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Old 06-27-2003, 02:37 AM   #1
motorswapsleeper
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Default Need Help!!! You guys are my last hope.

Ok a couple of these questions have just been nagging me but, I am in the middle of a upgrade, the guys at vivid have no clue, and I need help post haste!
ok...
1. Can the sohc computer run a dohc motor?

2. Can my 2.5 dohc ecu run a turbo on it with out modifying it? I don't mind getting an air fuel controller. I know it is preferable to get the wrx ecu when turboing the n/a motors but I need it to run now...will it work?

3. Is there any one selling a wrx ecu or know where I can get one cheap?

Thank you much in advance.
-Tim
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Old 06-27-2003, 10:14 AM   #2
latinskllz
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Default Re: Need Help!!! You guys are my last hope.

Quote:
Originally posted by motorswapsleeper
Ok a couple of these questions have just been nagging me but, I am in the middle of a upgrade, the guys at vivid have no clue, and I need help post haste!
ok...
1. Can the sohc computer run a dohc motor?

2. Can my 2.5 dohc ecu run a turbo on it with out modifying it? I don't mind getting an air fuel controller. I know it is preferable to get the wrx ecu when turboing the n/a motors but I need it to run now...will it work?

3. Is there any one selling a wrx ecu or know where I can get one cheap?

Thank you much in advance.
-Tim
1) IIRC, the sohc ecu cannot run a dohc motor if the dohc motor has the dohc heads. I believe the dohc heads have two cam sensors instead of one so the sohc computer would not be able to pull the other one.

2) you can use your dohc ecu to run a turbo kit. It all really depends on what type of turbo, psi you are looking to be pushing. Remember, we have small 280cc (?) squirters so boost will be limited. If you get the WRX ecu, you should get the wrx wiring harness.

3) Do a search in the Private Classifieds, I saw one not too long ago.

Do you have any of the parts for your turbo project? It would be helpful to get an idea of what you are a planning to install so we can provide you clearer answers.

Hope this helps and if anyone needs to correct me, please do...

Kevin
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Old 06-27-2003, 11:14 AM   #3
Mancini
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Default

I'm running ~4psi on a DOHC engine with a stock ecu. The only electronics I'm using are an SAFC2 and an ITC. I had an rrfpr but took it out and am just using SAFC2 to control fuel under boost. The ITC has 1 degree of retard from 2400 up. So far so good...
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Old 06-27-2003, 06:20 PM   #4
motorswapsleeper
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Hey thank you, you guys are so much more knowledgeable! I have a couple more questions.
What is an itc do I need it?
What is limiting the boost to 4 psi?... the injectors or the ecu's ability to compute boost?
How much does the wrx harness cost?
Where can I get all the info on the wire colors and what they mean?
I need a complete wiring diagram, because the wires are a different on one side of the harness than the other.
Thank you, you guys have been awsome!
Just so you know, I am putting a 2 liter jdm turbo motor in my 1997 legacy that previously had a sohc 2.2 liter, will I need to get the 2.5 crnak pulley to match to timing?
Why didn't I just get the ecu? 1.It wouldn't be flexible enough for what I want to do, and 2.the guy wants way to much... 3.I don't mind doing harness work if I have to.
Thank all of you so much,I (and my engine)look forward to hearing from you again
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Old 06-27-2003, 07:42 PM   #5
Mancini
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Default

The ITC is from apexi and is an ignition timing controller, used to advance or retard timing. So you'd need it if you want to change the timing, which I would say yes if you're going boosted.

Boost is controlled by a Tial external wastegate and a .3Bar (~4psi) spring. That's the only thing physically controlling my boost. ECU has nothing to do with it other than interpreting the MAF sensor input or how much air is actually entering the engine. The SAFC then corrects to get to the proper A/F ratio for a boosted application.

If I were you I'd look into the WRX ECU since you'll be using a jdm 2.0 engine. I don't think the DOHC 2.5 ecu would work to well with a 2.0 engine.
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Old 06-27-2003, 10:17 PM   #6
Scoobie Steve
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Default

The 2.5l DOHC engine only has one cam sensor. the DOHC ecu is maf and the 2.5l SOHC ecu is map. The DOHC would be more flexible to boost because it will sense more airflow(NOT BOOST) and add some fuel(NOT ENOUGH TO BE SAFE). The ignition curve will be all wrong but it will work. The SOHC ecu doesnt like boost, it will throw a CEL, but that can be rigged too. The wrx ecu will be too much work, tumbler valves will be an issue along with other things. Its best to get the ecu that came with the engine or get an aftermarket one.

Last edited by Scoobie Steve; 06-29-2003 at 12:33 AM.
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Old 06-28-2003, 08:26 AM   #7
yebokmj
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Default Confusion

Okay the MY96-98 DOHC 2.5 engines will run no problem on a MY96-98 2.2 SOHC ecu and vise versa. It has been done before by me and a few others. I would think this would apply to other years as well. One great diss advantage to using the SOHC ecu is a loss of 1000 RPM being that the Rev limit is 6100 or 6200. The DOHC is like 6500-6600 and the WRX can range I believe from 7200 all the way up to 8000 or so depending on the WRX model.

Joshua
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