Can a 89+ AFM be used in a pre 89???
08-16-02, 05:46 PM
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Can a 89+ AFM be used in a pre 89???
Can this be done??? Is there any writeup?? I wouldn't mind putting one in due to its size, but i see that the plug is different. If it can done is it worth it???
Thx
LoS
Thx
LoS
08-16-02, 06:46 PM
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Some people have claimed to have doen it, there are a couple of sites that show the wiring changes. HOWEVER the AFM's operate differently. RETED or NZconvertible can explain this much better than I.
08-16-02, 08:14 PM
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From an earlier post from NZCONVERTIBLE:
5/27/02:
Two probs:
1) The S5 AFM may have less internal resistance than the S4 one, but it's inlet is actually a bit smaller (60mm dia. vs 60x50mm), so I really doubt there'd be much difference in flow. As for power, you'd need a really good dyno to pick it.
2) You can't just "map the S5 pins to the S4 pins". The flow characteristics of a sliding cone AFM are totally different to a trapdoor type. You'd be sending completely wrong signals to the ECU.
Despite the number of times this comes up, and the number of times someone just says "it can be done", AFAIK nobdy's put their hand up and said "I did it, here's how I did it and here's the results". After 14 years, if it hasn't been done, it probably can't; and if it has, it ain't worth the trouble.
quote:
--------------------------------------------------------------------------------
Originally posted by XimbueX
I'm curious why you say mapping the pins together sends the wrong signal to the ECU...
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It's the relationship between airflow and output voltage that's different. This is because the flapper type AFM has an output that's close to logarithmic. It only takes a little airflow to move through the first part of the flap's sweep, but because less and less of the flap is in the airstream as it swings open, a lot more airflow is required to move it through the last part of its sweep. The sliding cone type AFM has a much more linear movement of the cone as airflow increases, and hence its output is also close to linear.
Because of this, I'd be really surprised if the open-loop mixtures in your friends car weren't altered by the change of AFM. If they were right before, they won't be now. The difference may not be huge (not enough to see on a gauge on the stock O2 sensor), but do you really want to be making changes that have an unknown effect on mixtures?
Airflow is the other issue. Was the car dyno'd before and after? I doubt you'd see any difference because even if the S5 AFM can outflow the S4 one by 10% (on a flowbench, which I doubt), the difference it'll make to the whole engine's flow would be tiny.
I've never said it can't be done, just that there's no good reason to do it, not one backed up with any hard data anyway. Anyone care to prove me wrong? If I am, I'll buy one and swap them the next day!
5/27/02:
Two probs:
1) The S5 AFM may have less internal resistance than the S4 one, but it's inlet is actually a bit smaller (60mm dia. vs 60x50mm), so I really doubt there'd be much difference in flow. As for power, you'd need a really good dyno to pick it.
2) You can't just "map the S5 pins to the S4 pins". The flow characteristics of a sliding cone AFM are totally different to a trapdoor type. You'd be sending completely wrong signals to the ECU.
Despite the number of times this comes up, and the number of times someone just says "it can be done", AFAIK nobdy's put their hand up and said "I did it, here's how I did it and here's the results". After 14 years, if it hasn't been done, it probably can't; and if it has, it ain't worth the trouble.
quote:
--------------------------------------------------------------------------------
Originally posted by XimbueX
I'm curious why you say mapping the pins together sends the wrong signal to the ECU...
--------------------------------------------------------------------------------
It's the relationship between airflow and output voltage that's different. This is because the flapper type AFM has an output that's close to logarithmic. It only takes a little airflow to move through the first part of the flap's sweep, but because less and less of the flap is in the airstream as it swings open, a lot more airflow is required to move it through the last part of its sweep. The sliding cone type AFM has a much more linear movement of the cone as airflow increases, and hence its output is also close to linear.
Because of this, I'd be really surprised if the open-loop mixtures in your friends car weren't altered by the change of AFM. If they were right before, they won't be now. The difference may not be huge (not enough to see on a gauge on the stock O2 sensor), but do you really want to be making changes that have an unknown effect on mixtures?
Airflow is the other issue. Was the car dyno'd before and after? I doubt you'd see any difference because even if the S5 AFM can outflow the S4 one by 10% (on a flowbench, which I doubt), the difference it'll make to the whole engine's flow would be tiny.
I've never said it can't be done, just that there's no good reason to do it, not one backed up with any hard data anyway. Anyone care to prove me wrong? If I am, I'll buy one and swap them the next day!
08-16-02, 08:21 PM
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I'm still waiting to see a dyno that says the kouki FC AFM creates more HP or has better flow characteristics vs the zenkei...
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