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P0301,2,3,4 misfire - '97 Legacy 2.5


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18 replies to this topic

#1 guysk

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Posted 23 September 2006 - 11:38 AM

Hi all,

My Subaru is putting out cylinder misfire codes for all four cylinders, P0301,0302,0303, and 0304. I am looking for some help in diagnosing it further. Here are the things that I replaced so far:

o coil pack
o plugs
o wires,
o PCV valve
o fuel filter
o air filter
o timing belt
o water pump
o knock sensor (had code P0325)

This started to occure within a few weeks or so of having my timing belt and water pump changed because of a sqealing timing belt pulley.

I reset the light numerous times and it comes back on around 20 to 50 miles later. I can't notice any rough running when the light flashes. If I read the code shortly after the light comes on then I don't always get all the cylinder misfire codes but if I drive it a couple hundered miles then they all get set (P0301-4).

Just today I noticed that the air conditioner belt was very loose and I know that it was tight a few days ago. I re-tightened belt expecting something to be loose in the tensioner mechanism but found everything snug. That seemes odd.

I also noticed today that the crankshaft pully is not well balanced. When it spins, it is out of round - not grossly out of round but more than I am comfortable with.

Any ideas on where to go from here would be greatly appreciated.

'97 Legacy Outback 2.5L
177,000 miles
32MPG

#2 nipper

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Posted 23 September 2006 - 01:17 PM

what brand ignition wires?

nipper

#3 ferret

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Posted 23 September 2006 - 01:49 PM

I would go back to the timing belt. Bet it's off by a tooth. This WILL cause a misfire on ALL cylinders as you describe.

I would go back to where you had the work done and ask them to check it.

#4 grossgary

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Posted 23 September 2006 - 01:52 PM

exactly what nipper said. if you didn't use Subaru OEM wires, then that is most likely your problem.

#5 OB99W

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Posted 23 September 2006 - 01:54 PM

[...]Just today I noticed that the air conditioner belt was very loose and I know that it was tight a few days ago. I re-tightened belt expecting something to be loose in the tensioner mechanism but found everything snug. That seemes odd.

I also noticed today that the crankshaft pully is not well balanced. When it spins, it is out of round - not grossly out of round but more than I am comfortable with.[...]

The codes can be dealt with later; right now you need to deal with the crank pulley situation. It's very likely that either the pulley bolt is loose (check that first), or the pulley is coming apart (it's 2 pieces of metal with rubber isolation between them). That's probably why the A/C belt suddenly loosened and the pulley seems "not well balanced".

If the pulley bolt is loose and remains so, it can destroy the front end of the crank (keyway, etc.). If the crank pulley itself is bad, it can do damage to other parts.

Either way, don't delay in resolving the problem. Once you do so, deal with the other problems.

#6 grossgary

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Posted 23 September 2006 - 01:56 PM

OB99W, good job! i forgot to mention that. i agree with his sentiments exactly. get that crank pulley checked out or replaced immediately. you can post a picture of it here if you'd like us to look at it. sounds like it's beginning to separate. you can draw a line across the entire diameter of hte pulley, then check it after running the car. the line will appear to have been "broken" if the pulley is beginning to separate (which it sounds like it has). if this is the case, replace it immediately.

#7 guysk

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Posted 23 September 2006 - 02:19 PM

I will check the crank pulley this afternoon. I wonder if it was damaged when it was removed to change the timing belt? I noticed that a small piece of metal was missing from the back where the belt goes around (~1/16" x 1/2"). I will take your advice and deal with the crank pulley first. That sounds more serious than I thought.

The wires are OEM wires and I replaced them after the codes started appearing with no change in the results.

If the timing belt were off by a tooth wouldn't that cause the engine to run very rough? It seems to be running fine, although, the idle is not as smooth as it should be. It starts fine and under load seems to be at full power. The gas mileage is also great (32MPG) and hasn't changed; I keep track of it pretty well.

How do I check if the timing belt were off by a tooth? I would take it to the guy that changed the belt but it is a major hassle to get the car there so I would rather check it myself.

#8 grossgary

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Posted 23 September 2006 - 02:29 PM

i would check the crank pulley first and go from there. describe this missing piece of metal. or take a picture. is it the crank key?

i doubt it's the timing belt. i wouldn't expect it to run that good if it were off a tooth. and sounds like the plug and wire install went well. there weren't any glitches that you know of during the timing belt or plug/wire install?

if a timing belt tensioner had issues that may cause something, but i'm not sure about that.

#9 guysk

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Posted 23 September 2006 - 02:44 PM

It's not the crank key, it is at the outside back edge of the pulley just beyond the belt contact area.

As far as glitches during the timing belt replacement. The belt tensioner and one of the pulleys, I can't remember which one but I have the old part, were bad. The pulley and tensioner were replaced with ones from the salvage yard. I didn't personally check them myself but my mechanic checked them and he thought that they were just fine. I trust him completely. $50 at the junkyard compared to ~$250 new and no waiting for the parts to get delivered.

#10 OB99W

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Posted 23 September 2006 - 02:53 PM

I will check the crank pulley this afternoon. I wonder if it was damaged when it was removed to change the timing belt? I noticed that a small piece of metal was missing from the back where the belt goes around (~1/16" x 1/2").[...]

It's possible it was damaged during the t-belt work; the crank pulley bolt torque is quite high, and someone may have used an inappropriate method of restraining the crank pulley from turning.


[...]How do I check if the timing belt were off by a tooth?[...]

For reference (you may not want to get this deeply involved):
http://endwrench.com/images/pdfs/TBeltEWWin05.pdf
http://endwrench.com/images/pdfs/2.5Timing.pdf

#11 nipper

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Posted 23 September 2006 - 03:17 PM

What they said, sorry i missed the loose pully and timing belt thing, pulley first, then timing belt. Do not drive the car with a loose pully, dont even run it more then you need to.

nipper

#12 guysk

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Posted 24 September 2006 - 02:07 PM

You guys made a good call! The crankshaft pulley was loose.

I removed the crank pulley and the keyway on the pulley was ground around almost to about a half circle. The key on the crankshaft is slighlty bent and not very square any more but at least it isn't completely gone.

I searched the archives and it seems that in my situation the best thing to do is to do is remove the crakshaft sprocket, replace the key, replace the crankshaft pulley and torque it tight. Is that correct and is there anything else that I should be concerned about beside checking the pulley torque for a few weeks? The problem with this soution is the time the car will be down and I don't care to remove the timing belt and deal with all that.

So, why can't I just bore two holes in the pulley that match the holes in the crankshaft sprocket and add two steel pins and tighten it well? That way I don't have to pull the timing belt off. I know this is a bit of a cludge but it seems to be a better idea than the way it was designed in the first place. Is there any reason not to do it this way?

#13 OB99W

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Posted 24 September 2006 - 03:37 PM

You guys made a good call! The crankshaft pulley was loose.

I removed the crank pulley and the keyway on the pulley was ground around almost to about a half circle. The key on the crankshaft is slighlty bent and not very square any more but at least it isn't completely gone.[...]

There's an entire series from Motor magazine covering both the 2.2 and 2.5 timing belts. It includes some very specific claims about loose crank pulley bolts and the relationship to previous timing belt work; I'm sure you can guess what they said, but I'd suggest reading all the articles, as there is some good info in general. See:
http://www.motor.com/MAGAZINE/Pdf/072001_08.pdf
http://www.motor.com/MAGAZINE/Pdf/082001_08.pdf
http://www.motor.com/MAGAZINE/Pdf/092001_08.pdf
http://www.motor.com/MAGAZINE/Pdf/102001_08.pdf
http://www.motor.com/MAGAZINE/Pdf/112001_08.pdf

Someone whose Subaru has a loose crank pulley with related damage might consider printing out the articles and presenting them to a mechanic who did the previous timing belt work. :brow: It would seem that the owner shouldn't have to deal with the problem. Of course, whether the same mechanic can be trusted at this point is another story.


So, why can't I just bore two holes in the pulley that match the holes in the crankshaft sprocket and add two steel pins and tighten it well? That way I don't have to pull the timing belt off. I know this is a bit of a cludge but it seems to be a better idea than the way it was designed in the first place. Is there any reason not to do it this way?

There used to be a kit to repair the damage, similar in manner to what you're suggesting. Unfortunately, I can't seem to find a link to that now. Anyone else have info on this?

#14 Olnick

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Posted 24 September 2006 - 04:24 PM

There's an entire series from Motor magazine covering both the 2.2 and 2.5 timing belts. It includes some very specific claims about loose crank pulley bolts and the relationship to previous timing belt work; I'm sure you can guess what they said, but I'd suggest reading all the articles, as there is some good info in general. See:
http://www.motor.com/MAGAZINE/Pdf/072001_08.pdf
http://www.motor.com/MAGAZINE/Pdf/072001_08.pdf
http://www.motor.com/MAGAZINE/Pdf/092001_08.pdf
http://www.motor.com/MAGAZINE/Pdf/102001_08.pdf
http://www.motor.com/MAGAZINE/Pdf/112001_08.pdf


Thanks 99OBW--nice articles, well written. The author's style helps me understand the "why's" better.

(But I think the 2nd installment may be missing. The link calls up the 1st article again!)

#15 OB99W

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Posted 24 September 2006 - 05:09 PM

Thanks 99OBW--nice articles, well written. The author's style helps me understand the "why's" better.

(But I think the 2nd installment may be missing. The link calls up the 1st article again!)

Thanks; here's the correct link for the 2nd part (I also edited my post above, and gave you credit :) ).
http://www.motor.com/MAGAZINE/Pdf/082001_08.pdf

#16 guysk

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Posted 24 September 2006 - 05:17 PM

I just finished the modification of adding two pins in the crankshaft pulley to match the two holes in the crankshaft sprocket. I temporarily tighted the crank pulley (not full torque yet because I wanted to see if it worked first) and ran it with no belts on. The good news is that the pulley runs true with no wobble. But...

It idles smooth and runs smooth at any RPM. The problem is that I hear some ticking when I give it a little throttle and let it off. As the RPM drops through about 1000 or so, there is some significant tapping noise for about a second until the throttle stays at a consistant RPM. What is it? I don't know for sure but I don't think that noise was there before. I am not sure if I should put it back together and let it go or if I should find out if I have a more serious problem caused by the wobbly pully in the first place.

Here is how I did the mods in my non-machine shop. I never removed the timing belt, although it would have been easier, as I carefully measured the location of the holes in the crankshaft sprocket. Then I transfered the hole centers to the crank pully and drilled both holes on my drill press all the way through. The holes on the sprocket were slightly bigger than 1/4" but all I had for pins were some 1/4" bolts. The drilled hole size was whatever I needed so I could tap 1/4" threads into it, which I did. I cut the head and some of the threads off the bolts so that I could thread them all the way in to the non-threaded shaft of the bolt. The pin part is about an inch long. I used some blue locktight and tightened them into the crank pully very well. After that, I installed the pulley and viola, no wobble.

But I still have some noise...

#17 Mikevan10

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Posted 25 September 2006 - 11:23 AM

I don't have any suggestions as to your noise, guy, but I must give you credit for your ingenuity and take charge approach! I am also amazed that this has not generated a torrent of comments. For example, will your mods result in dynamic balance errors? Will the clearance in the pin holes in the crank sprocket be problematic (considering that with the original keyed arrangement it is a snug fit)? Is the fact that you are now relying on the crank sprocket to resist any relative twisting between the crank and the pulley OK? Have you weakened the pulley enough to be a risk? And on and on...

I am not saying any one of the above definitely is a problem. Maybe it's a perfectly satisfactory fix. Is that what you guys are all thinking or is everyone too shocked to make a comment?

Mike V.

#18 OB99W

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Posted 25 September 2006 - 12:27 PM

[...]For example, will your mods result in dynamic balance errors?

The holes in the crank sprocket are pretty near the crank's axis, and symmetrically located. Therefore, even if the "pins" aren't exactly placed (obviously, they're close enough for them to engage the holes) there shouldn't be much change in balance. In fact, the piece of pulley missing at the edge would likely have more of an effect.


Will the clearance in the pin holes in the crank sprocket be problematic (considering that with the original keyed arrangement it is a snug fit)?

The timing mark may not be able to be relied on as precisely. However, that doesn't affect actual engine operation.


Is the fact that you are now relying on the crank sprocket to resist any relative twisting between the crank and the pulley OK?

Proper tightening of the crank pulley bolt is what's supposed to stop relative motion between the crank and pulley. The keyways and Woodruff key are there primarily for location purposes; that's why things get messy if the crank bolt loosens.


Have you weakened the pulley enough to be a risk?

Probably not an issue, but I never say "never". :)


And on and on...

I am not saying any one of the above definitely is a problem. Maybe it's a perfectly satisfactory fix. Is that what you guys are all thinking or is everyone too shocked to make a comment?

So that brings us around to the "ticking"/"tapping" noise. I don't know offhand what's causing it, either; knowing the apparent area the noise is coming from might help with a diagnosis. Perhaps just tightening the pulley bolt to spec might help, if there's some relative movement between the pulley/crank/pins/sprocket. Things might even change once the A/C and other belts are reinstalled and tensioned.

Of course, if the noise was there before the crank pulley work, that's another issue. It could even relate to the question of whether the timing belt is properly installed.

#19 johnceggleston

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Posted 25 September 2006 - 12:33 PM

there are several good threads dealing with this repair. they range from gluing the thing back together with some "never will let go" locktite, to actually repairing the keyway with welding(?) and then fileing it back to perfect. it also included the 2 pin method mentioned here. look around.

the most important information is : crank pulley wobble is the symptom of the problem. the problem is under torque of the crank pulley bolt. so when you have the work done or do it yourself, learn enought to torque the bolt correctly.

i thought myne was a result of the previous owner not using a $0.79 tube of locktite. but no, it's all about holding the flywheel and correct torque. locktite may not hurt, but it won't prevent the problem.


I don't have any suggestions as to your noise, guy, but I must give you credit for your ingenuity and take charge approach! I am also amazed that this has not generated a torrent of comments. For example, will your mods result in dynamic balance errors? Will the clearance in the pin holes in the crank sprocket be problematic (considering that with the original keyed arrangement it is a snug fit)? Is the fact that you are now relying on the crank sprocket to resist any relative twisting between the crank and the pulley OK? Have you weakened the pulley enough to be a risk? And on and on...

I am not saying any one of the above definitely is a problem. Maybe it's a perfectly satisfactory fix. Is that what you guys are all thinking or is everyone too shocked to make a comment?

Mike V.






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