Axing the flapper style mas air meter
#26
Lives on the Forum
Originally posted by RexRyder
explain??? it could work if it was hooked up via throttle linkage (flapper on AFM). get a air/fuel mixture meter to see where ur leaning/richening then adjust it with the SAFC.
explain??? it could work if it was hooked up via throttle linkage (flapper on AFM). get a air/fuel mixture meter to see where ur leaning/richening then adjust it with the SAFC.
-Ted
#28
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Originally posted by dcfc3s
One thing I'm fixin' to experiment with is moving the AFM to the intercooler piping. It's much less of a restriction than before the turbo, and it's a really popular mod in Japan - there are countless FC's making 400-500 hp with the stock AFM in the IC piping - gotta be something to it .
One thing I'm fixin' to experiment with is moving the AFM to the intercooler piping. It's much less of a restriction than before the turbo, and it's a really popular mod in Japan - there are countless FC's making 400-500 hp with the stock AFM in the IC piping - gotta be something to it .
AFM relocated and return spring tension readjusted
HKS PFC F-CON
HKS FCD
HKS GCCII
HKS Twin Power Ignition
Of course, for the same price you could buy a standalone EMS, throw the AFM in the trash, and still have some cash left over, but then you couldn't put lots of HKS stickers on your car and look cool at the import meets.
#29
Super Newbie
Originally posted by Evil Aviator
but then you couldn't put lots of HKS stickers on your car and look cool at the import meets.
but then you couldn't put lots of HKS stickers on your car and look cool at the import meets.
#32
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Its been claimed a few times. Personally I don't see how it would work without other mods as the AFM is calibrated for operation at 1 atmosphere of pressure. It will measure lean as boost rises.
Henrik
87TII
Henrik
87TII
#33
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Originally posted by dcfc3s
One thing I'm fixin' to experiment with is moving the AFM to the intercooler piping. It's much less of a restriction than before the turbo...
One thing I'm fixin' to experiment with is moving the AFM to the intercooler piping. It's much less of a restriction than before the turbo...
I've yet to see anyone offer any proof that this makes any difference. That means before and after dyno runs with no other changes made. Any takers?
Last edited by NZConvertible; 01-02-03 at 10:31 PM.
#34
I'm a boost creep...
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Originally posted by Evil Aviator
No, you have it backwards. The stock FC systems ESTIMATE mass airflow based on expected turbo and intercooler output, while MAP-based systems (called Speed Density systems) CALCULATE the mass airflow if the sensors are properly positioned. Speed Density systems only require RPM and manifold pressure inputs.
No, you have it backwards. The stock FC systems ESTIMATE mass airflow based on expected turbo and intercooler output, while MAP-based systems (called Speed Density systems) CALCULATE the mass airflow if the sensors are properly positioned. Speed Density systems only require RPM and manifold pressure inputs.
ECU's with airflow meters are actually measuring the air they're ingesting, so thay can calculate the exact amount of fuel required to give the A/F ratio the ECU's fuel maps specify for the particular rpm/temp/etc conditions at the time. Flapper and sliding cone type AFM's like the FC's can't measure mass flow, only volume flow, so they have a built-in temp sensor so the ECU can calculate mass flow from volume flow and air temp. If you change the VE (intake and exhaust mods, porting, etc) with an AFM system the higher airflow is measured by the AFM and treated normally.
ECU's that use MAP (manifold absolute pressure) sensors as the load sensor (spped-density) have maps that basically say at X manifold pressure and Y rpm there is supposed to be Z airflow, and then calculate the fuel required from there. But they are only estimating the airflow based on the values found by the programmers experimentation on the stock engine and bolt-ons. If you change the VE, the relationship between manifold pressure and flow changes and this introduces errors in the ECU's airflow estimates. This is why speed-density systems (including aftermarket ECU's) are less tolerant of mods that AFM systems.
#35
Post count is over rated
My friend did this mod he's running the factory computer with a custom fuel set up .this is the part that gets me , THEY CUT OFF THE BOOST SENSOR.THIS IS HOW HE RUNS 12.3
550 CC PRIMARES
1600 SECONDARIES
SX FPR
STOCK COMPUTER
FRONT MOUNT WITH THE AFM MOUNTED RIGHT AFTER THE TURBO
AND TWO SS BOV'S MOUNTED RIGHT AFTER THE THROTTLE BODY , SO THE AFM DOESN'T BLOW UP AFTER HE **** OFF THE THROTTLE.
oops sorry forcaps lock. he also is runing a full to4.
i will try to take sum pix if he let's me.
550 CC PRIMARES
1600 SECONDARIES
SX FPR
STOCK COMPUTER
FRONT MOUNT WITH THE AFM MOUNTED RIGHT AFTER THE TURBO
AND TWO SS BOV'S MOUNTED RIGHT AFTER THE THROTTLE BODY , SO THE AFM DOESN'T BLOW UP AFTER HE **** OFF THE THROTTLE.
oops sorry forcaps lock. he also is runing a full to4.
i will try to take sum pix if he let's me.
#38
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So would the afm survive if it was placed right before the TB after the BOV?
Im sure it would have better response with that position then before the turbo. And i dont think you need all those HKS piggybacks to mount the afm in that position.
Im sure it would have better response with that position then before the turbo. And i dont think you need all those HKS piggybacks to mount the afm in that position.
#39
My Custom Title > Your's
From what Ive been told I have gathered the understanding that if you place the AFM after the turbo and before the TB you run into the problem of innacuracies in that the air there is essentially backed up when under pressure and doesnt really move past the flapper b/c a constant supply is going in as coming out or something to that degree. Also it sounds rather cheap and worthless
#40
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How does it sound cheap and worthless? The engine changes its sound because of this?
And no, the afm would deffinetly open, the column of pressurized air is moving into the engine except when the throttle closes and the BOV vents. Thats when response is improved and no more hesitatrion after a shift.
And no, the afm would deffinetly open, the column of pressurized air is moving into the engine except when the throttle closes and the BOV vents. Thats when response is improved and no more hesitatrion after a shift.
#41
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Originally posted by NZConvertible
No, you've got it backwards.
No, you've got it backwards.
#42
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Originally posted by Evil Aviator
LOL, you are missing the point. The stock AFM measures the airflow prior to the turbocharger heating the air, the intercooler cooling it, and the rest of the intake taking its pressure drop toll. Therefore, the ECU must estimate the temperature and pressure of the air in the manifold. In English, the stock AFM has absolutely no idea what is really happening in the intake manifold. An aftermarket speed-density EMS can calculate this better with sensors which are actually mounted in or near the manifold. This is also why mounting the stock AFM downstream of the IC would allow for more accurate operational information, assuming that some type of piggy-back ECU could take advantage of this information.
LOL, you are missing the point. The stock AFM measures the airflow prior to the turbocharger heating the air, the intercooler cooling it, and the rest of the intake taking its pressure drop toll. Therefore, the ECU must estimate the temperature and pressure of the air in the manifold. In English, the stock AFM has absolutely no idea what is really happening in the intake manifold. An aftermarket speed-density EMS can calculate this better with sensors which are actually mounted in or near the manifold. This is also why mounting the stock AFM downstream of the IC would allow for more accurate operational information, assuming that some type of piggy-back ECU could take advantage of this information.
Henrik
87TII
#47
Super Newbie
Originally posted by Evil Aviator
It must be there so that the ECU can compensate for vacuum leaks.
It must be there so that the ECU can compensate for vacuum leaks.