What does the MAP sensor do? - 600RR.net
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post #1 of 35 (permalink) Old 08-04-2010, 10:19 PM Thread Starter
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What does the MAP sensor do?

So I had an FI light come on and it turned out it was for a MAP sensor. I was able to fix it but really have no idea what a MAP sensor does.

Can someone explain what it does and what happens if it isn't working correctly?

thanks,

Bob

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post #2 of 35 (permalink) Old 08-04-2010, 10:24 PM
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It senses the manifold air pressure and sends it to the ECU to determine the conditions going into the engine. If the MAP sensors is bad, the ECU will think there is a problem and will put the bike in a limp mode, which basically lets the bike run but only enough to get it home or to a shop. Performance is severely retarded when a MAP sensors error is detected, since the ECU wont know if the problem is something that can or cannot damage the engine.
post #3 of 35 (permalink) Old 08-04-2010, 10:29 PM Thread Starter
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hmmm,

So first off, thanks Demented for helping me figure out how to get the DTC code so I could then look to fix the problem (different thread).

Regarding the map sensor error - I was still able to ride and have the bike run strong on the track. Seems that the idle is much improved now. It was sounding like a 60's muscle car and now has the familiar 600rr exhaust note.

Regardless, appreciate the explanation.

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post #4 of 35 (permalink) Old 08-08-2010, 02:48 PM
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Originally Posted by Demented View Post
It senses the manifold air pressure and sends it to the ECU to determine the conditions going into the engine.
The information the ECU gets from this sensor is one of the main variables used to determine the injector duty cycle. Without knowing the pressure in the manifold the ECU will probably decrease the A/F ratio and retard ignition timing (limp home mode) to protect the engine like Demented said.

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post #5 of 35 (permalink) Old 08-08-2010, 03:15 PM
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manifold absolute pressure**

Quote:
Originally Posted by Demented View Post
It senses the manifold air pressure and sends it to the ECU to determine the conditions going into the engine. If the MAP sensors is bad, the ECU will think there is a problem and will put the bike in a limp mode, which basically lets the bike run but only enough to get it home or to a shop. Performance is severely retarded when a MAP sensors error is detected, since the ECU wont know if the problem is something that can or cannot damage the engine.
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post #6 of 35 (permalink) Old 08-08-2010, 03:52 PM
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odds are the vacuum line on the bottom of the MAP sensor is loose, thats what my MAP code turned out to be
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post #7 of 35 (permalink) Old 08-08-2010, 04:15 PM
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The information the ECU gets from this sensor is one of the main variables used to determine the injector duty cycle. Without knowing the pressure in the manifold the ECU will probably decrease the A/F ratio and retard ignition timing (limp home mode) to protect the engine like Demented said.
Our ECU doesn't adjust injector duration or anything base don the MAP sensor. It's all a pre-determined fuel map that doesn't get adjusted in any way.

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manifold absolute pressure**
In case you didn't read closely, I never said what MAP stands for, so no need to correct anything.
post #8 of 35 (permalink) Old 08-08-2010, 10:05 PM
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Our ECU doesn't adjust injector duration or anything base don the MAP sensor. It's all a pre-determined fuel map that doesn't get adjusted in any way.
Unless our ECUs are much different than those used on cars, which I don't think they are, the input from the MAP sensor is used to select the fuel map.

Brian

Last edited by BWRX; 08-08-2010 at 10:08 PM.
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post #9 of 35 (permalink) Old 08-08-2010, 10:08 PM
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Unless our ECUs are much different than those used on cars, which I don't think they are, the input from the MAP sensor is used to select the fuel map.
They are much different. Injector duration, ignition timing, and secondary injector activation is all preset and never changes on the stock map.
post #10 of 35 (permalink) Old 08-08-2010, 10:14 PM
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So how does the ECU determine how much air is entering the engine?

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post #11 of 35 (permalink) Old 08-08-2010, 10:19 PM
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That's what the MAP is for. The ECU just doesn't adjust the a/f ratio any. There's no O2 sensors other than CA, EDM and JDM models for the ECU to detect if it adjusted the a/f ratio correctly.

The ECU just uses the sensors to detect the conditions going into the engine to determine if any engine damaging conditions are present. The only thing that adjusts the ignition is the knock sensor and the speed sensor.

Last edited by Demented; 08-08-2010 at 10:21 PM.
post #12 of 35 (permalink) Old 08-08-2010, 10:23 PM
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what is jdm and edm?
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post #13 of 35 (permalink) Old 08-08-2010, 10:24 PM
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what is jdm and edm?
Japanese Domestic Market and European Domestic Market.
post #14 of 35 (permalink) Old 08-08-2010, 10:25 PM
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That's what the MAP is for. The ECU just doesn't adjust the a/f ratio any.
Exactly, you want to maintain the A/F ratio which is why the ECU has to adjust the injector duty cycle based on the amount of air entering the engine, which is what the MAP sensor is for. Our cars do the same thing with a MAP or MAF sensor. It's there for more than just detecting a dangerous engine condition.

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post #15 of 35 (permalink) Old 08-08-2010, 10:27 PM
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A manifold absolute pressure sensor(MAP) is one of the sensors used in an internal combustion engine's electronic control system. Engines that use a MAP sensor are typically fuel injected. The manifold absolute pressure sensor provides instantaneous manifold pressure information to the engine's electronic control unit (ECU). The data is used to calculate air density and determine the engine's air mass flow rate, which in turn determines the required fuel metering for optimum combustion (see stoichiometry). A fuel-injected engine may alternately use a MAF (mass air flow) sensor to detect the intake airflow. A typical configuration employs one or the other, but seldom both.MAP sensor data can be converted to air mass data using the speed-density method. Engine speed (RPM) and air temperature are also necessary to complete the speed-density calculation.

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post #16 of 35 (permalink) Old 08-08-2010, 10:31 PM
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Quote:
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A manifold absolute pressure sensor(MAP) is one of the sensors used in an internal combustion engine's electronic control system. Engines that use a MAP sensor are typically fuel injected. The manifold absolute pressure sensor provides instantaneous manifold pressure information to the engine's electronic control unit (ECU). The data is used to calculate air density and determine the engine's air mass flow rate, which in turn determines the required fuel metering for optimum combustion (see stoichiometry). A fuel-injected engine may alternately use a MAF (mass air flow) sensor to detect the intake airflow. A typical configuration employs one or the other, but seldom both.MAP sensor data can be converted to air mass data using the speed-density method. Engine speed (RPM) and air temperature are also necessary to complete the speed-density calculation.
you should cite when you copy and paste something
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post #17 of 35 (permalink) Old 08-08-2010, 10:50 PM
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Exactly, you want to maintain the A/F ratio which is why the ECU has to adjust the injector duty cycle based on the amount of air entering the engine, which is what the MAP sensor is for. Our cars do the same thing with a MAP or MAF sensor. It's there for more than just detecting a dangerous engine condition.
Exactly what? I'm telling you that the ECU on the CBR600RR does not adjust the a/f ratio in any way, shape or form. The only time it will adjust the a/f ratio is when the engine is cold.

I'm a Honda trained tech with certifications in Honda's engine system for both cars and bikes.

The a/f ratio, as far as the ECU knows, stays a constant and is not adjusted. The MAP sensor is just there as a sensor, to make sure nothing bad is happening. If it detects a severe problem, it will put the engine in a limp mode to prevent damage.

That's why it's important to even remap our bikes with a PC3 or other fuel module for something as simple as changing the air filter.
post #18 of 35 (permalink) Old 08-08-2010, 11:06 PM
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Adjusting the injector duty cycle is required to maintain a constant A/F ratio, and I thought the ECU was advanced enough that it used the information from the MAP sensor in the injector duty cycle calculation. That's all I was saying. If you know for sure that it doesn't, then that really sucks because my 8 year old car has a more advanced ECU than the one in my high performance sport bike!

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post #19 of 35 (permalink) Old 08-08-2010, 11:07 PM
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you should cite when you copy and paste something
why is that? I was not taking credit for it, just adding more info for people.

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post #20 of 35 (permalink) Old 08-08-2010, 11:17 PM
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Adjusting the injector duty cycle is required to maintain a constant A/F ratio, and I thought the ECU was advanced enough that it used the information from the MAP sensor in the injector duty cycle calculation. That's all I was saying. If you know for sure that it doesn't, then that really sucks because my 8 year old car has a more advanced ECU than the one in my high performance sport bike!
I believe you're misreading what I am saying.

As far as the ECU knows, meaning it doesn't know, the a/f ratio is remaining unchanged. There are no O2 sensors on USD model bikes to monitor what the a/f ratio is for the ECU to even know. The ECU is set at one ratio, and that ratio is based off of predetermined measurements, and only uses the MAP and other sensors to know what is going into the engine. It does things a little backwards.

Honda did it for 2 reasons. One being it's cheaper, since it cuts out more programming and other sensors/wires. The other being that the stock ECU can't be hacked like what can be done to Yamaha, Suzuki, or Triumph ECU's to adjust injector duration. That then creates an actual market for the HRC ECU for race teams in racing leagues that do not allow things like the Power Commander or Bazazz units.
post #21 of 35 (permalink) Old 08-08-2010, 11:35 PM
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I got what you said. Ideally you would want a wideband o2 sensor to monitor the a/f ratio, but you don't need an o2 sensor to use the MAP sensor information for more than only problem detection.

I just can't believe Honda dumbed down the electronics for our bikes.

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post #22 of 35 (permalink) Old 08-08-2010, 11:40 PM
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They didn't really dumb it down, just built it to function as intended and nothing more. Honda's not the only one that does it on bikes though.
post #23 of 35 (permalink) Old 08-09-2010, 12:07 AM
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The bike is awesome as is, but they could have done better with the ECU. They certainly had the capability to make it more advanced than what it is.

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post #24 of 35 (permalink) Old 08-09-2010, 12:09 AM
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That's why they sell the HRC ECU.
post #25 of 35 (permalink) Old 08-09-2010, 12:32 AM
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And that's why our ECU is dumbed down ;)

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post #26 of 35 (permalink) Old 08-09-2010, 12:35 AM
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Except it's not dumbed down.
post #27 of 35 (permalink) Old 08-09-2010, 12:44 AM
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Hmmm, I will continue to lurk this thread for some e-drama anticipation

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post #28 of 35 (permalink) Old 08-09-2010, 01:03 AM
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Except it's not dumbed down.
It's dumbed down compared to ECU technology available on some cars almost 10 years ago. Surprising since Honda is such an automotive heavyweight.

If what I read about the HRC ECU is correct, it allows you to change the maps in the ECU. That's great, but that doesn't make it any more advanced than the stock ECU.

Brian

Last edited by BWRX; 08-09-2010 at 01:06 AM.
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post #29 of 35 (permalink) Old 08-09-2010, 01:58 AM
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Hmmm, I will continue to lurk this thread for some e-drama anticipation

bahahahaha
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post #30 of 35 (permalink) Old 08-09-2010, 02:05 AM
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It's dumbed down compared to ECU technology available on some cars almost 10 years ago. Surprising since Honda is such an automotive heavyweight.

If what I read about the HRC ECU is correct, it allows you to change the maps in the ECU. That's great, but that doesn't make it any more advanced than the stock ECU.
HRC ECU does far more then that.
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