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Nitrous
- Joined
- Dec 31, 2006
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Here's what I've learned so far... feel free to educate me if I've left anything out.
Basic fuel delivery to the engine is determined by the MAP sensor and RPM signal. The Throttle Position sensor and Baro Sensor support these two. The MAP sensor takes the place of the power valve in a carburetor and vacuum advance diaphragm on a distributor. When engine load is high, the fuel injectors remain on longer. The sensor ignores the signal from the O2 sensor under high load. You can cause the mixture to go very rich by disconnecting the vacuum supply to the MAP sensor... the engine will run extremely rich. The ECU also retards the timing under high load.
The MAP sensor controls the Acceleration Enrichment Tables in the ECU. Acceleration Enrichment is additional fuel used to improve throttle response, much like an accelerator pump on a carburetor. This fuel is applied in response to a positive throttle position rate of change or a positive manifold pressure rate of change. The resulting increase in manifold pressure can cause some of the fuel in the intake runners to undergo a phase change from vapor to liquid. Some of the liquid fuel can coat the walls of the intake runners instead of flowing into the cylinder. If additional fuel is not supplied to offset this effect, the engine will experience a lean condition.
If you disconnect the MAP sensor vacuum line, problems can include detonation, power loss, stalling, rough idle, and poor fuel economy. With a disconnected MAP sensor vacuum line, the ECU "sees" high load. It compensates by lengthening the fuel injector pulse width and retards the ignition. So if you then re-tune the engine with a disconnected MAP sensor, you no longer have "load" info going to your ECU when you need it. This will result in a loss of performance, and in the worst cases... burned pistons. The only way to compensate for this is to tune an engine with a disconnected MAP sensor way too rich... not for performance. Most supercharged R3 riders don't notice the lack of performance because they are comparing it to their naturally aspirated experience... and don't have digital A/F indicators.
A supercharged R3 can be re-tuned to run smoothly with a 2 bar MAP sensor. Is it perfect? No... ideally when installing a 2 bar MAP sensor on a 14psi boosted engine, you should tell the ECU the new MAP sensor parameters. Like this...
IMO, this is the option that is needed in the TuneBoy program... not a MAP sensor delete button.
Basic fuel delivery to the engine is determined by the MAP sensor and RPM signal. The Throttle Position sensor and Baro Sensor support these two. The MAP sensor takes the place of the power valve in a carburetor and vacuum advance diaphragm on a distributor. When engine load is high, the fuel injectors remain on longer. The sensor ignores the signal from the O2 sensor under high load. You can cause the mixture to go very rich by disconnecting the vacuum supply to the MAP sensor... the engine will run extremely rich. The ECU also retards the timing under high load.
The MAP sensor controls the Acceleration Enrichment Tables in the ECU. Acceleration Enrichment is additional fuel used to improve throttle response, much like an accelerator pump on a carburetor. This fuel is applied in response to a positive throttle position rate of change or a positive manifold pressure rate of change. The resulting increase in manifold pressure can cause some of the fuel in the intake runners to undergo a phase change from vapor to liquid. Some of the liquid fuel can coat the walls of the intake runners instead of flowing into the cylinder. If additional fuel is not supplied to offset this effect, the engine will experience a lean condition.
If you disconnect the MAP sensor vacuum line, problems can include detonation, power loss, stalling, rough idle, and poor fuel economy. With a disconnected MAP sensor vacuum line, the ECU "sees" high load. It compensates by lengthening the fuel injector pulse width and retards the ignition. So if you then re-tune the engine with a disconnected MAP sensor, you no longer have "load" info going to your ECU when you need it. This will result in a loss of performance, and in the worst cases... burned pistons. The only way to compensate for this is to tune an engine with a disconnected MAP sensor way too rich... not for performance. Most supercharged R3 riders don't notice the lack of performance because they are comparing it to their naturally aspirated experience... and don't have digital A/F indicators.
A supercharged R3 can be re-tuned to run smoothly with a 2 bar MAP sensor. Is it perfect? No... ideally when installing a 2 bar MAP sensor on a 14psi boosted engine, you should tell the ECU the new MAP sensor parameters. Like this...
IMO, this is the option that is needed in the TuneBoy program... not a MAP sensor delete button.