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Ever since my wife bought her 2000 Outback Legacy, she's been having recurring p0304 code popping up. I've already changed the soak plus, so I know it can't be that, but I still haven't figured out what the problem could be. A friend mechanic told me to switch the cables from 1 & 2 to 3 & 4 to check the coil. It wouldn't start so I switched them back and the code disappeared. I'm not sure what to make of it. I was going to get a new coil, but want to make sure that it's that and not something else. Acceleration has some issues like it doesn't want to them suddenly a lot after 3500 rpms. I'm hoping it's not the fuel injector. Let me know if I'm missing something, since I'm at work trying to finish this post.
 

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2001 VDC/SC One of a Kind
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Welcome to the forum Jonathan. :grin2:

The misfire is gone altogether now?

I will assume you know the cylinder orientation?

When you swapped plug wires and it wouldn't start, I will assume they were orientated to the wrong cylinders. The coil is, from looking down on it from the front of the car, front left cyl 1, front right cyl 2, back left cyl 3, back right is 4, in line with the engine's cylinders.

I doubt its the injector. Seriously. You can look for chaffing in the harness, but injector is HIGHLY unlikely.

How old are the ignition cables?
Have you checked your battery and battery cables condition? (amperes output not volts)

For the misfires and the throttle response:

I would also suggest you clean the carbon from the throttle body. You can use throttle body cleaner and a soft bristle tooth brush to get it cleaned up good. The carbon inhibits the throttle plate movement and effects air flow. Next would be the PCV valve - probably needs cleaned.

I would also suggest a bottle of Sea Foam for your next fill up to clean any gum deposits from the injectors and decarbonize the combustion chamber. It works; trust me. Use it all the time in the tank and in a small cleaning container for when I have an engine apart and have to get in to tight spots with a brush.

These cars are easy to work on and simple things can make for issues that seem, or become, major issues. So, catch up maintenance and go from there. Let us know what transpires, please.
 

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03 H6 OBW & 06 WRX Sportwagon
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^^^^ good post

did you install NGK plugs?

did you see any oil on the plug wire boots?

19 year old plug wires may be getting tired too.
 

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Discussion Starter #4
Welcome to the forum Jonathan. <img src="http://www.subaruoutback.org/forums/images/SubaruOutback_2014/smilies/tango_face_grin.png" border="0" alt="" title="Big Grin" class="inlineimg" />

The misfire is gone altogether now?

I will assume you know the cylinder orientation?

When you swapped plug wires and it wouldn't start, I will assume they were orientated to the wrong cylinders. The coil is, from looking down on it from the front of the car, front left cyl 1, front right cyl 2, back left cyl 3, back right is 4, in line with the engine's cylinders.

I doubt its the injector. Seriously. You can look for chaffing in the harness, but injector is HIGHLY unlikely.

How old are the ignition cables?
Have you checked your battery and battery cables condition? (amperes output not volts)

For the misfires and the throttle response:

I would also suggest you clean the carbon from the throttle body. You can use throttle body cleaner and a soft bristle tooth brush to get it cleaned up good. The carbon inhibits the throttle plate movement and effects air flow. Next would be the PCV valve - probably needs cleaned.

I would also suggest a bottle of Sea Foam for your next fill up to clean any gum deposits from the injectors and decarbonize the combustion chamber. It works; trust me. Use it all the time in the tank and in a small cleaning container for when I have an engine apart and have to get in to tight spots with a brush.

These cars are easy to work on and simple things can make for issues that seem, or become, major issues. So, catch up maintenance and go from there. Let us know what transpires, please.
Yes the misfire is gone, but I haven't checked for any pending codes yet.

It seems that the ignition cables are original.

The battery is coming near the end of its life and has had corrosion/calcium build-up, and cables show no fraying.

I'm about to go clean what you suggested, and let you know how it runs after wife comes back since shell be using it today.

Also, I did buy ngk plugs. There's only slight amount of oil probably from putting in the plugs.
 

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Yes the misfire is gone, but I haven't checked for any pending codes yet.

It seems that the ignition cables are original.

The battery is coming near the end of its life and has had corrosion/calcium build-up, and cables show no fraying.

I'm about to go clean what you suggested, and let you know how it runs after wife comes back since shell be using it today.

Also, I did buy ngk plugs. There's only slight amount of oil probably from putting in the plugs.
So that's not calcium, its acid. When you get acid build up on the battery post and cable clamp it means the battery post's seal is leaking and the acid is escaping through the leak, usually as a vapor when the battery gets heated from use.

The oil is a sign that the spark plug tube seals, under the valve/cam cover, are beginning to leak. Maybe think about new valve cover seals in the near future.
 

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Discussion Starter #6
The oil is a sign that the spark plug tube seals, under the valve/cam cover, are beginning to leak. Maybe think about new valve cover seals in the near future.
Okay, I've finally been able to put in the Seafoam, and it's already running smoother. I checked the valve covers and they seem to still be in good condition. We're thinking the reason for the oil and the misfiring were from the gunk build-up in the injectors. The misfire did show up again before we put in the Seafoam and before I checked the covers. I will need to replace spark plug #4 because of the misfire, but still haven't had time.

I'd like to apologize for the late update. I've been working OT at work and haven't been able to work on the car until now. As I was saying, it runs smoother. My wife came up the mountain and said it wasn't struggling as much as it use to, but the rpm's were higher than normal by a little.
 

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It's time for another update. I've done more work on this car, and the misfire has been coming back after a few startups and driving around. I tested the coil pack and the were some doubts to whether or not it was still good so I replaced it, and it worked good for a few days, then misfired twice for my wife going somewhere then coming back home. She neglected to tell me, and then I used it the next day with a really rough startup. It shook so much I actually turned it off immediately then restarted it and was still rough, but not bad pushed on the gas to get the fuel running better and continued being normal roughness, since this problem started up, again.

After a week or two driving it myself, remember this is my wife's car, I noticed that pushing on the gas making it go up to 3000 rpm(I experimented till I found it always worked at 3000) it would run smoother and startup without a misfire as much if I did so. This meant I should look at the injectors. All of them were not faulty. I sound checked them all, and tested them with a multimeter. Then when I had free time I took them all off and saw that the connector for #4 was clogged. I cleaned it then switched where I put them. I put #4 in #1 and vice versa. #2 I put in #3 vice versa. It ran better for a day then surely enough misfire cylinder 4.

For lack of any other idea, I did something simple and got a new fuel filter, cause it was possible my wife got some bad fuel. My wife was amazed when she started the car next saying it was back to normal. This was a few days ago(a week ago) btw the others taking weeks for me to actually work on the car. But unfortunately the misfire came back shortly after. Monday it still had the same problem, but we still went down the mountain to do something with friends. The car actually overheated again which it hasn't done for a while now, but without the gauge even near red. We had to let it cool down for a while even though it was cold out and put more antifreeze in. Coming back up the mountain was fine and when we reached home no steam. The car sat for two days undisturbed and started up without any problems for the last three days. All this time the check engine light has been on. Today it turned off while driving. I'm finding this very odd. I've ordered a cable so I can use rom raider. But I'm wondering why it would remove the cel when I haven't even gone the appropriate amount of miles for it to reset. I know this is a lot to read, and I hope I'm not forgetting something and even as I type this I just remembered that I also replaced the front o2 sensor after the coil pack since he readings were bad on it. If anyone has an idea what's going on here, I'd be appreciative. There's still a chance for the misfire to happen again considering how this car's been treating me, but I hope it's at its end. I'll need to replace my passenger side axle next I noticed when changing the o2 sensor, and I don't want to spend too much more on replacing parts to deal with misfires. Thank you in advance. And thank you cardoc for your previous help.
 

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Did you ever get the battery changed and the cables fixed? Sporadic misfires are indicative of poor electrical flow. Also, have you looked in to the fuel module and checked the pressure bowl's cap and seal. You could be losing fuel pressure at the module. This would cause the high rpm cutout, which could be your misfire. How old is the timing belt. 2000 model has to have some miles on it by now unless it's been a garaged car until you bought it. Has there been any other codes pop up? Does your scan tool give you "Pending" codes? These are codes that indicate an issue prior to the drive cycle monitor completing and the ECM is waiting for a completion prior to setting the code. They are also codes that show an issue but the ECM is comparing data to verify.
 

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Discussion Starter #9
Did you ever get the battery changed and the cables fixed? Sporadic misfires are indicative of poor electrical flow. Also, have you looked in to the fuel module and checked the pressure bowl's cap and seal. You could be losing fuel pressure at the module. This would cause the high rpm cutout, which could be your misfire. How old is the timing belt. 2000 model has to have some miles on it by now unless it's been a garaged car until you bought it. Has there been any other codes pop up? Does your scan tool give you "Pending" codes? These are codes that indicate an issue prior to the drive cycle monitor completing and the ECM is waiting for a completion prior to setting the code. They are also codes that show an issue but the ECM is comparing data to verify.
I haven't actually changed out the battery yet. I did test it and it was within range. I do know it's about 5 years old, but was waiting for funds to come in. I've recently got a raise, so that's been helpful to actually buy parts I need. I'll have to check on the module on my day off. I did clean the connectors up, however.

I've recently changed the timing belt, so it's only like 1-3000 miles most likely closer to 1000.

As for any other codes, nothing else has shown up, and nothing pending. Also the cel came on again this morning after I started driving with a hiccup during startup. The hiccup lasted only for 3 seconds, and then smoothed out.

I'll have to talk to my wife about getting a new battery now since it's past warranty.

Thank you for such a speedy reply. I'll try to update Monday evening about the fuel module.
 

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I haven't actually changed out the battery yet. I did test it and it was within range. I do know it's about 5 years old, but was waiting for funds to come in. I've recently got a raise, so that's been helpful to actually buy parts I need. I'll have to check on the module on my day off. I did clean the connectors up, however.

I've recently changed the timing belt, so it's only like 1-3000 miles most likely closer to 1000.

As for any other codes, nothing else has shown up, and nothing pending. Also the cel came on again this morning after I started driving with a hiccup during startup. The hiccup lasted only for 3 seconds, and then smoothed out.

I'll have to talk to my wife about getting a new battery now since it's past warranty.

Thank you for such a speedy reply. I'll try to update Monday evening about the fuel module.

by timing belt: do you mean just the rubber belt, or a timing belt kit. (components get old and seize up and break brand new belts).
 

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Just the rubber belt, not the kit. I only did the belt because I could see it wearing a bit, and didn't think anything about the whole kit.
 

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I've seen valve guides drop and cause a re occurring issue like this. If you run out of parts to throw at it, drop your exhaust and inspect, it'll be noticeable if they did drop.
 
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I tried getting the fuel regulator yesterday, but ran into a problem. The screws have seen too many days and when trying to loosen the bottom one it stripped too much for me to remove it. If there's anything wrong with it I'll have to buy a new fuel rail along with it.

Strange thing however, cel was still on Sunday, but when I started it on Monday morning for work it turned off yet again. It started normally with the usual high rpms(1500), but no roughness or any sign of missing. I only did a half day at work, so I came home and worked on it. After much struggling with it I put it back together and started the car. No check engine, no roughness with high rpms, but the rpms dropped steadily going down to 800 rpms within a couple minutes. Turned it off then restarted in 4 seconds and started with 1200 rpms and settled faster this time. Once again started after 5 seconds this time 1000 rpms and settled within a few seconds. This morning it started fine both times.
 

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I've seen valve guides drop and cause a re occurring issue like this. If you run out of parts to throw at it, drop your exhaust and inspect, it'll be noticeable if they did drop.
I didn't even notice this post till after posting, sorry for that. I have seen the same issue as well, but when looking at how those engines were working I'm doubting it... and hoping. From my understanding, when that happens, if the car is going at higher rpms, it would be noticeable. I've gone on highway speeds, both at close sea level and going up a mountain 1 mile high, and never noticed any knocking or sputtering or even rough running. I'm saving the valve drop issue for last for this very reason.

This problem seems more of an afr issue, so I'm focusing more on that. I was going to check the fuel pump yesterday as well, but I found out last minute that I had to go to work yesterday, and ran out of time due to previous post problem.
 

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New development, we had to go somewhere else today and cel didn't come on and the only light that lingered was at oil temp. Coming back home I was watching the dash and the cel never came on, so I suspect the same before. I haven't checked the lightbulb yet seeing as it happened a minute ago, but my concern is if it's possible the ecm is failing.
 

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Go back to the battery and grounding. I doubt the ECM is the problem. You will get problems from the ECM if the available current from the battery and alternator are low. I've had plenty of cars that all the maintenance is up to date and exhibited problems due to low battery/alternator output that were corrected with replacement and/or add on grounds.

Along with the video of an LL Bean exhibiting multiple misfires, another Honda/Isuzu with multiple AF codes and transmission codes, I had a customer that had a Civic that had an alarm system that reported "low voltage" to the monitoring company twice. After the second report the alarm company notified the owner. He got quotes for an alternator from 3 shops, all over $700, then came to me where I found a bad ground cable running from the battery to the block. I manufactured the cable and cleaned the others and everything is back to working tip top. I could give you more but I have plenty of post on this forum showing how grounds, battery and alternator function are the first go to with multiple or intermittent issues. Wouldn't want you to fork out money on an ECM to find out it doesn't solve the problem. Start with the battery. You already know its leaking by the acid build up at the post.
 

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Go back to the battery and grounding. I doubt the ECM is the problem. You will get problems from the ECM if the available current from the battery and alternator are low. I've had plenty of cars that all the maintenance is up to date and exhibited problems due to low battery/alternator output that were corrected with replacement and/or add on grounds.

Along with the video of an LL Bean exhibiting multiple misfires, another Honda/Isuzu with multiple AF codes and transmission codes, I had a customer that had a Civic that had an alarm system that reported "low voltage" to the monitoring company twice. After the second report the alarm company notified the owner. He got quotes for an alternator from 3 shops, all over $700, then came to me where I found a bad ground cable running from the battery to the block. I manufactured the cable and cleaned the others and everything is back to working tip top. I could give you more but I have plenty of post on this forum showing how grounds, battery and alternator function are the first go to with multiple or intermittent issues. Wouldn't want you to fork out money on an ECM to find out it doesn't solve the problem. Start with the battery. You already know its leaking by the acid build up at the post.
I hadn't checked the light though, which it turned out to be. The obd2 reader showed the misfire still in the computer. I'm trying to convince my wife to switch out the battery. The problem hangs on the fact that we're looking to replace the outback for another car considering it's on its last legs, and our family is growing.
Number three will be here by new year's. She doesn't want to spend too much more on it since we'll take it to the scrapyard after we find a new car instead of selling it. I personally don't feel comfortable selling it to someone else, because of neglect from the previous owner. I could finish fixing all the problems it has, but it's a 2000 with 200k miles right now. If it was in perfect condition, it wouldn't sell more than 1500 anyways. We're still waiting on the cable to come in so I can check readings on rom raider as well. I think this would convince her to at least to get a new battery. When we've saved up enough I may suggest the axle again, but we definitely need new brake pads soon using it to do appointments down the hill.

Thank you for efforts. I'll check more of your posts about electrical components. I completely understand how many problems there are around that need solving and are more pressing.
 

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I had the battery tested at the parts store and it was at a staggering 350cca, so we will hopefully get a new battery on Tuesday. I also finally got the cable in to use romraider, and have everything setup but I was wondering which parameters to log to help determine what is causing the misfire just in case that battery doesn't help. I've logged once already with everything selected, but they don't suggest that. Things I've noted: key in on position 11.9v; startup drops to 9.6v; idle 13.84, but fluctuates; manifold absolute pressure 3.77; relative -8.13; corrected -8.13; throttle opening angle only goes up to .89 even with pedal all the way down.

I'll post the actual log after narrowing down which ones to select so it's easier to read. The one I have was first attempt so is very long, and I can't remember everything I did. Total time missing with it was 20 minutes, and with driving as well.
 

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I had the battery tested at the parts store and it was at a staggering 350cca, so we will hopefully get a new battery on Tuesday. I also finally got the cable in to use romraider, and have everything setup but I was wondering which parameters to log to help determine what is causing the misfire just in case that battery doesn't help. I've logged once already with everything selected, but they don't suggest that. Things I've noted: key in on position 11.9v; startup drops to 9.6v; idle 13.84, but fluctuates; manifold absolute pressure 3.77; relative -8.13; corrected -8.13; throttle opening angle only goes up to .89 even with pedal all the way down.

I'll post the actual log after narrowing down which ones to select so it's easier to read. The one I have was first attempt so is very long, and I can't remember everything I did. Total time missing with it was 20 minutes, and with driving as well.
on a 2000 there are not that many available parameters, vs. 2006 and up.

keep the log to 1-2 minutes when the problem is occurring.

rom-raider has a toggle for the rear defroster to start a log. so you can hit it with a button on the dash as opposed to opening and clicking on a laptop while you maybe driving. (see it in the menus at the top of the screen).

but any electrical testing starts with a known good battery and hopefully good battery cables.:smile2:
 

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We got the new battery, and working good so far. I hooked it up to rom raider and noticed a difference in the readings. Almost everything was off slightly. I'm not sure if it'll misfire again, but we'll find out eventually.
 
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