My Kawasaki ZX-14R's engine smoothness rivals smooth automobile engines. Honestly it's smoothness is impressive for a car. Amazing for a motorcycle. However it seems to run just a little less smoothly when the temperature of the fuel rises. For example after riding a while till the tank is well less than 1/2 full and you sit the bike. Engine heat is absorbed by the remaining gallon of fuel and, after 1/2 hour or so, get back on the bike and it runs slightly less smoothly. Anyone else have a similar theory?
Fuel temperature effects.
- Thread starter digitalSniperX1
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It might just be how the bike runs when it gets hot. Does it have the stock factory tune in it?.,,
All bikes still vibrate to some degree and the one thing to eliminate if you think you feel
more vibrations or hear an odd rattle is a loose exhaust system because it will amplify any
of those vibrations to an annoying level... tap the pipes with the palm of your hand to test
if any bolts points or connections are loose... also check the foot pegs bolts and anything
bolted to the foot pegs...
more vibrations or hear an odd rattle is a loose exhaust system because it will amplify any
of those vibrations to an annoying level... tap the pipes with the palm of your hand to test
if any bolts points or connections are loose... also check the foot pegs bolts and anything
bolted to the foot pegs...
Yes and the bike isn't really hot. Just the fuel. When solar soaked does the same thing. I'm almost certain it's because of hot/warm gasoline.
Yeh and is far quicker to vaporize.
At warm/ hot temperatures, engines in closed loop operation are mapped increasingly lean for light loads. For a ZX-14 that probably means less than 120 mph, where the engine only has to make less than 25% of its maximum power, so rich fueling for additional CC cooling is really not necessary. And since Kawisaki Heavy Industries surely wants to play good citizen with (somewhat reasonable) fuel consumption and in-compliance exhaust emissions. But, in terms of NVH levels, lean mixture at low power levels can have a more grainy/ uneven character. Compound that with fuel temperatures outpacing the ambient air temperature the injectors likely are delivering an extra lean mixture because the gasoline reaches an unexpected low density, and FI mapping is calibrated on volume delivery, not mass delivery.
Me Not being an expert at all, and having said that, you provided what I'll call "best response ever." Thanks!
If it's in closed loop, then the computer should set it back in a handful of revolutions to where it should be.
If it's in open loop, Benoulli's equation would have the mass flow rate of fuel relatively insensitive to density on the straight mass flow to pressure regulation point.
If it's in open loop, Benoulli's equation would have the mass flow rate of fuel relatively insensitive to density on the straight mass flow to pressure regulation point.
Just to be clear though, engine temp could be low, while the fuel tank (flat black) can be get pretty high from baking in Florida sun. Still feel the same NVH effect. So the fuel's density/vaporization is probably causing the graininess I feel.
When engine is warm it too can heat the fuel after sitting, the fuel acting as a heat sink.
When engine is warm it too can heat the fuel after sitting, the fuel acting as a heat sink.
I thought for sure you were going to spring that one on the busy little shop.
http://www.pipeflowcalculations.com/pipe-valve-fitting-flow/flow-in-pipe.php
Would Benoulli's be the venturi calculator?
http://www.pipeflowcalculations.com/pipe-valve-fitting-flow/flow-in-pipe.php
Would Benoulli's be the venturi calculator?
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Ok by closed loop I'm assuming an O2 sensor provides feedback and the system measures the O2 in the exhaust and adjusts mixture accordingly to reach some stoichiometric assignment. So if the response to feedback is out of range ( in this case due to hot/low density gasoline), would the controller simply default to open loop? If this isn't a valid question, please excuse the fact I'm not an ME and not an engine controller designer, and tell me where my thinking is wrong.!
Haha and I'm a digital IC designer and some optics guys do not believe that's engineering and they say that while using a digital computer to do analysis.
Originally Posted By: digitalSniperX1
Ok by closed loop I'm assuming an O2 sensor provides feedback and the system measures the O2 in the exhaust and adjusts mixture accordingly to reach some stoichiometric assignment. So if the response to feedback is out of range ( in this case due to hot/low density gasoline, would the controller simply default to open loop? If this isn't a valid question, please excuse the fact I'm not an ME and not an engine controller designer, and tell me where my thinking is wrong.!
Open loop is typically the W.O.T. setting.
Closed loop is where it takes the O2 sensor and feeds it back into the algorithm to tune the air fuel ratio back to the desired number, usually lean. If the injectors flow less, the closed loop will open them up for longer to get the right answer.
The delco hackers down here have found that the supercharged 6 that Holden put in my Caprice runs out to 19:1 A/F on the highway...that's really lean, and encourages a lean misfre, and also leads to higher throttle openings for a given road load.
All part of trying to get economy by being lean, and reduced pumping losses (more throttle opening).
It takes a lot to throw things to open loop at light load, and that's usually a limp home scenario.
Ok by closed loop I'm assuming an O2 sensor provides feedback and the system measures the O2 in the exhaust and adjusts mixture accordingly to reach some stoichiometric assignment. So if the response to feedback is out of range ( in this case due to hot/low density gasoline, would the controller simply default to open loop? If this isn't a valid question, please excuse the fact I'm not an ME and not an engine controller designer, and tell me where my thinking is wrong.!
Open loop is typically the W.O.T. setting.
Closed loop is where it takes the O2 sensor and feeds it back into the algorithm to tune the air fuel ratio back to the desired number, usually lean. If the injectors flow less, the closed loop will open them up for longer to get the right answer.
The delco hackers down here have found that the supercharged 6 that Holden put in my Caprice runs out to 19:1 A/F on the highway...that's really lean, and encourages a lean misfre, and also leads to higher throttle openings for a given road load.
All part of trying to get economy by being lean, and reduced pumping losses (more throttle opening).
It takes a lot to throw things to open loop at light load, and that's usually a limp home scenario.
Originally Posted By: CentAmDL650
lean mixture at low power levels can have a more grainy/ uneven character. Compound that with fuel temperatures outpacing the ambient air temperature the injectors likely are delivering an extra lean mixture because the gasoline reaches an unexpected low density, and FI mapping is calibrated on volume delivery, not mass delivery.
Hmmmm ... Ill agree with the low density but not on the FI mapping. Owner is complaining about rough running which includes idling (low power).
80% of the time bikes run in closed loop mode, the O2 sensors adjust the fuel mixture and know exactly how much fuel is being burned. So even though the fuel is warm and less dense, the fuel mixture being delivered to the engine would be adjusted accordingly.
No different then if your at a high altitude or low altitude the engines electronic fuel management will adjust the A/F to burn the right mixture. Even to the degree or using the wrong octane fuel.
Just for fun, and for fun only, I would be curious if it would behave the same is gas without ethanol was used.
If I was the owner, I would go to the bikes forums and see if anyone else can confirm what he is saying, it could simply be a programming thing, taking into account different types of fuel? Or slight anomaly of the high performance engine if EVERYONE has the same issue.
lean mixture at low power levels can have a more grainy/ uneven character. Compound that with fuel temperatures outpacing the ambient air temperature the injectors likely are delivering an extra lean mixture because the gasoline reaches an unexpected low density, and FI mapping is calibrated on volume delivery, not mass delivery.
Hmmmm ... Ill agree with the low density but not on the FI mapping. Owner is complaining about rough running which includes idling (low power).
80% of the time bikes run in closed loop mode, the O2 sensors adjust the fuel mixture and know exactly how much fuel is being burned. So even though the fuel is warm and less dense, the fuel mixture being delivered to the engine would be adjusted accordingly.
No different then if your at a high altitude or low altitude the engines electronic fuel management will adjust the A/F to burn the right mixture. Even to the degree or using the wrong octane fuel.
Just for fun, and for fun only, I would be curious if it would behave the same is gas without ethanol was used.
If I was the owner, I would go to the bikes forums and see if anyone else can confirm what he is saying, it could simply be a programming thing, taking into account different types of fuel? Or slight anomaly of the high performance engine if EVERYONE has the same issue.
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Nope. If fuel pump is louder it'd likely be masked by wind noise.
Idle is actually fine. I feel it above 3k or so rpm.
Those reading should know the vibration increase is minimal and begins at 3500 rpm
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