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Old 01-05-2011, 06:11 PM   #1
Scooby Newbie
Member#: 251356
Join Date: Jul 2010
Default 96 Legacy 2.2 into 97 Impreza front cylinders not firing

I am near the end of this swap, but have encountered some problems. I'll give the whole story here, but if you don't care and just want to fix my problems, please scroll down to the "PROBLEM" section

This is my first subaru: an abused 5-speed 1997 Impreza (outback, I think) N/A 2.2L. Before this, I've messed with trucks and then a couple nissans. I really wanted AWD though, and have always liked subarus. So when I had the chance to get this impreza for 150$, I took it. Now, it didn't run then, that might be important later.

My friend had tried to do a water pump and timing belt, but didn't put the belt on right, and ran it. I messed with it for a while but it wouldn't start despite the presence of spark and gas. I eventually found it had no compression, but I only turned it over a few times by hand with a socket driver on the crank. I also got the hose of my comp. tester stuck in that cyllinder, where it still remains. I had thought it was non-interference, but did some research and discovered single exhaust port meant interference (starting half way through 96, right?), and I concluded that the valves were all bent.

I found a 96 legacy outback with all sorts of body damage and a running motor, so I bought it for 400$ and decided I'd do a swap. Now that motor is in the impreza, and something's not right.


It runs, but doesn't like to start and will only run on the rear two cylinders (3 and 4, I think). It will only start at WOT after a lot of pedal pumping.

It throws P0106 and P0507, but I think that's just because the vacuum from the engine running on two cylinders is lower than it should be, so the MAP should be reading low. And to keep the engine running, the idle has to be at like 1000, it will stall if I let it drop down. I see 106 a lot more than 507 and I followed someone's instructions for cleaning the IACV.

I tried swapping the MAP sensor and vacuum solenoids (both in the MAP line and the EVAP system) with the components from the donor car. I checked with my pics of the pre-install state and I am pretty sure of the vacuum routing and all these components now. I looked for leaks with WD-40 and found none.

I cleaned the MAF too. It was pretty clean already.

I have a spark plug test light, three coil packs, and three sets of wires, I don't think it's spark-related. The light was really weak, but, at the time, I figured that's just how it is.

I tried pinching the fuel return line to see if my fuel pressure regulator was bad, it didn't increase RPM.

I unplugged fuel injectors to see which cylinders were firing, and found that the front two could be unplugged without affecting the engine. So I thought OK, dirty injectors, cool. But, I did some research first and found some folks skeptical of the signal to the injectors, so I checked that with a computer (see http://imgur.com/a/EIRDw/subaruarduino, I am a nerd) So with signal going to the faulty injectors, I hoped they were totally jammed. I installed the rails and injectors from the original motor.

I could probably torch the head of the old motor and retrieve my compression tester, but that might tell me something I don't want to hear. Could it be head gasket problems on just the front most cylinder on each head? I'm not leaking coolant either. But maybe those front valves are trashed? Did I mention this motor ran in the legacy?

I am hoping it is the ECU (ECM?) and was hoping for a second opinion, I took the ECU out of the legacy already. I think the impreza's is up under the dash and seems different. Will they be compatible? I will look into this myself tomorrow and keep you all updated. If anyone has any ideas, I'd love to hear them.

If it was the ECU and I didn't do the comp. test right? Could that other motor still be good? Is it indeed an interference?

My first thread!
Did they mod the dictionary to troll skeptics?
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Old 01-05-2011, 06:49 PM   #2
Scooby Newbie
Member#: 251356
Join Date: Jul 2010

Oh, and new PCV valve
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Old 01-06-2011, 09:48 PM   #3
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Member#: 123362
Join Date: Aug 2006
Chapter/Region: MWSOC
Location: Dorothy's House
'93 Crapcan EJ25D


Curious, were the cam and crank sensors the same on the pulled engine vs. the swapped engine? What did you swap from the old engine to the new engine, if anything?
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Old 01-06-2011, 10:50 PM   #4
Scooby Newbie
Member#: 251356
Join Date: Jul 2010

I never touched those sensors besides plugging them in, they matched perfectly and I figured it couldn't fire the back two correctly without them, also, I didn't get a code for them.

Well, she's running much better now.
I removed the poorly installed security system and cleaned up the wiring under the steering column, didn't find any shorts or bad grounds. Then I opened up the ECU compartment and found that the case has quite a bit of rust on it. So then, using http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/coilpacktest.jpg I tested the coil to be sure it was good, it was.

Then took a look at the signal to the ignitor. One of the pins' voltage varied with cranking, but the other wasn't doing anything. So then I grabbed the pinout of the ECU, removed the plug and checked the connection to both those pins on the ignitor (40 and 41 on the ECU plug) It was then I discovered on the ECU pinout that these were grouped as cylinders 1 & 2 and cylinders 3 & 4, which matched up with the issue I was having!! I also noticed that the ecu had just a little bit of rust near the plug area, so I put the ECU from the legacy in, which I previously checked for compatibility.

During the coil testing, I learned about Hitachi vs. Diamond ignition systems. Not sure if it makes a difference, but I went with the hitachi system that the legacy ECU used to drive, and grabbed the ignitor off the legacy. I made a new mount for the ignitor, because I didn't think the other was grounding very well.

Fired it up and it was idling on it's own and running relatively smooth.... but not totally smooth. I am hoping it just needs to learn some. No codes yet. I took it for a short drive and saw that it had torque again, I am pretty happy.

Here's the final setup (pictures tomorrow, maybe):
Parts from the 96 Legacy:
Engine, 5mt, ECU, ignitor, MAP sensor

From the 97 Impreza:
Fuel rails, injectors, harness, whole rest of car

There is some custom stuff too, but nothing good.
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