JH600 stalling

[euphonius]

I know people are going on the 'bike is too lean tangent' which is highly logical and plausible. But shouldn't EFI systems be able to adjust for it? Also shouldn't a Bosch EFI system work as well if not better than the industry standard, and shouldn't it be easy to achieve with a 600 single, being a fairly simple and well known design?

This is only a theory, but maybe this could be an electronics issue and the spark is too weak? We all know Chinese shops don't adequately trickle charge new batteries overnight, we know that a company like Jialing might have mediocre wiring and that the ignition coil and leads might also be causing the problem. Just a theory to eliminate.

Dear Z,

Your reasoning is sound. There could also be significant quality control variance between individual bikes, given that they are essentially hand made in monthly batches only after customer orders have arrived. This would explain the wide variation in stalling between individual JH600s.

I do have stalls, though not nearly as bad as others (knock wood), as I approach 10k km on the bike, my engine and EFI are completely original save for an NGK plug and the aftermarket Laser can.

You'll recall that when you and I rode through Qufu in summer 2010, under incessant torrential rains, my JH600 was fearless, even in deep floodwaters that sometimes reached my knees. Did Jialing buy a better grade of copper wire when they assembled my bike, and Barry's?

I do like the way this is putting Jialing on the spot. Making motorcycles is an adult activity, and requires a certain minimal level of corporate responsibility.

cheers!

[ZMC888]

Euph, yes your bike was indeed faultless during torrential rain.

Could be a bad batch of leads, coils, EFI, sensor reading wrong, could be EFI itself, a question for a real engineer. Needs a BMW or Bosch engineer from Germany or Austria, I'm sure they'd find the problem in five minutes with the correct apparatus.

If it was my bike I'd try:

1. Make sure I had a Japanese manufactured NGK spark plug of the correct rating and gap measurement.
2. Buy a new internationally known brand battery and long charged it properly before I used it.
3. Change the lead to an NGK.
4. Try running Shell 97 octane.
5. Try changing the fuel filter if possible.
6. Try chevron techron fuel system cleaner or BG 44K
7. Try rewiring electrical system better
8. Try an aftermarket air filter and muffler to see if increased air flow actually helps.

after that I'm stumped, and would clearly be a Jialing company issue.

[Barry]

Same here, I was totally drenched twice but the bike just kept going! Engine/EFI wise my bike is still original as far as I know apart from the spark plug. About to hit 26k km.

[euphonius]

....About to hit 26k km.

Did you say 26k clicks???? OMG, I'm in awe! How much of that was on the clock from the previous owner?

[Barry]

Did you say 26k clicks???? OMG, I'm in awe! How much of that was on the clock from the previous owner?

9,5k from the previous owner, so I'm hoping to hit 17k clicks before it gets really cold.

[998S]

Well, for all of you who are really fed up with the Bosch black box already .... http://www.mychinamoto.com/forums/sh...p?3708-efi-kit
It is going to be a long cold winter anyway

[MotoKai]

My fuel injector fuel line came loose while riding back home. Gasoline was pouring out from the right side all over the engine and creating a Sinopec puddle on the street. After a tow in the rain by euphonius to a Honda/Jialing repair shop, we got it sorted out and the mechanic put on a new hose clamp.

Riding back home I experienced ZERO stalls. This was a big contrast to recent days of riding where I was getting downshift stalls at 1-in-4 intersections (very frustrating). So today I went out for a 70km ride to put her to a real test. Aside from a couple of Idle Stalls (while sitting at the intersection), I only experienced 2 Downshift Stalls - Why?

When working with the mechanic on the hose clamp fix, it was interesting to see the fuel injector jerk thru the hose with the original camp. Actually pushing the hose off the EFI nozzle. The fix was a replacement clamp that has a screw tightener to keep it fixed.

What's this all mean? Well, while perhaps there is a "mapping" issue with the ECU, maybe there is a mechanical issue with this factory setup? Food (ice cream) for thought.

BTW: Found some interesting literature on EFI that I found very informative. I'll post it here for you all.

[MotoKai]

EFI Basics, from NightRider.com

In its simplest terms, an electronic fuel injection (EFI) system is a computer controlled fuel delivery system. This electronic control unit (ECU) reads various sensors located on the vehicle and makes the determination of how much fuel to allow the engine to have based on this information. The computer will open and close the injectors allowing gasoline into the engine based on the sensor inputs and the fuel map programmed into the computer. The various sensors (RPM, engine temperature, air temperature, throttle position, manifold pressure, crankshaft position) provide information on operating conditions and load on the engine. Figure 1 is a detailed drawing of a typical fuel injection system and the sensors that might be in place. The EFI Components table provides a detailed description of each of the major components.

We will limit our discussion to the types of fuel injection systems that are likely to be encountered on motorcycles. One of the major differences between fuel injection systems is how the sense the amount of load that is placed on the engine. The load can be sensed by how far the rider has twisted the throttle and MAP (manifold absolute pressure). EFI systems that sense engine load by the use of the throttle or TPS (throttle position sensor) are referred to as an Alpha-N system. EFI systems that sense engine load by the use of a MAP sensor are referred to as a Speed-Density system. Harley-Davidson has used both types of EFI systems on its vehicles. While many of the sensors can be the same in both types of EFI systems, there is a significant difference in the way that each system determines what the load on the engine actually is. The Magneti-Marelli system used on EVO and Twin Cam FLH's until 2001 and Buell XL engines is an Alpha-N EFI system. On these bikes, load sensing is determined by the throttle position. The newer Delphi EFI system used on current Twin Cam engines is a Speed Density system. Speed Density EFI systems determine the engine load based on the intake manifold vacuum.

Why are there different types of EFI systems?

There are benefits to each of these types EFI system. We aren't even going to consider some of the other types of EFI systems currently available since we are only discussing V-twin engines. The choice of systems can be dependent upon the type of vehicle and its usage.

In the case of the HD Magneti-Marelli EFI system, the simplicity of using the throttle position sensor (Alpha-N) for determining engine load was probably the determining factor in using this for the first OEM EFI system.

A Speed Density EFI systems need a steady vacuum signal from the MAP sensor for the ECU to accurately determine the fuel mixture. If you have ever tried to read a vacuum gauge connected to a v-twin engine and watched the needle bounce around, you might begin to understand why a Speed Density EFI system was not the first choice for Harley-Davidson, engines with long duration cams or individual intake runners. Despite what appears to be an insurmountable problem with creating steady vacuum readings, there are a multitude of mechanical and electronic ways to "calm" the MAP reading for the ECU to use. The Delphi EMS system is able to use the manifold pressure from the HD intake, allowing it to more accurately determine the load on the engine based on the actual vacuum in the manifold rather than the position of the throttle. The Delphi unit also offers a level of sophistication and an ability to customize fuel maps in the field.

EFI Components Descriptions

To help you understand EFI, here is a table of technical terms commonly used and an explanation of the term along with some useful information. Along with the definitions, there are some simple graphics to further explain fuel injection systems. Click here to view EFI terminology

Fuel System Diagram

The fuel system diagram provides a simplified view on how fuel flows within an EFI system. The fuel tank supplies gasoline to the fuel pump. The fuel pump can be located in the fuel tank or external to the tank. The fuel pump provides a high pressure feed to the fuel rail that contains the fuel injectors. On the fuel rail there is a pressure regulator that limits the fuel pressure to 39-45 PSI and maintains a constant pressure. The pressure regulator has a vacuum line that connects it to the intake manifold. Any excess fuel leaves the pressure regulator and is returned to the fuel tank.

EFI Electronics and Sensors Diagram

The electronics and Sensors diagram is typical wiring diagram for an EFI system. Some EFI systems may have more or fewer sensors than this drawing. This represents a typical fuel injection system. The engine and air temperature sensors are simple devices that change in resistance as the temperature changes. The MAP and TPS sensors provide a 0-5 volt signal back to the EFI system depending upon the amount of pressure in the intake or the position of the throttle. The Oxygen Sensor provides a 0-1 volt signal back to the EFI system depending upon the air/fuel ratio at the exhaust. The injectors have a 12 volt power supply to them at all times. The ECU activates the injectors by switching the voltage to ground. The idle solenoid is activated by a 12-volt signal and allows additional air into the intake manifold to increase the idle RPMs. The main relay is activated by the ignition switch and provides power to all components in the EFI system. The fuel pump relay is activated by the EFI ECU when the engine is running. If the engine stalls, the ECU will deactivate the relay and shut the fuel pump off as a safety feature.

In this drawing the coil or tachometer signal represents the EFI "trigger" signal. In the case of a sequential injection system like the Harley-Davidson EFI systems, this would be Crank Position Sensor.

How does an EFI really work?

In is time to try to explain what is happening in the ECU now that we have confused you with a lot of rhetoric, diagrams and tables. While the real details of what is happening is very complex, we are going to present a greatly simplified version of what the computer happens.

1. The computer determines the current RPM of the engine based on input signals from the Crank Position Sensor.

2. The computer determines the load on the engine by checking the Throttle Position Sensor or MAP sensor.

3. The computer takes the RPM and Engine Load information to look in the Fuel Map table located in the ECU. While an actual fuel map has more values in it than the sample map in Table 2, a real table looks very similar to the simplified map shown. In our example, the number in the table represents the duty cycle of the injector, or what percentage of the time is the injector actually open and allowing fuel to flow. If the computer can not find exact matches to the RPMs and Engine Load, it is able to estimate the required value by looking at the values just higher and lower to calculate the needed value. For example if the engine is running at Wide-Open Throttle at 3900 RPMs, it calculates the fuel value to be 44 that is half way between 33 and 55.



4. Now that the computer has the main fuel value, it needs to determine if any "adjustments" to the fuel map value are needed.

5. The computer determines the engine temperature. If the engine is cold, then the fuel number is adjusted up by a pre-determined percentage. For example when the engine temperature is a 30 degrees F, the computer knows the engine is cold and needs more fuel, just like a choke on a carburetor. The computer looks up an engine temperature adjustment percentage that could be 20% (see table 3). If our previously looked up fuel value was 44, the computer now adds 20% to that number resulting in a new fuel value of 53. As the engine warms up, these adjustment percentages become smaller and at normal operating temperature the value is zero.

6. The computer determines the ambient temperature of the air entering the intake by reading the Intake Air Temperature sensor. As with the engine temperature adjustment, the computer will look up the percentage adjustment. Lets go back to our full throttle acceleration at 3900 RPMs and assume our engine has warmed up to normal operating temperature, but the outside air temperature is 90 degrees F. The computer looks up an adjustment percentage of -2% (see table 4).

The computer actually understands that at high air temperatures, the engine requires less fuel so it leans the fuel value down from 44 to 43. If the air temperature had been cold, the fuel mixture would have been made slightly richer.

7. The computer has now determined that at Wide Open Throttle, at 3900 RPMs, normal engine temperature and a 90 degree air entering the intake that the engine needs to keep each fuel injector open 43% of the time.

4. The computer now checks to see if it is time for the fuel injector to be activated. When it is time for the fuel injector to open, the computer allows current to flow through the injector for the required amount of time. The opening time can be controlled very precisely, down to the millisecond.

As you can see, the computer in a fuel injection system is doing a lot of things very quickly. While some EFI systems do more than listed above, the description above is a rough idea of the minimum amount of work the system actually has to do. The real activities are much more complex than explained, but you get the idea that your EFI ECU is pretty good at knowing how much fuel your engine really needs.

[998S]

When working with the mechanic on the hose clamp fix, it was interesting to see the fuel injector jerk thru the hose with the original camp. Actually pushing the hose off the EFI nozzle. The fix was a replacement clamp that has a screw tightener to keep it fixed.

Yeah, food for thought ...
For my right understanding; from above, I guess your fuel line from the pump (in the tank) to the injector came loose, right?
Then you saw the pressure from the pump into the hose. That should be smooth, high pressure though, not pulsing.

But besides of the lean mixture (I stay with that one for sure right now), I start to think more and more that there is a glitch in the ECU.

[998S]

Ok, here are the thoughts after a night mulling over it ... I admit it is a long-shot, but the only thing I can come up with so far. Please shoot at it...

The Jialing might have smaller then normal injection diameters or lower then normal fuel pressure.
Several of you mentioned that the stalling problem gets worse over time.

Imagine that, due to bad fuel, the fuel filter is partly blocked, reducing the fuel flow. The bad fuel might also gum up your injector, causing the injector getting (partly) blocked.
This together will allow less fuel to be injected, causing a leaner mixture. That, in combination with an already lean-set mixture by the manufacturer, might just be too lean in some occasions, resulting in the stalling.

Then, Motokai blew the hose, a strong free flow of fuel went from the tank, through the pump, through the filter, out of the hose.
This might have cleaned things up temporarily, resulting in a slightly richer mixture, resulting into less stalls.

Do you guys ever use injection cleaner in your bike (the small bottles which you can add to the fuel while filling-up)?