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Old 06-28-2008, 06:47 PM   #1
armigerlives
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Member#: 180958
Join Date: May 2008
Chapter/Region: TXIC
Location: Texas
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2008 Homemade
Yellow

Cool 2.5 SOHC swap, doesn't weant to idle when warm

Heya, I performed a swap in the car I built from scratch about a month ago. The harness and ECU are out of an '93 impreza and the engine is from an 2000 outback. i am using the 2.5 coil/ignitor, i just bypassed the old separate ignitor that the 1.8 used. I am using the 1.8 throttle body mated to the 2.5 intake manifold via an adaptor I madeout of 20guage sheet steel. The engine runs real strong but when it is warm it doesn't want to idle when I stop. I tried adjusting teh set screw on the throttle body but I think the computer keeps overiding it. Any Ideas?

Here are some videos of the car, as well as some pics;
http://www.cardomain.com/ride/3088011
http://video.cardomain.com/armigerlives

Thanks!
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Old 06-30-2008, 02:16 PM   #2
jey
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You've probably already done this but first check for vaccuum leaks.
Next I'd check the Idle Control valve/actuator, make sure that's working as it should.
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Old 06-30-2008, 05:22 PM   #3
armigerlives
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ya That was the first thing I checked for, the IAC is definitely a possibility seeming as to how it is placed differently than the one on the 2.5 throttle body. I am going to swap the computer with one from an '93 2.2L and see how that effects things. The 2.2 has a 6500rpm rev limit as opposed to the 6k limit the 1.8 had. I think it might match the 2.5 a bit better.
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Old 06-30-2008, 05:28 PM   #4
ciper
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AWD 946 Rio Red Jpn built

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If its anything like the old IACs then it has a heat spring inside that closes off an extra air passage as the car gets warm. I'd try to open up the bypass screw on the TB to increase the warm IDLE and see if the cold idle can still be compensated for by the electronic portion of the IAC.
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Old 06-30-2008, 08:27 PM   #5
25rsti
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i have an iac sensor with about 10k miles if u need it, bought new from subaru for 350
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Old 07-02-2008, 07:29 AM   #6
armigerlives
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Thanks, adjusting the screw didn't effect anything except the idle in park and neutral. I have about 5 slightly used IAC's on other 1.8l engine and about 3 sitting on 2.5l engines. When I did the swap I didn't change the fuel pressure regulator from the 1.8 to he 2.5, I think I might do that.
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Old 07-02-2008, 04:27 PM   #7
ciper
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Leave the IAC attached as normal but remove the electronic portion on top and turn the shaft by hand and see if it is able to change the idle.
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Old 07-04-2008, 11:29 AM   #8
armigerlives
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The problem is that it will idle fine when it is in park or neutral. When it is in gear and I am stop at a light idling in gear it doesn't want to. Engine bucks, when I remove the wires from cylinders 1&3 it makes no difference (engine doesn't bog). Cylinders are getting spark, and fuel. As soon as you start to move it is all smooth, there is no missing. Any ideas? BTW I'm going to check the coil to see if that is the problem, just because I am getting spark doesn't mean it is "good" spark. Also the spark plugs are new. Was idling ok but got gradually worse. Thanks for any ideas on other possiblilities.
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Old 07-04-2008, 06:20 PM   #9
ciper
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So its an automatic? There is a small chance its the torque converter lockup malfunctioning. Once a month or so one of my Legacys does this and the car nearly dies before it finally unlocks.
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Old 07-05-2008, 12:06 AM   #10
armigerlives
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definitely not a converter locking up. I checked today and I think i'm not getting fuel to 1&3 while at idle
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Old 09-25-2008, 09:01 AM   #11
armigerlives
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Woot i finally figured it out. I had a bad ground from the Neg side of the battery to the frame. It ended up frying the computer. Since the injectors are high output they were the first things to have problems.... turns out I wasnt getting anything from the ecu to #3 injector. Re grounding the battery to the frame with a very good solid connection, then replacing the ECU (i happened to have another one lying around) fixed the issue. It now runs like a raped ape and idles smooth. Thanks for your imput
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