temp sensors before in the past to get a sense of their resistance algorithims related to heat but it's been a few years. Have a thermal chamber at work so should be easy to test.

 

I don't think it's fuel related either but just going back to what I did last before all this started. A tranny lube, which had me moving the fuel regulator out of the way to pull the tranny. Doubt that moving it a few inches would cause an issue but stranger things have happened in the world of mechanics.

 

RPG

[dirtrider]

---When the engine is cold the Motronic is running in "open loop" mode where it doesn't take any feed back from the sensors and runs in a pre-programed mode.

When the engine is warm the Motronic switches to "closed loop" mode and uses input from each of the sensors to control the ECU.

If RPG has a faulty temp sensor throwing bad information to the ECU it won't show up until the engine is warm.

 

Morning Tobias

 

Actually you have that kind of backwards.

 

In open loop the fueling on the 1100/1150 is based on all the sensors except the 02 sensor. The main (re quick rough) fueling is based on fixed mapping that is based first on the TPS (throttle position sensor) and engine RPM (both main players). That QUICKLY gets the rough fueling in the ballpark. From there the fueling is continually and actively TRIMMED either richer or leaner by the barro sensor (altitude), oil temp sensor (this is probably the largest trim factor), and IAT (intake air temp).

 

In closed loop the fueling is ONLY based on the 02 sensor feedback. That is why it is called CLOSED LOOP. The fueling loop is closed to only between the fueling computer and the 02 sensor. Seeing as the 02 sensor is a narrow band it is only capable of holding the fueling to a very narrow fuel air ratio band so no need or use for other sensors. Now that doesn’t mean the other sensors simply go to sleep as they are quickly needed anytime the system pops open loop due to quick throttle movement, high RPM, or other. The other sensors are also used to effect active engine ignition timing trim even in closed loop

 

Of the above sensors the TPS has the largest influence on fueling control with oil temp next, then the barro (altitude), the IAT(air box sensor) has very little effect on main fueling control. The altitude sensor has a fair amount of fueling control but is also non linear in it’s control direction to prevent converter damage if it fails. It is set up to allow fuel enleanment as the altitude goes up but pretty well chopped at around (–1000’) in the fuel enrichment direction. This is not a problem as nobody I know rides a motorcycle at altitudes much below a 1000 ft below sea level.

 

[dirtrider]

Morning RPG

 

Yes, definitely ride it for a while to see if it is still acting up.

 

As mentioned above the fuel pump is a “constant run” “fixed displacement” pump with the pressure regulation being controlled by a spring loaded regulator using altitude compensation. It regulates by simply returning by-pass fuel back to the gas tank. This type of pressure regulator is pretty fool proof and seldom fails (except leaks).

The one down side of this type of pressure regulator is it just won’t/can’t regulate if the return hose is blocked or plugged.

 

A good quick check to see if your pressure regulator is allowing ENOUGH fuel rail pressure is to ride the bike at very high speed. It the bike will run out at 120 mph+ it is getting enough fuel flow at enough pressure.

 

On your stalling problem? My first guess would be 02 sensor but seeing as you have already replaced that then it is probably something else.

 

You can quickly check the IAT (air sensor in the air box) by disconnecting it in warm weather. When disconnected the fueling computer sees it is out of operational range and substitutes a nominal value somewhere around 70°f as the base value. These things (IAT’s) very seldom cause a problem as they are about as reliable as a paper clip. If you really have the need to check it in colder weather simply unplug it then purchase a little 4.5K or 5K ¼ watt resistor and plug that into the removed plug. That will emulate about 0°f to 30°f ambient temps.

 

On your stalling problem—If it still stalls see if you can get someone to follow you for a while. Have them watch your exhaust at stall. Just as it stalls see if they notice black smoke from either one side or the other.

 

Maybe setting your idle to the high side will help. I used to set my old 1100R to just a bit above recommended to prevent “snap closed throttle stall” that could randomly appear until warm.

 

[Peter Parts]

Dirtrider's opinion about O2 sensing is perfectly applicable to cars but does not describe the Motronic, as I have observed it. I don't think it actually does much at all except on long, surging-inclined super-slab rides.

 

Anybody can disconnect their O2 sensor and see that their bikes feels the same with or without... except no surging.

 

In any case, the 3-or-more wire O2 sensor is at nearly full operating temperature in maybe a quarter of a mile. Esp. in cold weather, that is far before the oil temp sensor has barely moved (and of course, the IAT doesn't change, eh). Anyone who disputes that has not actually measured the O2 sensor voltage output as I have.

 

Is your problem within that scale of time or distance?

[dirtrider]

Dirtrider's opinion about O2 sensing is perfectly applicable to cars but does not describe the Motronic, as I have observed it. I don't think it actually does much at all except on long, surging-inclined super-slab rides.

 

Anybody can disconnect their O2 sensor and see that their bikes feels the same with or without... except no surging.

 

In any case, the 3-or-more wire O2 sensor is at nearly full operating temperature in maybe a quarter of a mile. Esp. in cold weather, that is far before the oil temp sensor has barely moved (and of course, the IAT doesn't change, eh). Anyone who disputes that has not actually measured the O2 sensor voltage output as I have.

 

Is your problem within that scale of time or distance?

 

Afternoon Peter

 

Even when the 02 is up to heated temperature it still doesn’t get used by the Motronic, even if putting out a usable voltage, until a certain oil temp and/or given run time after start. This usually happens within a mile or so on mild weather ride off.

 

Until actually using the 02 signal the Motronic will place a fixed .5 volts on the 02 signal circuit (that will look like an 02 output to an uniformed person using a meter). Until all the set parameters are met the 02 signal will be fixed at .5 volts or to one side or the other .5 volts (no cross counts)

 

Once the 02 voltage starts varying (toggling across the .5 volt mid point) then that means the Motronic is using the 02 signal. That is REAL easy to see with high impedance voltmeter.

 

 

 

[RPG]

thanks guys, of course the weather didn't cooperate this weekend, but we DID get my buddy's R90s running after a 10 year nap!

 

I forgot to mention that I also verified the Hall Effect sensors checked out perfect. And sustained riding at 110+ last fall appears to indicate the fuel regulator is fine. So, we'll go from there.

 

RPG

[RPG]

Still crappy weather in the Detroit area, but I did hook up the GS911 diagnostic tool to my '04 RT and got her warmed up in the garage (5 bars) Both the oil temp (Engine Temperature)and Intake Air Temperature appear to be working, according to the "Realtime Values" monitoring per the GS911. Engine temp climbs to about 90C when 5 bars are displayed. To increase Intake Air Temp, I just plugged in a hair dryer and focused on the Intake temp sensor and verified it rises and falls.

 

Maybe, maybe today I can take for a ride. Supposed to be a balmy 50F with no snow!

 

thanks,

 

RPG

[Peter Parts]

Dirtrider's opinion about O2 sensing is perfectly applicable to cars but does not describe the Motronic, as I have observed it. I don't think it actually does much at all except on long, surging-inclined super-slab rides.

 

Anybody can disconnect their O2 sensor and see that their bikes feels the same with or without... except no surging.

 

In any case, the 3-or-more wire O2 sensor is at nearly full operating temperature in maybe a quarter of a mile. Esp. in cold weather, that is far before the oil temp sensor has barely moved (and of course, the IAT doesn't change, eh). Anyone who disputes that has not actually measured the O2 sensor voltage output as I have.

 

Is your problem within that scale of time or distance?

 

Afternoon Peter

 

Even when the 02 is up to heated temperature it still doesn’t get used by the Motronic, even if putting out a usable voltage, until a certain oil temp and/or given run time after start. This usually happens within a mile or so on mild weather ride off.

 

Until actually using the 02 signal the Motronic will place a fixed .5 volts on the 02 signal circuit (that will look like an 02 output to an uniformed person using a meter). Until all the set parameters are met the 02 signal will be fixed at .5 volts or to one side or the other .5 volts (no cross counts)

 

Once the 02 voltage starts varying (toggling across the .5 volt mid point) then that means the Motronic is using the 02 signal. That is REAL easy to see with high impedance voltmeter.

 

 

 

Could I be that "uninformed person" you refer to?

 

All I can say is that I have every recollection of it not working that way. If it did, the voltage on my 3+-digit meter would go to .5 and stay there for a while and I just might notice it, on a good day.

 

For sure, seems very peculiar way for software to work by "place a fixed .5 volts on the 02 signal circuit" when the O2 sensor is a generator and other obvious circuit-design reasons, etc.

 

Why ever would it do that instead of some software "switch"?

 

BTW, if your model is correct, then the IAT spoofers would permanently cut-out the O2 sensor and closed-loop operation. Of course, maybe that is really how they work. What do you think?

 

Ben

[dirtrider]

Afternoon Ben

 

Well if the fueling computer DOESN’T place a nominal middle voltage (actually .45v but we usually round it off to 5v for conversation) on the inactive 02 sensor until it reaches it’s operational temperature of slightly over 600° what keeps the fueling computer from commanding the fueling to go richer, & richer, & richer, & richer yet, etc as the cold 02 sensor would have little or no voltage output therefore showing the computer a (continually) lean signal?

 

If the fueling computer’s after start-up time-out timer says OK on using the 02, and the oil temp says engine hot enough to use the 02, but the 02 is still below 600° you have a real fueling control issue to deal with. But, with a nominal .45 volts on the 02 signal line that tells the computer neither lean or rich (so it doesn’t respond either way). An operational 02 sensor never stays at .45 volts for more than a nano second so the computer knows the 02 isn’t heated and ready to use yet.

 

That .45 volts is very/very low load circuit and you probably won’t even see it as .45 volts without a very high impedance voltmeter. What you will usually see is a voltage change or upwards voltage fluctuation on a cold 02 signal circuit when the key is just turned on.

 

BTW, if your model is correct, then the IAT spoofers would permanently cut-out the O2 sensor and closed-loop operation. Of course, maybe that is really how they work. What do you think?

 

I have no idea what the IAT (INTAKE air temperature) has to do with open/closed loop operation. The computer needs to know “engine temperature” to go closed loop but could care less about intake air temperature. For all it cares it could really be that cold outside.

 

[Peter Parts]

Your pedantry about .5 versus .45 volts doesn't hide the fact that you seem "uninformed" (to share the word you used to describe me earlier) about the totally screwball (it seems to me) concept of the ECU having some hard-wiring that actually puts out electrons into the wire that carries the O2 signal back to itself so that is can read an illusory voltage that it commanded to exist by itself!!! Maybe Bosch does it that way, but no sane designer would.

 

Thanks for your advice about not measuring O2 sensor voltages with a $5 VOM. Always great to learn something new (wish I knew how to insert emoticons). Surely I am at fault for not conveying to careful readers like yourself that I do have a certain modest grasp of electronics, if not emoticons, and do not post opinions flawed by elementary errors in measuring stuff*.

 

I guess you have not been following the IAT spoofer discussion. Let me draw the connection for you more fully. You earlier suggested that there's no closed-loop operation until temperature sensors (oil, air??) get to some value. The IAT sensor spoofer permanently fools the ECU into thinking is it sub-zero out there and the dumb thing never varies.

 

Even though self-delusion about power increases is a major theme of bike modifiers such as the people who buy these vastly overpriced resistors, I still wonder if there is some possible basis for their enthusiasm for this form of snake oil... and possibly related to your claim described above (which, BTW, I never heard before and doubt if it is true of the primitive Motronics)

 

Ben

 

*OK, maybe not tooooo often.

[dirtrider]

Morning Ben

 

You are correct on one point and that is ONE of us is truly mis-informed and/or doesn’t understand how closed loop systems operate.

 

I’m just not going to argue this with you as nothing good can come from arguing at this point.

 

We got so far off the OP’s original question that it defines hijack.

 

I guess I am just going stop here and leave it up to the informed readers here on which one of us they want believe about how closed loop systems operate.

 

 

[AndyS]

I guess that closes the loop then!

[Jerry Duke]

Thanks for your info D.R. How you can keep from verbally slapping Peter / Ben is beyond me.

[RPG]

I guess now would not be a good time to ask how to ascertain if fuel injection spray patterns are correct.......

 

RPG

[dirtrider]

Afternoon Rick

 

On the injector testing. A visual on both sides being the same spray size and conical shape is about all you can do at home. If you want to test the output get two identical small containers (I make my own from clear PVC hose just a little larger than injector size about 8” long with a cork in the bottom of each one). The length is required so the fuel stays in the container when spraying. Then remove both injectors, place in the tube tops then crank the engine over. You should be able to watch the spray pattern and see if both sides place the same amount of fuel in both tubes. Run the test on a cold engine and at full choke to get a decent spray of fuel, if you open the throttle too far it could go into clear-flood-enable and shut most of the fueling off thinking your are clearing a flooded engine.

 

With your engine running OK and only an occasional stall I doubt anything will turn up by just watching the injectors spray. Maybe you can catch one not shutting off completely though.

 

The absolute best way to rule out the injectors is to try another known good set.

 

[Peter Parts]

Injectors need a shave and haircut by the mileage AND by the calendar. Authorized shops always test before and after including a judgment about spray pattern. Pattern matters as much as volume. Be sure to ask for a written test report. Pretty cheap too. See write-up at URL below.

 

The injectors are a weak-link in the Oilheads. You can buy matched aftermarket injectors from the class-act supplier.

 

Poor Jerry Duke.....