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  #421  
Old 06-20-2013, 06:27 PM
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Im sorry I forgot to post this a month ago. The 52" XF1 and XF2 use the same exact factory high lift marbain blades.
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  #422  
Old 06-20-2013, 06:50 PM
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Quote:
Originally Posted by ProStreetCamaro View Post
The efi so far has been very nice. First start of the day when the engine is cold it will chug a little if you dont throttle it way up when you start to drive it. If you let it idle a minute to warm up it doesn't do it.
I find this strange, I've been running a Kohler efi since 2006 and I've never heard it run anything but perfect, and has always started at what seems instantaneously no matter the temperature cold or hot.

I can start the engine and within 5 seconds engage the blades at its idle rpm's, with it hardly changing sounds.

I find it odd that your efi would act cold, I've never seen this, and I've started mine at 20 while sitting in an open shed. The engine turned over and it was running perfectly, completely different from a carburetor type engine where you need to play with the choke.

My 35 Kawasaki cranks very good in cold weather, choke it, spin the engine maybe 3 times, push the choke down 75% and it's running, but it is no where comparable to the way my efi starts and runs.

TLS, you've had a great deal of experience with the Kohler 28 efi, and now your new Kohler BB with the Delphi system, how do they crank and act in comparison?
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  #423  
Old 06-20-2013, 06:56 PM
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Puppy does the Kohler EFI start in open loop? If so it would run a bit different until it goes into closed loop. I have never run one.
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  #424  
Old 06-20-2013, 06:58 PM
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Quote:
Originally Posted by GMLC View Post
Puppy does the Kohler EFI start in open loop? If so it would run a bit different until it goes into closed loop. I have never run one.
Yes, all efi's with closed loop starts in open loop, that's why I was confused about what Kawasaki said concering the hybrid system they spoke of.

This will explain EFI in detail:

The Electronic Fuel Injection (EFI) system is a
complete engine fuel and ignition management
design. The system includes the following principal
components:
• Fuel Pump
• Fuel Filter
• Fuel Rail
• Fuel Line(s)
• Fuel Pressure Regulator
• Fuel Injectors
• Throttle Body/Intake Manifold
• Engine Control Unit (ECU)
• Ignition Coils
• Engine (Oil) Temperature Sensor
• Throttle Position Sensor (TPS)
• Speed Sensor
• Oxygen Sensor
• Wire Harness Assembly & Affiliated Wiring,
• Malfunction Indicator Light (MIL)
Operation
The EFI system is designed to provide peak engine
performance with optimum fuel efficiency and lowest
possible emissions. The ignition and injection
functions are electronically controlled, monitored and
continually corrected during operation to maintain the
theoretical ideal or “stoichiometric” air/fuel ratio of
14.7:1.
The central component of the system is the Motronic™
Engine Control Unit (ECU) which manages system
operation, determining the best combination of fuel
mixture and ignition timing for the current operating
conditions.
An electric fuel pump is used to move fuel from the
tank through the fuel line and in-line fuel filter. A fuel
pressure regulator maintains a system operating
pressure of 39 psi and returns any excess fuel to the
tank. At the engine, fuel is fed through the fuel rail
and into the injectors, which inject it into the intake
ports. The ECU controls the amount of fuel by varying
the length of time that the injectors are “on.” This can
range from 1.5-8.0 milliseconds depending on fuel
requirements. The controlled injection of the fuel
occurs each crankshaft revolution, or twice for each 4-
stroke cycle. One-half the total amount of fuel needed
for one firing of a cylinder is injected during each
injection. When the intake valve opens, the fuel/air
mixture is drawn into the combustion chamber,
ignited, and burned.
The ECU controls the amount of fuel being injected
and the ignition timing by monitoring the primary
sensor signals for engine temperature, speed (RPM),
and throttle position (load). These primary signals are
compared to preprogrammed “maps” in the ECU
computer chip, and the ECU adjusts the fuel delivery
to match the mapped values. After the engine reached
operating temperature, an exhaust gas oxygen sensor
provides feedback to the ECU based upon the amount
of unused oxygen in the exhaust, indicating whether
the fuel mixture being delivered is rich or lean. Based
upon this feedback, the ECU further adjusts fuel input
to re-establish the ideal air/fuel ratio. This operating
mode is referred to as “closed loop” operation. The
EFI system operates “closed loop” when all three of
the following conditions are met:
a. The oil temperature is greater than 35C (86F).
b. The oxygen sensor has warmed sufficiently to
provide a signal (minimum 375C, 709F).
c. Engine operation is at a steady state (not starting,
warming up, accelerating, etc.).
During “closed loop” operation the ECU has the
ability to readjust temporary and learned adaptive
controls, providing compensation for changes in
overall engine condition and operating environment,
so it will be able to maintain the ideal air/fuel ratio of
14.7:1. The system requires a minimum engine oil
temperature greater than 55C (130F) to properly
adapt. These adaptive values are maintained as long
as the ECU is “powered up” by the battery.



During certain operating periods such as cold starts,
warm up, acceleration, etc., an air/fuel ratio richer
than 14.7:1 is required and the system operates in an
“open loop” mode. In “open loop” operation the
oxygen sensor output is not used, and the controlling
adjustments are based on the primary sensor signals
and programmed maps only. The system operates
“open loop” whenever the three conditions for closed
loop operation (above) are not being met.
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Last edited by puppypaws; 06-20-2013 at 07:03 PM.
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  #425  
Old 06-20-2013, 07:03 PM
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GMLC GMLC is offline
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Quote:
Originally Posted by puppypaws View Post
Yes, all efi's with closed loop starts in open loop, that's why I was confused about what Kawasaki said concering the hybrid system they spoke of.
Im just wondering if what PCS is feeling is when its still in open loop. Once in closed loop the computer is adjusting the fuel mixture based on actual readings. I don't know how advanced Kohlers closed loop system is or how long it stays in open loop?
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  #426  
Old 06-20-2013, 07:09 PM
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Puppy I just saw the additional info you posted, thanks. So it is a pretty advanced system. It doesn't appear to use heated oxygen sensors and that means it will stay in open loop for a few minutes before going into closed loop. I bet that is what PCS is feeling.
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  #427  
Old 06-20-2013, 07:15 PM
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puppypaws puppypaws is offline
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Quote:
Originally Posted by GMLC View Post
Puppy does the Kohler EFI start in open loop? If so it would run a bit different until it goes into closed loop. I have never run one.
I've only had experience with two Kohler efi engines, and they have both cranked and run to perfection. Maybe if someone reads this that understands open and closed loop a little better than me, they can explain how an engine with efi technology can start in open loop so much better than a carburetor type engine.

I guess it's possible they don't all start equally, and I have been fortunate to get two that has been exceptional. I would say the big blocks may start differently, and that is why I would like TLS to answer this question, he's had experience with both.
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  #428  
Old 06-20-2013, 07:20 PM
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ProStreetCamaro ProStreetCamaro is offline
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Quote:
Originally Posted by GMLC View Post
Puppy I just saw the additional info you posted, thanks. So it is a pretty advanced system. It doesn't appear to use heated oxygen sensors and that means it will stay in open loop for a few minutes before going into closed loop. I bet that is what PCS is feeling.

That is my guess a well. It runs smooth at first start but if I try to move the mower right away at anything less than half throttle it will chug a little. Not really a problem just an observation.
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  #429  
Old 06-20-2013, 07:21 PM
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Quote:
Originally Posted by puppypaws View Post
I've only had experience with two Kohler efi engines, and they have both cranked and run to perfection. Maybe if someone reads this that understands open and closed loop a little better than me, they can explain how an engine with efi technology can start in open loop so much better than a carburetor type engine.

I guess it's possible they don't all start equally, and I have been fortunate to get two that has been exceptional. I would say the big blocks may start differently, and that is why I would like TLS to answer this question, he's had experience with both.
Even when in open loop EFI is still waaay more precise than a choke covering a carb venturi. The computer still uses some data from sensors in open loop just not the oxygen sensors.
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  #430  
Old 06-20-2013, 07:23 PM
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Oops I keep calling PSC, PCS sorry....
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