Engine Control - Revision history

SpookySimon: /* Active */ formatting and unorphaning traction control

2022-03-30T14:07:12Z

Active: formatting and unorphaning traction control

SpookySimon: words more and more better

2022-03-29T19:13:01Z

words more and more better

RealHumanBean: /* stuff you should get so you can figure out wth ur doing */

2020-06-09T01:48:27Z

stuff you should get so you can figure out wth ur doing

RealHumanBean: /* Tuning for Idle */

2020-06-09T01:47:16Z

Tuning for Idle

RealHumanBean: /* Open vs. Closed Loop Tuning */

2020-06-09T01:46:28Z

Open vs. Closed Loop Tuning

RealHumanBean: /* Alpha-n */

2020-06-09T01:43:27Z

Alpha-n

Toaster: Toaster moved page Engine control to Engine Control

2020-05-19T23:25:46Z

Toaster moved page Engine control to Engine Control

SpookySimon: /* Compensations */ tps

2020-05-19T14:40:19Z

Compensations: tps

SpookySimon: /* Tuning for Startup */ note

2020-05-19T14:39:19Z

Tuning for Startup: note

SpookySimon: /* Data used to run the engine */ word choice and minor formatting

2020-05-17T15:19:13Z

Data used to run the engine: word choice and minor formatting

@@ Line 5: / Line 5: @@
 cbr is carb stock
 ===Active===
-control spark - timing
+Parameters that can be independently controlled:
-control fuel - timing, duration (can't really change angle or placement so we put that under fuel system design, not here)
+* spark - timing
-control air - throttle
+* fuel - timing, duration (can't really change angle or placement so we can put that under fuel system design, not here)
-control temperature - radiator redirect valve, fan control
+* air - throttle
-control valve timing, valve lift (not electronically tunable, but still control, i'd be willing to put this under intake if that's a better place)
+* temperature - radiator redirect valve, fan control
 ==Tuning==
 Engine tuning is the idea of changing the inputs to the engine to achieve a desired goal. <span>Usually this goal is peak engine torque at every operating condition.</span>The engine will have to operate under a wide range of conditions. The two independent variables that are used to map the driving conditions are (1) Load and (2) RPM. Among the many knobs that can change how the engine performs are two factors that have outsized effects: how much gas to burn at a time and when in the engine cycle to burn it. In modern engines, the amount of fuel used at one time is most easily and finely controlled by changing how long the fuel injector is open. When the fuel is ignited can easily and finely be controlled by changing when the sparkplug is triggered.<span>The spark timing and fuel duration will each form a 3D surface when plotted against speed and load. (pic)</span>

@@ Line 11: / Line 11: @@
 control valve timing, valve lift (not electronically tunable, but still control, i'd be willing to put this under intake if that's a better place)
 ==Tuning==
-Engine tuning is the idea of changing the inputs to the engine to achieve a desired goal. The inputs available to tune depend on the engine control strategy. Usually this goal is peak engine torque at every operating condition. The two main inputs used to tune the engine are when charge ignition timing by changing the timing of the spark and quantity of fuel injected by changing the duration that the fuel injector is open. These two inputs are changed depending on the engine operating point: the torque requested (load) and the rotational speed of the engine. The spark timing and fuel duration will each form a 3D surface when plotted against speed and load. (pic)
+Engine tuning is the idea of changing the inputs to the engine to achieve a desired goal. <span>Usually this goal is peak engine torque at every operating condition.</span>The engine will have to operate under a wide range of conditions. The two independent variables that are used to map the driving conditions are (1) Load and (2) RPM. Among the many knobs that can change how the engine performs are two factors that have outsized effects: how much gas to burn at a time and when in the engine cycle to burn it. In modern engines, the amount of fuel used at one time is most easily and finely controlled by changing how long the fuel injector is open. When the fuel is ignited can easily and finely be controlled by changing when the sparkplug is triggered.<span>The spark timing and fuel duration will each form a 3D surface when plotted against speed and load. (pic)</span>
 ===Engine Control Strategies===
 ====Alpha-n====
@@ Line 19: / Line 24: @@
 =====Drawbacks=====
 This is throttle body dependent: change how your throttle is setup and your map is basically bunk unless you spend a lot of time getting it aligned with what you had.
 ====Speed-Density====
-There is also speed-density.
+Speed-density tuning uses the manifold absolute pressure (air density) to measure engine load.
 =====Advantages=====
 =====Drawbacks=====
@@ Line 28: / Line 32: @@
 =====Advantages=====
 =====Drawbacks=====
 ==Theory==
 ===Dithering===
@@ Line 35: / Line 38: @@
 ===Open vs. Closed Loop Tuning===
 open loop tuning is doing it yourself, run the engine and check the outputs. closed loop tuning is usually done to a specific lambda and is handled by the ECM. Closed loop control can be very powerful, but suffers in throttle transients, which is where FS cars spend a lot of time. Open loop control is an explicit formulation for fuel and spark based on throttle position, MAP, and pretty much everything besides Lambda. One dyno guy I talked to said that his drag cars run in open loop all the time. Correspondence with the ECU OEM I was working with noted that open loop is the first thing you should get down, and closed loop can do the last bit of engine fine control.
 ===Dynamometer===
 see [[:System Testing]]
 should have its own page also
 * mbt
 [diagram of spark timing on torque]
@@ Line 47: / Line 49: @@
 ===Fuel Tuning===
 * duration
 ** lbt
@@ Line 53: / Line 56: @@
 ===Tuning for Startup===
 give it a little gaz to get 'er going
 ===Tuning for Idle===
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 ==Compensations==
 * IAT - cooler air is denser and allows for more fuel burn, denser charge may need different spark advance
 * map (for alpha-n) - map allows for delays b/w throttle actuation and change in how much air is in intake system, esp with larger plenums, or extreme throttle changes (dump for accel, or complete lift-off)
@@ Line 94: / Line 97: @@
 ==cool data so you can do custom engine stuff==
 * cylinder pressure
 * knock sensor (cyl pressure can handle this if you have it)

@@ Line 90: / Line 90: @@
 ==stuff you should get so you can figure out wth ur doing==
 (safety stuff?)
-* oil pressure - low op means stop
+* oil pressure - low op means stop. The relationship between RPM and oil pressure is linear and if it falls off, you are in deep trouble or will be very soon.<br />
 * coolant temp - if its boiling, stop, regulation calls for water which boils at 212 (at normal altitudes @colorado)
 ==cool data so you can do custom engine stuff==
 * cylinder pressure

@@ Line 57: / Line 57: @@
 * Run lean, at least in the case of the 4cyls they do not seem to mind being 15+ [citation needed]<br />
-* Stock CBR idles at ~900RPM, rare that fsae cars run that low [citation needed]
+* Stock CBR idles at ~900RPM, rare that fsae cars run that low. In my experience anything below 2KRPM is a victory. [citation needed]
 * Idle air controllers are huge for accurate idle control. [citation needed]
 * Sharp pickup on throttle tip-in

@@ Line 34: / Line 34: @@
 Since the engine torque output is a non-linear function of many variables, and the resultant surface isn't analytically determinate, the torque surface is navigated by dithering. This involves running the engine on a dynamometer and, for each engine control variable, taking small steps in a direction and determining the effect the small step has on the torque. If the result is a decrease in torque, another direction is pursed. By chasing the direction of increasing torque for every operating condition, the engine control is optimized. this is just one big gradient ascent, but very badass.
 ===Open vs. Closed Loop Tuning===
-open loop tuning is doing it yourself, run the engine and check the outputs. closed loop tuning is usually done to a specific lambda and is handled by the ECM.
+open loop tuning is doing it yourself, run the engine and check the outputs. closed loop tuning is usually done to a specific lambda and is handled by the ECM. Closed loop control can be very powerful, but suffers in throttle transients, which is where FS cars spend a lot of time. Open loop control is an explicit formulation for fuel and spark based on throttle position, MAP, and pretty much everything besides Lambda. One dyno guy I talked to said that his drag cars run in open loop all the time. Correspondence with the ECU OEM I was working with noted that open loop is the first thing you should get down, and closed loop can do the last bit of engine fine control.
 ===Dynamometer===
 see [[:System Testing]]

← Older revision	Revision as of 23:25, 19 May 2020
(No difference)

← Older revision		Revision as of 14:39, 19 May 2020
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	===Tuning for Startup===		===Tuning for Startup===
		+	give it a little gaz to get 'er going
		+
	===Tuning for Idle===		===Tuning for Idle===

@@ Line 69: / Line 69: @@
 [link to daq and electronics]
 ==Data used to run the engine==
-(please someone come up with a better title for this section - simon)
+(please someone come up with a better title for this section - simon)<br />(needed if not running wasted spark)
 * cam sync sensor is needed to determine crank/valve angle - fire spark and fuel on every other rotation
 * determine place on fuel/spark map
 ** load (alpha, map, maf)
 ** rpm
 ==Compensations==
 * IAT - cooler air is denser and allows for more fuel burn, denser charge may need different spark advance