22.4 a/f on deceleration?
Jun 28, 2008, 07:04 AM
#32
eh? Are you deceling with the gas pedal depressed?. lift off=decel. Also, I'm somewhat referring to the overrun area of the fuel map that the ECU passes through when you lift off the gas pedal. If your popping on decel it's rich.
Last edited by Mr. Evo IX; Jun 28, 2008 at 07:07 AM.
Jun 28, 2008, 08:14 AM
#33
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This condition only happens with you off the throttle, (throttle position is at idle).
For the last time the injectors are not firing during a negative load condition. If you define "running" as the engine being powered by fuel being injected then the car is not "running" during this. The engine is not running on air alone. It is being driven by torque the drivetrain is providing. No there is no small amount of being injected during this time. The injectors do not fire until, like I said, until the this condition begins to affect idle. The injectors will then command an injector pulse width to maintain your closed loop fuel ratio. Of course this will only do so much in a gasoline powered vehicle. If the negative torque from the drivetrain is too great you will stall your engine.
Now in a diesel you have the same thing under a negative load condition. However when you approach idle in a diesel you are in speed control and the ecu will keep commanding more and more fuel (thus increasing torque) to maintain idle speed or at least try to. You can still stall the engine but it is harder to.
I do not understand why this is so hard to believe. This should be more believable (not considering the facts of course) than the "injects only very little fuel" reasoning. In an engine not designed for it, I don't think you have a chance to ignite the "very little" amount of fuel you think you are injecting. Depending on the injection method (Evo being multi-port) you are only able to ignite an a/f mixture of a certain amount. Of course I admit I do not know what amount this is in the Evo but I doubt it is at or greater than 20. So even if the engine was injecting a small amount fuel (even though it is not) you would not be able to ignite the very lean mixture. In that case the car would not be "running" either. Case closed.
Now with a direct injected engine you are able to created locally rich areas in the cylinder around the spark plug to ignite an overall lean mixture (total amount of fuel injected into the cylinder). However even in direct injected engines you are not injecting fuel under a negative load condition.
For the last time the injectors are not firing during a negative load condition. If you define "running" as the engine being powered by fuel being injected then the car is not "running" during this. The engine is not running on air alone. It is being driven by torque the drivetrain is providing. No there is no small amount of being injected during this time. The injectors do not fire until, like I said, until the this condition begins to affect idle. The injectors will then command an injector pulse width to maintain your closed loop fuel ratio. Of course this will only do so much in a gasoline powered vehicle. If the negative torque from the drivetrain is too great you will stall your engine.
Now in a diesel you have the same thing under a negative load condition. However when you approach idle in a diesel you are in speed control and the ecu will keep commanding more and more fuel (thus increasing torque) to maintain idle speed or at least try to. You can still stall the engine but it is harder to.
I do not understand why this is so hard to believe. This should be more believable (not considering the facts of course) than the "injects only very little fuel" reasoning. In an engine not designed for it, I don't think you have a chance to ignite the "very little" amount of fuel you think you are injecting. Depending on the injection method (Evo being multi-port) you are only able to ignite an a/f mixture of a certain amount. Of course I admit I do not know what amount this is in the Evo but I doubt it is at or greater than 20. So even if the engine was injecting a small amount fuel (even though it is not) you would not be able to ignite the very lean mixture. In that case the car would not be "running" either. Case closed.
Now with a direct injected engine you are able to created locally rich areas in the cylinder around the spark plug to ignite an overall lean mixture (total amount of fuel injected into the cylinder). However even in direct injected engines you are not injecting fuel under a negative load condition.
Jun 28, 2008, 12:00 PM
#34
I dont understand negative load. What are you referring to? vacuum?
The fuel map is scaled absolute pressure vs rpm 0-300kpa (IX). I think on decel the ECU cuts fuel to idle amounts (or what you have in your fuel map).
Maybe the ECU logic cuts fuel 100% and that would make sense too. Honestly I'm not sure how it functions but I know you can create antilag type effects with the stock ECU and I think you retain injection control on decel - but maybe it's just ignition control.
The fuel map is scaled absolute pressure vs rpm 0-300kpa (IX). I think on decel the ECU cuts fuel to idle amounts (or what you have in your fuel map).
Maybe the ECU logic cuts fuel 100% and that would make sense too. Honestly I'm not sure how it functions but I know you can create antilag type effects with the stock ECU and I think you retain injection control on decel - but maybe it's just ignition control.
Last edited by Mr. Evo IX; Jun 28, 2008 at 04:32 PM.
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Jun 28, 2008, 04:55 PM
#41
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If you didnt know this, you should refrain from any tuning or widebands all together. Sorry, but this is something you should have known for a while now.
Jun 28, 2008, 06:00 PM
#42
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im still learning..im not trying to tune anything yet as i want to make sure i understand something before i go and try adjusting it. everyone was a beginner at some point
Jun 29, 2008, 09:31 AM
#43
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I would define a hill as an event where road conditions are causing you to speed up but you would like to maintain the speed you had. In that case to maximize fuel mileage you want to utilize all the engine braking you can. Now if you would like to speed up going down the hill why on earth would you be engine braking? If you are not bound by speed limits or safety you can gain fuel mileage by coasting down a hill at idle. In that case you just let the car speed up however fast you would like and then of course you can use engine braking to maintain speed/slow down if you get going too fast for your liking.
Jun 29, 2008, 10:10 AM
#44
