Crank & Cam Sprocket differences

[shmick]

Hey folks, new to the forum and hoping to get some clarification on an issue I'm having.

 

I just did a like-for-like engine swap in my '05 2.5 RS. The '05 donor engine was married to an auto transmission. My car is a 5 speed.

 

After the engine swap, I'm throwing a P0340 (cam sensor) CEL and have determined that the sensor, wiring and timing are all fine.

 

I just got back from talking to a tech a Subaru dealership and was told that the crank and cam sprockets are slightly different on cars that come from Automatic transmissions vs Manual transmissions, and he said that's why it's throwing a cam sensor CEL.

 

I've been trying to confirm that this is the case before I spend another 4 hours removing and replacing parts, but I haven't found anything to suggest that there is a difference between the crank and cam sprockets.

 

Hoping someone can provide some insight.

 

Thanks and Happy New Year!

 

[Fairtax4me]

Does the engine start and run?

 

If it runs and you have a cam sensor code it's because the timing is off by a tooth.

 

If it doesn't start, it could be the sprocket.

The major difference is the number of notches on the back of the sprocket that the cam sensor reads. If you get the wrong sprocket you will have no spark because the ECU doesn't know which cylinder is at TDC.

[shmick]

Yep, the engine starts and runs. On a scale of 1-10, it's running at about 8.5. It hesitates just a little off the line, but it's not too bad.

 

The timing is not off. I checked the timing on the original belt that was on the donor engine and also ended up putting a brand new timing belt on.

 

When I went to the Subaru dealership today, I told the tech what was going on and he immediately asked if the donor engine came from an Auto or Manual and then asked me what my car is. When I said my car is manual and the donor engine came from an Auto, he said that I need to swap the crank and cam sprockets from the original to the donor engine. I'm prepared to do this, I'm just trying to confirm that his prognosis is correct before I start ripping things apart again.

 

I've yet to find any info online that says there's a difference in crank and cam sprockets on an EJ253 between Auto and Manual transmissions.

[john in KY]

That there would be a difference  based on which transmission was installed makes no sense to me. 

[johnceggleston]

makes no sense to me either, but they do have different part numbers,

and engine ID numbers,

and they are trans specific.

 

swap the cam sprocket and i'll bet the CEL goes away.

 

EDIT: (1 day later) upon further research, it does not look like the cam and crank sprockets are different.

i should have looked into it more in the beginning.

Edited January 3, 2014 by johnceggleston

[Fairtax4me]

The only difference I can imagine is that maybe one is clocked slightly more advanced than the other. Engineers often specify different idle speed settings and ignition timing advance settings for auto vs manual because of the different amounts of load on the engine. Its all for emmissions regulation. Not hard to imagine maybe they have slightly different cam timing as well, especially on the newer stuff.

 

 

Double double check the timing belt. Be absolutely sure the crank is right, and the cam marks are lined up with the seams in the heads, don't go by marks on the belt because they can be wrong.

If you're completely sure the timing is right, swap the sprockets and see what you get.

[shmick]

Yep, I'm absolutely certain that the timing is ok. Timing marks on the sprockets lined up with the engine marks and I also verified belt tooth count prior to installing. It all lined up as it should.

 

I guess the only thing to do at this point is try the cam & crank sprocket swap and see what happens. I'll be sure to take pics and report back when I get to it. Probably next weekend. Till then, I'll continue to scour the 'net to see if there's any documented difference between the sprockets.

Edited January 3, 2014 by shmick

[86BRATMAN]

Check on opposedforces.com and see if the part number is different between manual and auto.

[shmick]

I didn't see any differenced on opposedforces, but here's what I did find.

 

A youtube video of a timing belt being done on a 2002 forrester with a 2.5i, has a sprocket that looks like this:

 

 

 

Here's a photo I took of my original engine after I pulled it from the car.

 

 

 

Youtube video:

 

Edited January 3, 2014 by shmick

[86BRATMAN]

Some of the early phase 2 ej25s used the phase 1 style triggers, which is what the 02 forester shows there. If your replacement engine had the old style it shouldn't start at all because the ecu wouldn't be seeing the inputs it expects so it wouldn't know when to fire. This is what fairtax was talking about earlier.

[idosubaru]

there are two different style of triggers, that's well known.  i've never know that difference to be isolated to an auto or manual thing though but maybe it is?

[johnceggleston]

have you tried the cam sensor from the old engine?

 

in reviewing the part numbers and usage for the 05, ej25 sohc cam sprocket,

it was first used on the 99 ej22, and then on the 03+ ej25 , possibly until today?? but i don't know.

so it appears that the 00 - 02/3 ej25 sohc cam sprockets are different.

 

but if the sprockets on these engines are the same , (05 RS auto vs. 05 RS manual)

then maybe the sensor, connector, or wiring.

Edited January 3, 2014 by johnceggleston

[ivans imports]

Also is two timing belts one for ej2.2 and one for ej 2.5 is slight diff on the cam timing mark if the 2.2 belt is on a 2.5 the ds cam will be slightly retarded and could cause this also check that cam sprocket is running true have seen a bent one cause this sometimes if engine was hit or droped on sprocket

[shmick]

Yep, I swapped both the cam and crank sensors from both engines and it didn't make any difference. Both the original and donor engine are 2005 EJ253.

 

Just spoke with the Subaru tech again at the dealer. He said that if I'm chasing down a cam sensor problem that didn't exist with the old engine, that it's most likely due to either the crank or cam sprocket. He said that if the ECU throws a CEL for the cam position sensor, that the ECU will ignore the triggers on the cam sprocket and only use the triggers coming from the crank sprocket.

 

He also said that he's pretty certain that there are different crank and cam sprockets for MT and AT vehicles. Maybe this is a Canada specific thing?

Edited January 3, 2014 by shmick

[Fairtax4me]

Did you swap the intake manifold from your old engine onto the new one? Or remove the intake manifold on the new engine for any reason?

 

Trying to figure if the wires for the Cam sensor might be pinched under the manifold.

Also (I should have thought of this before) check the pins in the big connectors on the bellhousing. Make sure none are bent or backed out of the connectors. And make sure the connectors are completely plugged in.

[idosubaru]

1. swap original cam and crank sprockets on new engine

2. swap original cam and crank sensors onto new engine

3. ensure it's the same timing belt as the original engine

 

Then all the ignition/timing related hardware is identical to the old engine.

 

If there's still any hesitancy, then swap the intake manifold - then all the wiring is for sure identical as well.  But that shouldn't be necessary.

 

 

Let's re-verify engines:
Original Engine:  2005 EJ25 Impreza RS  Manual transmission

Donor Engine:     2005 EJ25 (Model????)  (Trim????)  Auto

Edited January 3, 2014 by grossgary

[shmick]

Throttle body & intake manifold were not swapped. Only the flywheel, clutch and timing belt guide were swapped over.

 

Once the troubleshooting for the P0340 cam position sensor began, the cam sensor was swapped over, then the crank sensor was swapped over and then the alternator was also swapped over.

 

There doesn't appear to be any damage to the donor engine wiring harness. I did check for continuity from the cam sensor plug wires back to the large brown 16 pin E1 connector. I also checked resistance between pin1/pin2 pin1/ground and pin2/ground on the cam sensor plug. Everything is within spec.

 

Donor engine is also from a 2005 2.5 Impreza RS, at least I'm assuming it's an RS since it's got SOHC. The seller said the engine was pulled from a vehicle that was in a rollover collision.

[Fairtax4me]

All N/A 2.5s changed to SOHC in 2000.

If the engine looks identical and the plugs on the bellhousing actually plug in then I dont see there being an issue with engine compatability.

[idosubaru]

Throttle body & intake manifold were not swapped. Only the flywheel, clutch and timing belt guide were swapped over.

 

Once the troubleshooting for the P0340 cam position sensor began, the cam sensor was swapped over, then the crank sensor was swapped over and then the alternator was also swapped over.

 

intake should not matter, that would be a last resort in my book.

 

It looks like of steps 1-3 i posted above you've only done #1 and I'd consider #2 to be the most important.  Swap those and it should be identical engines as far as the ECU is concerned.  At that point the only possible differences could be wiring on the intake manifold which seems unlikely since they are plug and play parts.

[idosubaru]

 

If the engine looks identical and the plugs on the bellhousing actually plug in then I dont see there being an issue with engine compatability.

YES YES YES - THIS!  This should be simple - not complex, I wouldn't spend inordinate time diving into compatabiliity issues.  There is one known significant issue that you haven't tried yet (swapping sprockets), that's it.

 

****Swap the *sprockets*, not the sensors.

 

if the crank and cam triggers (sprockets) are the same or swapped then something else is doing on and it's likely not a compatability issue.  EJ25's are swapped all the time so there shouldn't be anything magical about this (alternate markets notwithstanding).

well said fairtax.

Edited January 3, 2014 by grossgary

[shmick]

 

intake should not matter, that would be a last resort in my book.

 

It looks like of steps 1-3 i posted above you've only done #1 and I'd consider #2 to be the most important.  Swap those and it should be identical engines as far as the ECU is concerned.  At that point the only possible differences could be wiring on the intake manifold which seems unlikely since they are plug and play parts.

 

#1 and #3 were done. When the new belt was installed, the timing marks were compared to the old belt as well. The old belt didn't need to be replaced but it turns out that we didn't install the small belt guide properly and it started to rub/wear into the timing belt. As a precaution, we ended up changing the timing belt as it would have mentally nagged me to to end!

 

OK, looks like next steps are sprocket swap and if that doesn't fix it, I guess I'm doing wire harness swap!

 

Also, thank you to everyone who's contributed to this thread. Lot's of helpful folks here. Greatly appreciated.

Edited January 3, 2014 by shmick

[idosubaru]

#1 and #3 were done.

 

Good..sort of, i think there's much hope then.  #1 is never an issue really and #3 isn't an issue either - aside from a known 99-ish era difference.

 

It's a WAG but #2 is the most common issue for Subaru EJ25's so i think it's time well spent.

[johnceggleston]

my only concern is that usually the wrong cam causes a no start situation, doesn't it?

[86BRATMAN]

That has been my impression from other threads I've read.

[idosubaru]

hhhmmm, that sounds familiar.  i've swapped gears so i don't know the actual symptoms.

i honestly thought the trigger differences were only 99-04 models only but that was purely assumption...man i'd really like to "know" what year/vehicle/model gets the different triggers.

 

maybe 05's are different given the ECU and other changes?