The Dreaded Misfire Saga Continues

[subsince77]

I have already posted a couple of long threads about this, so I won't give much detail. My 97 OBW MT has thrown 0303, 0304 codes off and on for a long time. I have done everything anyone has suggested over the years to no avail. Actually, there is one thing I have not done. I did buy a used ECU from someone on this site, and I never put it in. I think I will do that this week. I also have not replaced any injectors. It seems more like spark than fuel since it is always those two cylinders. I finally got a code reader, and every time it happens I just check the code and clear it. It basically never does it in everyday driving, but always does it on trips. You can never feel a miss, the car always runs well, and gets great milage.

 

But, for the last month, seemingly since it got warm I am getting more misfire codes than usual. Now it has even happened on short trips near home a few times. Either something is getting worse, or it has something to do with the temperature. It is still always #3 and #4. Could the fact that it's summer affect this problem in any way?

[Gnuman]

If you have a component that is marginal the higher heat of summer may make it fail more often.

 

Since I have not been following the saga, I offer you the advice of coilpack, igniter, and connections. . .

 

Make sure the connections are clean first, this is the cheapest. then see if replacing the ciolpack helps, or perhaps you can try the igniter first. Either of the two being marginal will show up more when driven for a distance, or when it is hot.

 

Oh, and #3 and #4 are both on the same circuit of the coilpack or the igniter. . .

[edrach]

I have already posted a couple of long threads about this, so I won't give much detail. My 97 OBW MT has thrown 0303, 0304 codes off and on for a long time. I have done everything anyone has suggested over the years to no avail. Actually, there is one thing I have not done. I did buy a used ECU from someone on this site, and I never put it in. I think I will do that this week. I also have not replaced any injectors. It seems more like spark than fuel since it is always those two cylinders. I finally got a code reader, and every time it happens I just check the code and clear it. It basically never does it in everyday driving, but always does it on trips. You can never feel a miss, the car always runs well, and gets great milage.

 

But, for the last month, seemingly since it got warm I am getting more misfire codes than usual. Now it has even happened on short trips near home a few times. Either something is getting worse, or it has something to do with the temperature. It is still always #3 and #4. Could the fact that it's summer affect this problem in any way?

When's the last time you replaced the sparkplugs?

[TheSubaruJunkie]

I vote for sparkplugs and wires. My legacy ran like crap when i bought it. It had a horrible missfire, so i bought new plugs for it. It ran like a dream after that, until about 3 months later when it started again. Turned out the wires had gone bad, replaced them and no problems since.

 

If it hasnt been done in a while, or if you don't know when the last time it was done... definatly get new plugs and wires.

 

-Brian

[McDave]

It would help if we knew what "everything" was done already. Coil would be my first guess. Here's some things you can do to help isolate the problem.

 

Swap #3 and #4 wires with #1 and #2 to see if the problem moves.

 

If that didn't change anything, Swap #3 and #4 plugs with #1 and #2 to see if the problem moves.

 

If that didn't change anything, Swap #3 and #4 injectors with #1 and #2 to see if the problem moves.

 

This last one is a long shot but what the heck, you've had the problem for a long time. It's possible your exhaust valve guides have dropped down and are holding the valve open at times. An easy way to tell if this is the case is to hook up a vacuum gauge with a long enough hose so you can watch it while driving the car. If the needle starts bouncing when it misfires, suspect the guides.

 

To check them you can drop your exhaust y-pipe and rotate the crank until the exhaust valves open on each cylinder. If they've dropped you will see the guide, a metal sleeve, sticking out past the head surface towards the valve head. You can use #1 and #2 for reference.

[subsince77]

Sorry for the lack of detail, I just didn't want to bore those that have been through this thing with me in the past. To answer a few of the questions: I replaced coil pack, plugs and wires last November.

 

I got in a new CCR engine in January, so presumably that would eliminate any valve issues. In fact, only the fuel and ignition systems stay the same with the new engine, and it continued to throw the same code,s in the same way, with the same frequency from day one with the new engine.

 

At that point I again replaced plugs and wires. I always use the right NGK plugs and OEM wires, except now I am using NGK wires. The NGK wires were installed on the recommendation of CCR because I don't seem to be able to get the right wires for this car from Subaru. It seems that in 97 the early model cars like mine had the coil with the female towers, then sometime that year they switched to male towers which are longer. For whatever reason, the wires you get from Subaru are too short and barely reach from plug to coil. You can't even put the wire into the little wire guides. You have to stretch it to reach. I always thought that was weird, but I have gotten several sets of wires from Subaru and all were the same length. So, CCR said they were too short too. They like the NGK wires, use them all the time, and I got those - they fit.

 

I have also replaced the fuel filters, air filters, the neutral switch, done a couple of seafoam intake cleans (old engine), put BG 44K through, cleaned all the engine grounds, etc., etc., etc., all to no avail. So that is what I mean by I have done "everything". I have done all the typical stock answer things for this problem. It's not bad wires or bad plugs. I doubt the new valves are giving me the exact same problems as the old ones. It still could be an injector problem, I just thought it would be odd for two injectors to have a problem at the same time every time.

 

I have not however, replaced the igniter or ECU. Questions about that: Would the misfire always happen on the same two cylinders if it was the igniter? That was why the coil was suspected last fall. Would there be any other noticeable symptoms if it was the igniter? Is an igniter something you should get from Subaru, or can I get it elsewhere? Is it worth throwing one at it?

 

An igniter, being electrical, would make sense to me to be having more problems when it is hotter outside.

 

Thoughts?

[idosubaru]

the ignition coil and igniter? i'd swap a used one in - there's hundreds of them laying around garages of USMB members all over the country. they're a dime a dozen and don't fail all that often. try a used one for a few dollars.

 

i'd replace them one at a time so you know which one was bad.

[McDave]

Sorry for the lack of detail, I just didn't want to bore those that have been through this thing with me in the past. To answer a few of the questions: I replaced coil pack, plugs and wires last November.

 

I got in a new CCR engine in January, so presumably that would eliminate any valve issues. In fact, only the fuel and ignition systems stay the same with the new engine, and it continued to throw the same code,s in the same way, with the same frequency from day one with the new engine.

 

At that point I again replaced plugs and wires. I always use the right NGK plugs and OEM wires, except now I am using NGK wires. The NGK wires were installed on the recommendation of CCR because I don't seem to be able to get the right wires for this car from Subaru. It seems that in 97 the early model cars like mine had the coil with the female towers, then sometime that year they switched to male towers which are longer. For whatever reason, the wires you get from Subaru are too short and barely reach from plug to coil. You can't even put the wire into the little wire guides. You have to stretch it to reach. I always thought that was weird, but I have gotten several sets of wires from Subaru and all were the same length. So, CCR said they were too short too. They like the NGK wires, use them all the time, and I got those - they fit.

 

I have also replaced the fuel filters, air filters, the neutral switch, done a couple of seafoam intake cleans (old engine), put BG 44K through, cleaned all the engine grounds, etc., etc., etc., all to no avail. So that is what I mean by I have done "everything". I have done all the typical stock answer things for this problem. It's not bad wires or bad plugs. I doubt the new valves are giving me the exact same problems as the old ones. It still could be an injector problem, I just thought it would be odd for two injectors to have a problem at the same time every time.

 

I have not however, replaced the igniter or ECU. Questions about that: Would the misfire always happen on the same two cylinders if it was the igniter? That was why the coil was suspected last fall. Would there be any other noticeable symptoms if it was the igniter? Is an igniter something you should get from Subaru, or can I get it elsewhere? Is it worth throwing one at it?

 

An igniter, being electrical, would make sense to me to be having more problems when it is hotter outside.

 

Thoughts?

Well that sure eliminated a bunch of possibilities!

 

I would still swap the injectors since that would be a 'free' check. Also take a very close look at the injector wiring harness while you're at it. Manufacturers often pair up the power feeds to the injectors while using individual grounds to trigger each injector. The positive wire junction may be buried in the harness, but a temporary short on either side of the junction could take out both injectors at once. A fsm wiring diagram might show that.

[subsince77]

the ignition coil and igniter? i'd swap a used one in - there's hundreds of them laying around garages of USMB members all over the country. they're a dime a dozen and don't fail all that often. try a used one for a few dollars.

 

i'd replace them one at a time so you know which one was bad.

 

I'm not quite sure what you are saying here. I did replace the coil with a brand new one last November. It didn't help. Are you saying to try another coil as well as an igniter? I get the find a used one part.

 

Is the igniter that little back box back by the firewall, or did they hide it under the intake someplace?

[EVOthis]

i had a similar problem a while back....make sure the connectors are on the correct fuel injector....

[edrach]

Is the igniter that little back box back by the firewall, or did they hide it under the intake someplace?

Yes. Small black gizmo mounted in the center of the firewall.

[subsince77]

i had a similar problem a while back....make sure the connectors are on the correct fuel injector....

OK, again, same issue before and after injectors were moved from old engine to new by CCR, so I imagine they are right, but how would I know that? Are they marked? It seems to me that some of the leads may have been marked with white tape, but I would have to look.

 

I put in the new (used) ECM tonight. I think I'll see if someone has a used igniter too.

 

Thanks

[edrach]

I think I'll see if someone has a used igniter too.

 

Thanks

Get me the number off your old igniter (or a good picture of it) and I'll send you one for $10 if you don't mind used (no guarantees since it will have come off a Pull a Part donor car). $10 should cover mailing and my cost at PAP.

[subsince77]

Get me the number off your old igniter (or a good picture of it) and I'll send you one for $10 if you don't mind used (no guarantees since it will have come off a Pull a Part donor car). $10 should cover mailing and my cost at PAP.

Let's see, $10 used, or $262 new, for a part I'm not at all sure I need? Hmmm...? OK! I'll find the number and get back to you - thanks!

[davebugs]

I responded on your other thread looking for an ignitor. I'm dis-assembling a car right now. I know it ran. Never took it down the highway but I know it ran.

 

Be about the same price. And you'd know a little more about it.

 

Dave

[OB99W]

OK, again, same issue before and after injectors were moved from old engine to new by CCR, so I imagine they are right, but how would I know that? Are they marked? It seems to me that some of the leads may have been marked with white tape, but I would have to look.[...]

White-taped leads go to the front (#1 and #2) injectors.

[subsince77]

The igniter on a 97 OBW MT, and a 99OBW AT, should be the same right? Any reason to think otherwise?

[unibrook]

Have you replaced your front O2 sensor yet?

[Gloyale]

inspect very carefully the insulation on the wires for the Injectors. I had a car with chronic misfire on 3+4, but ussually 3. The issue was resolved when I found that small nick in the insulation of the injector wire. It was very close to the connector, and near where the plug wire crosses over the fuel rail. The wire beneeth had a few strands cut frayed as well.

 

I can't say for sure. But since I dabbed some solder on the wire, insulated it, and moved the plug wire away from it slightly, there has been no problem, 7 months now.

 

I really think that these persistent misfire issues are from *noise* issues between the injector wires and the spark plug wires. Perhaps exagerated when wires don't fit right and run tight over the injector rails.

[subsince77]

Have you replaced your front O2 sensor yet?

 

Yes, Just last spring.

 

inspect very carefully the insulation on the wires for the Injectors. I had a car with chronic misfire on 3+4, but ussually 3. The issue was resolved when I found that small nick in the insulation of the injector wire. It was very close to the connector, and near where the plug wire crosses over the fuel rail. The wire beneeth had a few strands cut frayed as well.

 

I can't say for sure. But since I dabbed some solder on the wire, insulated it, and moved the plug wire away from it slightly, there has been no problem, 7 months now.

 

I really think that these persistent misfire issues are from *noise* issues between the injector wires and the spark plug wires. Perhaps exagerated when wires don't fit right and run tight over the injector rails.

 

That's an intriguing theory. I will check that out. I didn't want to get way down into the injector leads, uncover a bunch of wire and try to find bad connections, but I will inspect those areas near the fuel rails and plug wires.

 

I've gotten a few weeks without a code, but never anything like 7 months. You must have found the problem on your car anyway.

[subsince77]

I think I will get the igniter from davebugs and just try it. I took a look at the injector leads and didn't see anything obvious. I do think I will snip the zip tie that is holding the one on the right side to the rail, tape the whole thing up, then re-zip tie it a bit looser so it isn't crammed against the rail. It could be worn through under there - don't know yet.

 

Thanks edrach for the offer to help, but the ignited dave has is the right one so I'll just get that one. I appreciate all the suggestions from everyone.

[edrach]

Thanks edrach for the offer to help, but the ignited dave has is the right one so I'll just get that one.

No problem, the important thing is you get it fixed.

 

Kind of late in the game but I have the electric shop manual for my '97 Impreza. I could send you a copy of the pages for the 303 and 304 codes out of the troubleshooting section. Sorry that didn't occur to me earlier in this thread.

[subsince77]

No problem, the important thing is you get it fixed.

 

Kind of late in the game but I have the electric shop manual for my '97 Impreza. I could send you a copy of the pages for the 303 and 304 codes out of the troubleshooting section. Sorry that didn't occur to me earlier in this thread.

 

That would be great. Thanks. I'll Pm an address.

 

BTW, the light came on again this morning after just a short drive, not hot at all, on a deceleration from about 50 mph. And, this is with the other ECU, so that's not it either. This one was only #4 however. I am going to go over those injector leads carefully as soon as I get some time.

[Gnuman]

That would be great. Thanks. I'll Pm an address.

 

BTW, the light came on again this morning after just a short drive, not hot at all, on a deceleration from about 50 mph. And, this is with the other ECU, so that's not it either. This one was only #4 however. I am going to go over those injector leads carefully as soon as I get some time.

 

Also pull the plug on that cyl. it could be fouled from earlier misfires (just clean it up and go). . .

[subsince77]

I just noticed something interesting this weekend, although I don't know how relevant it is. We traveled from Gunnison to Durango for a triathlon carrying two bikes on top, and running the A/C. That route takes us over two smaller passes and three big ones. The CEL came on after just a short time on the highway. I checked it and turned it off a couple of times. Same old thing #4 and #3 misfire - no indication of anything wrong except the CEL.

 

I noticed something that occurred over and over. We would cruise up a pass, that meant anywhere from 15 minutes, to 1/2 hour running along mostly in third at 3500 to 4000 rpm. At the top, as soon as I let off the gas to start down the other side, the CEL would begin to flash, and continue for as much as a minute, until I gave it some gas at a flat or slight uphill. Then it would just go back to a solid light. I've read that flashing CEL is supposed to indicate something major, but again, there is never any noise, missing, surging - nothin' but the light.

 

Does this mean anything in-particular? I would assume there would be a big difference in vacuum between uphill and downhill, but I don't know much about this.