P0303 Cyl#3 misfire HELP!

[pdeltoid]

Hi - I'm new here, appreciate all the info on these boards. I know a lot of people have asked about this, but maybe mine is different.

 

I have a 97 outback wagon 2.5L, 138,000 miles. Automatic.

 

Car continues to throw the CEL with a code of P0303. First time it did it, I replaced the plugs, but with autolites or something like that. I have read here about using only NGK.

 

After changing the plugs, the light came back on after about a week or so. Next I changed the wires (auto-zone ones). Light went out, but came back. Understood that the 2.5 is funny about wires, so bought the japanese wires from the subaru dealer. Light went out, but came back. I don't think its the wires.

 

I have tested the coil with the water spray test, no sparks.

 

I have swapped fuel injectors from 1 to 3 and the code came back, stayed with #3! The fuel injectors looked fine. I also changed the fuel filter at the same time.

 

The car idles rough at about 500rpm, engine shudders the whole vehicle at stop lights. This goes away after the car warms up and after about 10 miles. My gas mileage has also dropped. Also, I noticed the exhaust smells more like fuel than it used to.

 

I have not checked compression, is that something easy to do? I guess I need to look around for a test kit.

 

Read on here that people have had success by changing the O2 sensor, the one on board is probably original. Not sure as I have had the car for about 20k. Timing belt was changed (according to the records i have) at 88k (50k ago).

 

I plan to replace the current plugs with NGKs soonest and see what happens.

 

Any ideas? I don't want to continue troubleshooting this thing by swapping parts out, and I have limited mechanical ability, but have limits. This is frustrating, not sure if its an ignition, fuel or mechanical problem. Any help from you guys would be great.

 

Thanks for your time,

Mark

[Cougar]

Since you state that the engine may be running rich the problem may be due to a bad coolant temperature sensor for the ECU. This is not the one for the dash gauge. These sensors can fail so that the ECU thinks that the engine is cold when it is really hot. If it is bad this may be causing the misfire code also.

[tcspeer]

Another suggestion is to check the # 3 plug with a inline plug checker to see if you have fire, then check that # three injector pigtail with a noid light, I had this same problem with cyc. three misfire and mine turned out to be the E.C.U. (computer). I had no flash to this inj. pigtail but I had volts to the pigtail.

[pdeltoid]

Thanks to both of you - I hadn't thought of either of those two options.

 

Cougar - where abouts is the coolant sensor? My manual shows i can test the resistance in it to see if it is good.

 

TCSpeer - I will try to get you those checks tomorrow - Can I check the injector pigtail with a multi-meter? I dont have noid lights.

 

I'll let you know what happens.

[Cougar]

The sensor should have two leads going to it and I think it is on the passenger side of the engine. Possibly behind the throttle body area. You can also see if the voltage changes across the sensor as the engine warms up.

 

You can use a voltmeter to check the injectors but it may give a funny reading since the signal is pulsed.

 

You are welcome for the help.

[lmdew]

Mark if you want to try the coolant temp sensor I have the one that came off the same engine as the injectors. Larry

[tcspeer]

Pdeltoid, you can check to see if volts are at the pigtail with multi-meter, but to check the E.C.U. you will need the noid light, as cougar says any reading you get would probably be funny, and most likly useless.

[Gloyale]

you will need the noid light, as cougar says any reading you get would probably be funny, and most likly useless.

 

 

use a cheapo test light probe. Connect the clipped lead to the +POS side of the battery. Then use the pointed end to probe the negative wire on the injector. tart car and Watch for the bulb to pulse.

[pdeltoid]

I'm actually working on the car now, taking a break.

 

I checked cyl #3 with the in-line checker, it checked out OK, the in-line checker was flashing consistently, even when it threw the code (same one 0303).

 

Also got a noid light box from auto-zone on loan, and checked the fuel injector harness, and that flashed too, seems to be OK.

 

I am going to do a compression test now and see what I come up with, will post results here.

 

I'll put the NGK plugs in after I finish, and drive it to work tomorrow to test. I am going to check the other fuel injector harnesses too, since I have the noid lights, might as well rule that out while i am at it.

 

Haven't gotten to the engine coolant sensor yet, that will probably be tomorrow.

 

Mark

[pdeltoid]

OK - I think i have bad news...

 

Here is the compression test results (did it with a cold engine, all plugs out):

 

#3 - 65

#1,2,4 - all between 140-150

 

Since #3 is the problem one, and had a number so far off, i did the "wet" test by squirting some oil in the spark plug hole and re-doing it. I got 80.

 

From what I read, that means rings or cylinder is bad, not the valves.

 

At least I think that isolates the problem anyway. Question is: what next?

 

I assume that means an engine overhaul, not sure if that is worth it. How far can I drive this thing before it dies? How much is that going to run me?

 

Thanks for your help,

Mark

[Cougar]

There may be some hope here. I suggest you purchase a product called AutoRx and see if it will help with this problem. It has freed up gumed up rings to get the compression back and given more life to leaking gaskets also. Here is a link to the site:

 

http://www.auto-rx.com/

[lmdew]

You can always drop a 95 2.2 into it. Larry

[OB99W]

[...]Here is the compression test results (did it with a cold engine, all plugs out):

 

#3 - 65

#1,2,4 - all between 140-150

 

Since #3 is the problem one, and had a number so far off, i did the "wet" test by squirting some oil in the spark plug hole and re-doing it. I got 80.

 

From what I read, that means rings or cylinder is bad, not the valves. [...]

In my experience, the difference between 65 lbs and 80 lbs dry-vs-wet compression isn't enough to be certain of the cause, especially when run on a cold engine; there are things that can cause that much variation from test to test other than the added oil. A leak-down test on #3 with listening to determine where the air is going would be much more definitive.

 

While head work isn't cheap, it would be considerably less than dealing with the block. A good used engine might be the answer if serious work is otherwise needed.

[Gloyale]

OK - I think i have bad news...

 

Here is the compression test results (did it with a cold engine, all plugs out):

 

#3 - 65

#1,2,4 - all between 140-150

 

Since #3 is the problem one, and had a number so far off, i did the "wet" test by squirting some oil in the spark plug hole and re-doing it. I got 80.

 

From what I read, that means rings or cylinder is bad, not the valves.

 

Hmm. not good.

 

But you've got the diagnosis backwards.

 

If the rings were bad, a *wet* test would seal them and bump up pressure. That is provided the valves sealed tight.

 

Since the wet test made no real difference, that means a valve is leaking. Although a proper leakdown would be the best test. But sounds to me like you need head work.

[pdeltoid]

OK - I thought that a difference from 65 to 80 was significant enough to tell. I guess you are right, looking at it again.

 

Might call around tomorrow to ask about a valve adjustment.

 

Something mechanical anyways, now to figure out what!

 

Thanks.

[OB99W]

[...]Might call around tomorrow to ask about a valve adjustment.[...]

I'd still suggest running a leak-down test, to verify it's valve-related. Valve adjustment might be called for, but a burned valve could explain the compression loss and adjustment isn't going to resolve that.

[Gloyale]

Hopefully it's not from something like this.

 

http://www.ultimatesubaru.org/forum/search.php?searchid=542786

[pdeltoid]

Hopefully it's not from something like this.

 

http://www.ultimatesubaru.org/forum/search.php?searchid=542786

 

Nothing comes up from that link

[pdeltoid]

Regarding the leak-down test:

 

I assume I really only need to do the test on Cyl #3, right?

 

From what I understand, that cylinder needs to be at TDC, how do I do that?

 

I am still looking around for a leak-down tester kit, doesnt seem to be too hard to do once I get that.

 

Yesterday I discovered an oil leak from the pass side of the timing belt cover, probably one of the seals inside leaking, maybe causing the timing belt problems. Looks like I have more work to do.

 

I might end up just swapping this thing out anyways, then rebuild it. Another project I dont have time for.

 

Mark

[OB99W]

Regarding the leak-down test:

 

I assume I really only need to do the test on Cyl #3, right?

Yes, assuming you're just trying to determine why the compression is low in that cylinder.

 

 

From what I understand, that cylinder needs to be at TDC, how do I do that?

Using the timing scale at the front of the engine, rotate the crank in the direction of normal running (clockwise, viewed from the front) until the mark is at 0 degrees. If that doesn't result in cylinder #1 being at TDC, then rotate one more full turn (360 deg). Since the firing order is 1-3-2-4, turning the crank in the direction of normal running an additional half turn (180 deg) will put cylinder #3 at TDC. If you intend to apply significant air pressure, the engine should be locked in that position during the test.

 

 

I am still looking around for a leak-down tester kit, doesnt seem to be too hard to do once I get that.

For the testing you need to do, the "kit" doesn't have to be very sophisticated. In fact, only a means of applying air at low pressure (about 20 psi) to the plug hole is all that's required; keeping the pressure low lessens the need to lock the engine to prevent air pressure from rotating it. Gauges would give readings that permit comparisons, but all you have to do is determine where the air is leaking. Listen at the exhaust, crankcase (remove the oil filler cap), and intake to determine where the air is going. (If bubbles are formed in the coolant, that indicates a bad HG, but you'd have other symptoms if that was the case.)

 

As long as the air is escaping only to either exhaust or intake, the work needed will be on the head, not the block.

[pdeltoid]

OK, did the leak test this morning - pretty slick! The air is leaking back through the exhaust. I understand this means there is a bad exhaust valve, correct?

 

What am I looking at here to fix this?

 

Does this mean pulling heads and therefore the engine to fix this?

 

I think my cam seals are leaking as I have oil leaks at either side of the timing belt cover.

 

Other option would be to pull and swap with a 2.2.

 

Any ideas here on comparisons of the 2 jobs, cost wise and effort wise?

 

Thanks

[johnceggleston]

OK, did the leak test this morning - pretty slick! The air is leaking back through the exhaust. I understand this means there is a bad exhaust valve, correct?

 

What am I looking at here to fix this?

 

Does this mean pulling heads and therefore the engine to fix this?

 

I think my cam seals are leaking as I have oil leaks at either side of the timing belt cover.

 

Other option would be to pull and swap with a 2.2.

 

Any ideas here on comparisons of the 2 jobs, cost wise and effort wise?

 

Thanks

 

the guys who are good at head gaskets just shake their heads when we start talking 2.2 engine swaps. they're all about fixing the engine you have. on the other hand when you buy an outback with bad head gaskets and you don't know how badly it was abused or overheated it could be smarter to do the swap.

 

i've heard head gasket prices (you have to do this to do the vavle work) from 900$ to 1500$, 1200 to 1500 more common. and engine swap prices from 500$ to 1200$ depending on the price of the 2.2 engine. the labor to swap should be a day or less. ball park numbers.

 

since you know your engine hasn't overheated, it would seem a good candate for doing the valve / gasket work. if you had a good 2,2 sitting in the backyard that maght be a better solution.

[davebugs]

No matter what you do I'd do the TB, idler pulleys, waterpump, etc while the engine is out and easy access. Probably crank and cam seals as well.

 

I've done one 2.5 HG job and am about done with my first 2.2 conversion.

The parts/gaskets, getting the heads checked, etc starts to add up fast on the 2.5. I balance that with keeping the original engine.

 

Dave

[pdeltoid]

Well, just an update for you all.

 

First, thanks to everyone, especially lmdew for their help.

 

I ended up pulling the engine, having a valve job done. I replaced the Water pump, fixed up the oil pump (3 screws were half out!), new t-belt and idlers, new hoses and thermostat. Ended up have to replace 2 valves and all the valve guides as well. The heads were in great shape though, so that was nice.

 

Found out that the problem was a leaking exhaust valve on #3, most likely caused by poor valve adjustment. That led to the poor compression and misfire on #3. The compression test, leak-down and vacuum tests confirmed all this before tearing it apart.

 

It took me quite a while to get it done as I was waiting for parts, and working etc.

 

First time I have ever done that much to an engine myself, but it wasn't too hard using the subaru factory service manual.

 

Got it started this morning before work; It seems to be running well and the valve adjustment helped get rid of the ticking noise.

 

I do have a couple of requests/quetions that I'll put in a separate post.

 

Thanks again!

 

Mark

[Olnick]

Way to go, Mark. Congratulations! Please do keep us updated down the road.