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sprinkles08, ASE Certified Technician
Category: Subaru
Satisfied Customers: 22802
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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2010 subaru impreza wagon 2.5i premium Engine is SOHC EJ25

Customer Question

2010 subaru impreza wagon 2.5i premiumEngine is SOHC EJ25Just had engine completely rebuilt at Subaru engine shop.
I installed the engine in my car a few days ago, and it will not start. (I have a 2008 impreza with the same exact engine. I bought the 2010 with a spun bearing so I took the engine out to be rebuilt, and put my 2008 engine in the 2010 until Saturday when I took the 2008 engine out, and installed the rebuilt engine.)Engine turns over normally, just will not startThings I have done to find the problem thus far:charged and tested battery
triple checked all electrical connectors, and all grounds
checked compression in cylinders
verified fuel pump is operating, plugs smell like fuel as well
tested ignition coil with multi meter and switched coil into my 2008 - starts right up
switched cam position sensor into 2008 - starts right up
switched crank position sensor into 2008 - starts right up
removed timing cover to verify proper timing - (compression test told me timing was ok)
Timing marks appear to be properly aligned.....but...
is it possible that the crank gear was set 180 degrees out? marks would still line up, would be no interference but crank sensor would fire at bdc instead of tdc?
Submitted: 11 months ago.
Category: Subaru
Expert:  Mike V. replied 11 months ago.

Hello and thank you for your question!
My name is ***** ***** I will be assisting you with your question today.

Expert:  Mike V. replied 11 months ago.

You can't align the crank on this 180 off and have the timing belt line up.

Can you tell me if the woodruff key on the crank is in the 6 o'clock position when all the timing marks are lined up?

Customer: replied 11 months ago.
but isn't it possible to spin the crank 360 degrees which would put the key at 6 o-clock but it would be on a compression stroke instead of an exhaust stroke?
Customer: replied 11 months ago.
or vice versa?
Customer: replied 11 months ago.
When I said 180 out, I meant the timing, since the crank gear makes two revolutions for every one revolution of the cam gears
Expert:  Mike V. replied 11 months ago.

That's not how these work. When you have the key at 6, then the timing mark is at 12. All this does is pulls all the pistons in to the center of the engine so the valves can't make contact with the piston.

Expert:  Mike V. replied 11 months ago.

First thing to check on this is that the crank sprocket is the same on both engines. Sometimes with the year change they change the sprockets for the cam or crank sensors. When this happens the computer isn't seeing the right signal and you won't get spark.

Customer: replied 11 months ago.
I understand that.... Lets say that I went right now and pulled the belt off, and spun the crank one revolution, and re-installed the belt - Wouldn't that change the direction of the #1 piston? These engines are literally identical - the sensors were in the 2010 that won't start so I was eliminating causes by trying the sensors that were in the 2010, non-starting engine, into the 2008 to see if they were bad. The 2008 started right up with: the coil, the crank position sensor, and the cam position sensor from the 2010 non-starting engine.
Customer: replied 11 months ago.
I also tried them one at a time to make sure of what was bad, if the 2008 wouldn't start
Customer: replied 11 months ago.
I started with the coil as I had put a clip on spark tester on to the spark plug wire last night, and I didn't see any spark from the tester. I then tested the coil with a multimeter for resistance, and cross checked my readings with the coil from the 2008 that is working fine
Customer: replied 11 months ago.
Do you know what I was asking about the crank gear possibly being off one revolution?
Expert:  Mike V. replied 11 months ago.

As long as that line on the crank is pointing at 12 o'clock when you rotate the crank one complete turn, you aren't changing anything.

As for the sensors, it's going to read the cam and crank sprockets, thats where the difference would be, not in the sensor. The number of teeth on the sprocket. So the 08 will fire without issue because the computer is seeing the signal from the sprocket as read by the sensor. Let's just say, if the cam sprocket on the car that won't start had 12 hash marks, and the sprocket on the car that does start has 8, the sensor doesn't care, it just reads it and feeds the info into the computer. BUT, if the computer is calibrated for 8 and there are 12, it's not going to run because it's not seeing what it needs to see.

The 180 off doesn't matter because you aren't setting the engine to #1 TDC, as I said, lining up the crank just pulls the pistons into the block away from the valves.

Customer: replied 11 months ago.
Bot***** *****ne is, if the sensors were bad, they would not start the 2008, correct?
Expert:  Mike V. replied 11 months ago.


I don't believe the sensors are the issue. I would find out if its lacking spark doing a regular spark check if you haven't and also check the plugs for gas on them. OR use a noid light for injector pulse which would be a better method.

Also, check it for codes if you can. If the problem is with the cam or crank sprocket being different, she should throw a code for the cam or crank sensor.

Customer: replied 11 months ago.
No sprockets were ever interchanged, so I don't think there is an issue there.I'm still hung up on the timing, maybe I'm not explaining correctly....Woodruff key at 6-oclock all timing marks line up and pistons are about half way through their stroke. Lets say #1 piston, which is the front left if you are standing in front of the engine bay is half way in the cylinder at the timing mark alignment. Lets say that when you lined up your marks, #1 was traveling from the crank toward the spark plug. (even though it is now stopped mid way through it's stroke, it's direction of travel would be toward the spark plug. If you turned the crank pulley one full revolution, piston #1 would now be traveling from the spark plug toward the crank shaft and if the crank sensor thought that it was at TDC, it would fire but in reality the piston would be at bottom dead center, therefore it would not start.... Does this explain better?
Customer: replied 11 months ago.
If this were the case, then the firing order which starts at piston 1, would be 180 degrees out of time....
Expert:  Mike V. replied 11 months ago.

No, that's the point, the engine you removed was an 08 with an 08 computer. You installed a '10 engine, it's possible the sprockets on the '10 engine are different.

I will open this up for the other experts, I can't do this.

Please don't reply or rate, then it will be locked to me.

Customer: replied 11 months ago.
what is a noid tester? Seen people referring to it on a forum, but don't know what it is? Just a test light with a ground and a probe?
Customer: replied 11 months ago.
I'll wait for another technician, but for clarity Mike, I put my 08 engine in the 2010 car with the 2010 computer and it ran great for 6 months while we awaited the 2010 motor to get rebuilt. I just put the 08 engine back in my 08 impreza, and the rebuilt engine is the original that I took out of the 2010 to begin with. I did not change any ecm's between the cars, only the engines.
(Reason for the original swap was that I had to put a clutch in the 08 so it had to come out anyway, and we wanted to drive the 2010 while waiting for the 2010 engine to get rebuilt)
Expert:  sprinkles08 replied 11 months ago.

Hello and welcome to JustAnswer!

Do you still need help?

Customer: replied 11 months ago.
I got it figured out and after reading Mikes responses, I see that he did state that perhaps the crank pulley or cam pulley were wrong. It was the crank pulley- engine shop had switched my crank pulleys on my ej20 and ej25- had them do an ej20 for me also. By rights, mike mentioned it therefore I wanna credit him. How do I do that?
Expert:  sprinkles08 replied 11 months ago.

You should be able to highlight one of his responses and rate his performance. OK service or higher will give him credit.