gathermewool
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Originally Posted By: GMBoy
Originally Posted By: gathermewool
Originally Posted By: 05Blazer
From Trusted GM employee at the assembley plan:
You don't need a tune with a cold air intake. The internet forums are wrong. The air still passes thru the MAF sensor and that tells the engine how much air is coming in. The baffles are for noise cancellation purposes.
Sorry, but your buddy is 100% wrong on this front. The Mass Airflow sensor is scaled and its values entered into your ECU's memory (it's essentially a lookup table.) If you change the diameter or geometry of your intake, then a larger amount of air could be sucked past the MAF sensor without the MAF sensor actually accounting for it all, since less air would flow past the sensor for the same overall volume.
In this case, the FEEDBACK would be via the ECU reading the discrepancy in the O2 sensor reading from what it what it looked up in that cells respective fueling table and adding or subtracting fuel as necessary. Even if your fuel trims are stored in memory doesn't mean that there won't be times when your ECU can't account for the discrepancy in what tube the MAF sensor was scaled to work with and what you installed. You must either rescale your MAF to work with the new intake or rely upon the ECU to adjust your fuel trim.
Again, the MAF sensor will not account for a change in your intake. The ECU will receive a lean reading from the O2 sensor and adjust your fuel trim after the fact. I'm sure every vehicle is different, but this is how my Subie operates, and this is how I believe all MAF-based fueling systems operate.
Umm..no I am not. You are wrong and try telling that to the Powertrain engineer sitting right behind me. The comment about air getting by the MAF unregistered is very amusing to me. ALL air will go thru it and be registered. A cold air kit does not provide so much more air that the ECM cannot compensate. Now, adding exhaust then you can benefit from a tune. But stock - no way - our system can handle it.
Originally Posted By: GMBoy
Originally Posted By: gathermewool
Originally Posted By: 05Blazer
From Trusted GM employee at the assembley plan:
You don't need a tune with a cold air intake. The internet forums are wrong. The air still passes thru the MAF sensor and that tells the engine how much air is coming in. The baffles are for noise cancellation purposes.
Sorry, but your buddy is 100% wrong on this front. The Mass Airflow sensor is scaled and its values entered into your ECU's memory (it's essentially a lookup table.) If you change the diameter or geometry of your intake, then a larger amount of air could be sucked past the MAF sensor without the MAF sensor actually accounting for it all, since less air would flow past the sensor for the same overall volume.
In this case, the FEEDBACK would be via the ECU reading the discrepancy in the O2 sensor reading from what it what it looked up in that cells respective fueling table and adding or subtracting fuel as necessary. Even if your fuel trims are stored in memory doesn't mean that there won't be times when your ECU can't account for the discrepancy in what tube the MAF sensor was scaled to work with and what you installed. You must either rescale your MAF to work with the new intake or rely upon the ECU to adjust your fuel trim.
Again, the MAF sensor will not account for a change in your intake. The ECU will receive a lean reading from the O2 sensor and adjust your fuel trim after the fact. I'm sure every vehicle is different, but this is how my Subie operates, and this is how I believe all MAF-based fueling systems operate.
Umm..no I am not. You are wrong and try telling that to the Powertrain engineer sitting right behind me. The comment about air getting by the MAF unregistered is very amusing to me. ALL air will go thru it and be registered. A cold air kit does not provide so much more air that the ECM cannot compensate. Now, adding exhaust then you can benefit from a tune. But stock - no way - our system can handle it.
Is he a member here on BITOG, too? Telling some one they're wrong, but not providing anything to further the discussion or prove your point doesn't really help.
Subaru ECM's are just as capable of keeping up with some aftermarket intakes - that's not the point. The point is that our MAF, if placed in a differently-sized section of intake tract from OEM, will no longer be scaled correctly. So, even if the ECM can compensate (which it does via it's FEEDBACK loop, the O2 sensor reading,) that doesn't mean that slapping an aftermarket intake on is always the right thing to do. SteveSRT8 and 440Magnum are right, in that it's definitely application specific. The conversation has expanded beyond that, which I hope is ok, and not too far off topic. I really think it's a good conversation to have, and simply calling people wrong doesn't help. Instead, please explain your point.
In Subaru tuning, the fueling tables won't need to be touched for a change in the intake, only (that's not to say a tuner can't change both timing AND fueling to provide what's known as a "stage 1+" tune, denoting an all-stock vehicle, plus an intake.) For the addition of an intake, the ECM may be able to compensate, but having the MAF scaled, which involves aligning the scaling table, which basically tells the ECM how much air for the range of voltage the MAF inputs.
I'm going to say again that there are turbo Subie owners who slap intakes on and will probably never experience an issue, just as a GM owner might not, but our turbo application may be a little more sensitive to changes in AFR.
Originally Posted By: gathermewool
Originally Posted By: 05Blazer
From Trusted GM employee at the assembley plan:
You don't need a tune with a cold air intake. The internet forums are wrong. The air still passes thru the MAF sensor and that tells the engine how much air is coming in. The baffles are for noise cancellation purposes.
Sorry, but your buddy is 100% wrong on this front. The Mass Airflow sensor is scaled and its values entered into your ECU's memory (it's essentially a lookup table.) If you change the diameter or geometry of your intake, then a larger amount of air could be sucked past the MAF sensor without the MAF sensor actually accounting for it all, since less air would flow past the sensor for the same overall volume.
In this case, the FEEDBACK would be via the ECU reading the discrepancy in the O2 sensor reading from what it what it looked up in that cells respective fueling table and adding or subtracting fuel as necessary. Even if your fuel trims are stored in memory doesn't mean that there won't be times when your ECU can't account for the discrepancy in what tube the MAF sensor was scaled to work with and what you installed. You must either rescale your MAF to work with the new intake or rely upon the ECU to adjust your fuel trim.
Again, the MAF sensor will not account for a change in your intake. The ECU will receive a lean reading from the O2 sensor and adjust your fuel trim after the fact. I'm sure every vehicle is different, but this is how my Subie operates, and this is how I believe all MAF-based fueling systems operate.
Umm..no I am not. You are wrong and try telling that to the Powertrain engineer sitting right behind me. The comment about air getting by the MAF unregistered is very amusing to me. ALL air will go thru it and be registered. A cold air kit does not provide so much more air that the ECM cannot compensate. Now, adding exhaust then you can benefit from a tune. But stock - no way - our system can handle it.
Originally Posted By: GMBoy
Originally Posted By: gathermewool
Originally Posted By: 05Blazer
From Trusted GM employee at the assembley plan:
You don't need a tune with a cold air intake. The internet forums are wrong. The air still passes thru the MAF sensor and that tells the engine how much air is coming in. The baffles are for noise cancellation purposes.
Sorry, but your buddy is 100% wrong on this front. The Mass Airflow sensor is scaled and its values entered into your ECU's memory (it's essentially a lookup table.) If you change the diameter or geometry of your intake, then a larger amount of air could be sucked past the MAF sensor without the MAF sensor actually accounting for it all, since less air would flow past the sensor for the same overall volume.
In this case, the FEEDBACK would be via the ECU reading the discrepancy in the O2 sensor reading from what it what it looked up in that cells respective fueling table and adding or subtracting fuel as necessary. Even if your fuel trims are stored in memory doesn't mean that there won't be times when your ECU can't account for the discrepancy in what tube the MAF sensor was scaled to work with and what you installed. You must either rescale your MAF to work with the new intake or rely upon the ECU to adjust your fuel trim.
Again, the MAF sensor will not account for a change in your intake. The ECU will receive a lean reading from the O2 sensor and adjust your fuel trim after the fact. I'm sure every vehicle is different, but this is how my Subie operates, and this is how I believe all MAF-based fueling systems operate.
Umm..no I am not. You are wrong and try telling that to the Powertrain engineer sitting right behind me. The comment about air getting by the MAF unregistered is very amusing to me. ALL air will go thru it and be registered. A cold air kit does not provide so much more air that the ECM cannot compensate. Now, adding exhaust then you can benefit from a tune. But stock - no way - our system can handle it.
Is he a member here on BITOG, too? Telling some one they're wrong, but not providing anything to further the discussion or prove your point doesn't really help.
Subaru ECM's are just as capable of keeping up with some aftermarket intakes - that's not the point. The point is that our MAF, if placed in a differently-sized section of intake tract from OEM, will no longer be scaled correctly. So, even if the ECM can compensate (which it does via it's FEEDBACK loop, the O2 sensor reading,) that doesn't mean that slapping an aftermarket intake on is always the right thing to do. SteveSRT8 and 440Magnum are right, in that it's definitely application specific. The conversation has expanded beyond that, which I hope is ok, and not too far off topic. I really think it's a good conversation to have, and simply calling people wrong doesn't help. Instead, please explain your point.
In Subaru tuning, the fueling tables won't need to be touched for a change in the intake, only (that's not to say a tuner can't change both timing AND fueling to provide what's known as a "stage 1+" tune, denoting an all-stock vehicle, plus an intake.) For the addition of an intake, the ECM may be able to compensate, but having the MAF scaled, which involves aligning the scaling table, which basically tells the ECM how much air for the range of voltage the MAF inputs.
I'm going to say again that there are turbo Subie owners who slap intakes on and will probably never experience an issue, just as a GM owner might not, but our turbo application may be a little more sensitive to changes in AFR.
