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Old 09-19-2010, 05:43 PM   #1
thefoos
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Default Swapping out a 16-bit ECU for a 32-bit

I'm starting to reach the limitations of the 16-bit ECU's that come on our 2.0L's (300g/s MAF and 24.75 psi commanded boost cap). I know there are work arounds, but I'm wondering if there is a better path.

I compared the schematics of the 02 WRX ECU and the 04 STi ECU, and for the most part, they are nearly identical. It appears the fuel controller might be a bit different, and you might have to swap around a few wires. I'm not sure if the absence of the DBW parts will matter. There are a couple other seemingly minor differences.

Anyhow, has anyone tried swapping in a 04 STi (or perhaps a 04 FXT) ECU into a 02-05 WRX? If not, I might have to be the guinea pig...
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Old 09-19-2010, 06:11 PM   #2
Hyper
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won't work, you would have to change pretty much everything
do your homework better

there are ways to overcome 300 g/s on 16 bit ecus
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Old 09-19-2010, 08:26 PM   #3
thefoos
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Quote:
Originally Posted by Hyper View Post
won't work, you would have to change pretty much everything
do your homework better

there are ways to overcome 300 g/s on 16 bit ecus
Yep, look at the wiring diagrams and the factory manuals show the ECU connectors being the same. Look at the I/O, and they are clearly different. Bad information in the schematics

I wasn't so concerned about the 300 g/s because that is easy to overcome. I mainly was concerned about the 24.75 psi cap. I realize there are ways around that too. I was hoping for a simple solution...

BTW, the "do your homework better" comment is unneeded. A simple no is good enough.

Last edited by thefoos; 09-19-2010 at 08:32 PM.
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Old 09-19-2010, 11:26 PM   #4
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for the boost cap, you can get a higher reading MAP sensor.
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Old 09-20-2010, 01:17 PM   #5
Hyper
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Originally Posted by lil'redwagon View Post
for the boost cap, you can get a higher reading MAP sensor.
doesn't matter
16bit ecu is unable to read higher that what's 255 which is maximum per bit

DBW ECUs are 4 pin last time I checked, DBC are 5 pin, so I don't see how they would be the same
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Old 09-20-2010, 02:22 PM   #6
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Buy an AVCR or something similar then.
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Old 09-20-2010, 08:20 PM   #7
thefoos
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^I can certainly run a MBC or aftermarket boost controller, I was just looking for a "stock" solution. Thinking outside the box a bit and exploring other options. Obviously, those old trusty standbys are always an option.
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Old 09-20-2010, 09:49 PM   #8
ThirtyTwo
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Quote:
Originally Posted by Hyper View Post
doesn't matter
16bit ecu is unable to read higher that what's 255 which is maximum per bit

DBW ECUs are 4 pin last time I checked, DBC are 5 pin, so I don't see how they would be the same
the 255 limit is only applicable when logging via the SSM protocol. You can implement a higher reading map sensor and log it with the "(direct)" parameter to read its full range. The ECU will also read the higher values internally, so any table with a boost reference will function when set higher than 24.75. Of course this also requires changing the MAP offsets and scalings, but thats not a big deal
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Old 09-24-2010, 12:32 PM   #9
fastblueufo
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Quote:
Originally Posted by ThirtyTwo View Post
the 255 limit is only applicable when logging via the SSM protocol. You can implement a higher reading map sensor and log it with the "(direct)" parameter to read its full range. The ECU will also read the higher values internally, so any table with a boost reference will function when set higher than 24.75. Of course this also requires changing the MAP offsets and scalings, but thats not a big deal
I don't think he is talking about logging, I think he is talking about the hard limit in the boost targets table. But why he would think that as a true limit for boost I don't know because it is not.
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