Numbchux Posted June 13, 2008 Share Posted June 13, 2008 '96 Legacy Outback Wagon, 4EAT, DOHC EJ25D, 126k miles. mysterious rough-running, stumbling, etc. only while under load (not necessarily driving, but never does it in park or neutral). noticeably aggravated by the A/C compressor (symptoms come and go as the compressor cycles on and off), although sometimes the symptoms appear independent of the A/C. occasionally the CEL will flash for a minute (indicating misfire....), plug in the code reader, and it's always cyl. 2. quick visual inspection of the engine bay doesn't reveal any noticeable problems. Thoughts?! Link to comment Share on other sites More sharing options...
idosubaru Posted June 13, 2008 Share Posted June 13, 2008 plugs, wires...when were they changed and what brand are they? EJ engines are notorious for having ignition issues, they are not nearly as forgiving as older generation engines. that being said the usual solution are new plugs and wires. the second solution is to make sure they are OEM plugs and OEM (or magnecor) wires. i've seen brand new and relatively new wires cause issues....best to stick with OEM Subaru on EJ engines. if that's not it you can swap in another coil. swapping plug wires and plugs can help determine the cause. if the problem moves with the plugs or wire then that's the culprit. Link to comment Share on other sites More sharing options...
Numbchux Posted June 13, 2008 Author Share Posted June 13, 2008 unknown history on both. but, being DOHC, replacing them isn't a small job....so I wanted to be sure. And, my EJ22e had some pretty nasty plugs and wires on it, and I noticed exactly zero difference when switching from fouled autolites to NGKs.... Link to comment Share on other sites More sharing options...
OB99W Posted June 13, 2008 Share Posted June 13, 2008 Several things can cause misfire. Running the A/C adds a load to the engine, which can aggrevate problems. Ignition issues are certainly one possibility. So are fuel delivery (injector) problems. Then there's valves... Since you seem reluctant to replace plugs and wires, at least verify that the wires are making good contact at the coil pack. If you do pull plugs, be sure to check compression while they're out. You could try swapping injectors between cylinders, and see if the problem moves. Here's some info on removing and reinstalling them: http://endwrench.com/images/pdfs/ProperInsideEWFall05.pdf Do you have access to a scan tool that can read "live" data (specifically short and long term fuel trims)? If so, it's possible to check injector balance without pulling them. Link to comment Share on other sites More sharing options...
Cougar Posted June 13, 2008 Share Posted June 13, 2008 Some folks have had success clearing a misfire by running some Seafoam through the one of the vacuum lines while revving the engine. It helps clean the carbon out of the cylinders. Link to comment Share on other sites More sharing options...
idosubaru Posted June 13, 2008 Share Posted June 13, 2008 i wonder if testing of the ignition coil procedures are on here or you have an FSM to look for that? that should be an easy test to do. chances are very high that it's plug wire related. if it's running bad, try popping the hood in a very dark place and watching for sparks with the engine idling. have someone give it gas and keep an eye out. i think some people have recommended light spritzing of water to exacerrbate the sparks but i've never done that myself. #1 and #2 plugs and wires, is that too much work? those 90 degree holes are annoying for sure. grab another spark plug wire and swap it with the cylinder #2 wire, otherwise i can't think of a specific way of positively identifying the cause. if the plugs/wires are of uknown age/mileage i'd personally want them/recommend them be replaced anyway but i can understand that's not the best fit for everyone. Link to comment Share on other sites More sharing options...
Gloyale Posted June 13, 2008 Share Posted June 13, 2008 I had a 2000 Outback SOHC 2.5 recently with a chronic #3 misfire. I believe I traced the problem to a slice in the insulation, and a couple(literally 2) of the strands of the #3 injector signal(-) wire, very near the clip. After removing the pin from the connector, I carefully stripped insultation off the frayed area. Then applied a small dab of solder on the split wires. Then heat shrink wrapped the wire. Reinserted into the clip and reinstalled. Car has not had said misfire for almost a month. Noting yet conclusive but just a recent experience. Link to comment Share on other sites More sharing options...
OB99W Posted June 14, 2008 Share Posted June 14, 2008 I had a 2000 Outback SOHC 2.5 recently with a chronic #3 misfire. I believe I traced the problem to a slice in the insulation, and a couple(literally 2) of the strands of the #3 injector signal(-) wire, very near the clip.[...] Car has not had said misfire for almost a month. Noting yet conclusive but just a recent experience. It's certainly possible. Injectors have relatively low impedance, and need to turn on rapidly. Excessive resistance due to some cut conductors could affect the response. Link to comment Share on other sites More sharing options...
Numbchux Posted June 14, 2008 Author Share Posted June 14, 2008 today I swapped #2 and #4 plug wires. and pumped some SeaFoam through it. with zero change. I bought some new NGK plugs, and have another coil and igniter (although I'm hesitant to suspect either, as I bet the wasted spark design would cause a misfire on #4 as well) to try tomorrow. I will also try to get my hands on a compression tester while I'm in there (god I hope it's not a burnt valve ). Link to comment Share on other sites More sharing options...
98obster Posted June 14, 2008 Share Posted June 14, 2008 PCV valve? just a thought-easy enough to inspect. experiencing any mystery oil comsumption? Link to comment Share on other sites More sharing options...
OB99W Posted June 14, 2008 Share Posted June 14, 2008 [...]I bought some new NGK plugs, and have another coil and igniter (although I'm hesitant to suspect either, as I bet the wasted spark design would cause a misfire on #4 as well) to try tomorrow.I mostly agree. The only way a bad coil pack could cause just #2 (and not #4) to misfire would be if that secondary coil was leaking to ground near the #2 end. I can't see it being the igniter either, based on wasted spark. A bad plug, on the other hand, could affect just one cylinder. I will also try to get my hands on a compression tester while I'm in there (god I hope it's not a burnt valve ).Yes, and if compression is okay, you can cross "burnt valve" off the list; if it isn't, you can stop wasting time and money on other possibilities. You may not always like the outcome, but diagnosis is usually better than throwing parts at a problem. Link to comment Share on other sites More sharing options...
Gloyale Posted June 14, 2008 Share Posted June 14, 2008 It's certainly possible. Injectors have relatively low impedance, and need to turn on rapidly. Excessive resistance due to some cut conductors could affect the response. The injector harness and the spark plug wires run very close to eachother. That is where the cut was. I think somehow being uninsulated near the plug wire was causeing *noise* on the wire. Link to comment Share on other sites More sharing options...
Numbchux Posted June 14, 2008 Author Share Posted June 14, 2008 did a compression test and new plugs today. compression checked out at 190psi (+/- 5) on all 4 on a cold motor, so not a burned valve. it had champion plugs in $1,2 & 3. and a nasty NGK in #4. seems to be fixed..... Link to comment Share on other sites More sharing options...
idosubaru Posted June 14, 2008 Share Posted June 14, 2008 it had champion plugs in $1,2 & 3. and a nasty NGK in #4. seems to be fixed.....not surprised. i know other things can cause it but in my experience it has been plugs/wires 100% of the time. i've even seen brand new and fairly new spark plug wires cause cylinder misfire issues and driveability issues on EJ engines. i've never seen that happen with older EA/ER stuff. very common. Link to comment Share on other sites More sharing options...
Hendrik Posted June 14, 2008 Share Posted June 14, 2008 '96 Legacy Outback Wagon, 4EAT, DOHC EJ25D, 126k miles. mysterious rough-running, stumbling, etc. only while under load (not necessarily driving, but never does it in park or neutral). noticeably aggravated by the A/C compressor (symptoms come and go as the compressor cycles on and off), although sometimes the symptoms appear independent of the A/C. occasionally the CEL will flash for a minute (indicating misfire....), plug in the code reader, and it's always cyl. 2. quick visual inspection of the engine bay doesn't reveal any noticeable problems. Thoughts?! Not your engine type (mine= EJ18), but similar "uncertain" behaveour , changed the plug wires (a bit outside spec) , new plugs , O2 sensor , no change. Now I know it was an injector , seems to happen seldom , so I also was replacing anything else. Link to comment Share on other sites More sharing options...
OB99W Posted June 14, 2008 Share Posted June 14, 2008 The injector harness and the spark plug wires run very close to eachother. That is where the cut was. I think somehow being uninsulated near the plug wire was causeing *noise* on the wire.Insulation, or the lack of it, doesn't affect inductive cross-coupling, which is what you're describing. All other things being equal, it's dependent on the distance between the two conductors, the energy level, and the relative impedance of the circuits. However, there could have been more noise induced, as you suggested. An increase in wiring resistance due to cut conductors, in addition to slowing injector pulse rise time, could also make cross-coupling to the injector more likely. Whatever the mechanism, you made a good point that damaged wiring could lead to misfire. Link to comment Share on other sites More sharing options...
idosubaru Posted June 15, 2008 Share Posted June 15, 2008 seems to be fixed..... woo hoo! did the old plugs look bad? wonder why there were two different kinds? Link to comment Share on other sites More sharing options...
OB99W Posted June 15, 2008 Share Posted June 15, 2008 did a compression test and new plugs today. compression checked out at 190psi (+/- 5) on all 4 on a cold motor, so not a burned valve. it had champion plugs in $1,2 & 3. and a nasty NGK in #4. seems to be fixed.....From the compression readings, it certainly seems like the engine is basically healthy. Not that an NGK can't be bad (or just too well-used), but I've seen more problems with Champions. It's interesting that even the "nasty" NGK on #4 worked better than its Champion wasted-spark-mate on #2. By the way, could you ID the Champion plug model? [...]wonder why there were two different kinds?It wouldn't surprise me if the NGK was an original, and whoever put in the Champions found replacing #4 to be too much of a challenge. Or perhaps a Champion was installed in #4, failed early, and a used NGK was put back in. Link to comment Share on other sites More sharing options...
Numbchux Posted June 16, 2008 Author Share Posted June 16, 2008 From the compression readings, it certainly seems like the engine is basically healthy. Not that an NGK can't be bad (or just too well-used), but I've seen more problems with Champions. It's interesting that even the "nasty" NGK on #4 worked better than its Champion wasted-spark-mate on #2. By the way, could you ID the Champion plug model? #2 and 1 share the same coil. 2 and 4 are on different coils. but none the less, the NGK was definitely in the worst condition, and was still running better than the champion. #2 was definitely in the worst condition of the champions though. I didn't look at the old plugs. but I'll take a peek (they're in the boxes waiting to be thrown out...) and see if I can tell. It wouldn't surprise me if the NGK was an original, and whoever put in the Champions found replacing #4 to be too much of a challenge. Or perhaps a Champion was installed in #4, failed early, and a used NGK was put back in. it sure looked like the NGK had 130k miles on it....definitely could have been factory (yikes!). so I was thinking one of those 2 scenarios, probably the former. Link to comment Share on other sites More sharing options...
OB99W Posted June 16, 2008 Share Posted June 16, 2008 #2 and 1 share the same coil. 2 and 4 are on different coils. but none the less, the NGK was definitely in the worst condition, and was still running better than the champion. [...]Ooops, I do (usually!) know which cylinders are paired in the wasted spark arrangement; #3 would of course be the mate to #4. That's what I get for posting at 2:19 AM when my brain is apparently half asleep. it sure looked like the NGK had 130k miles on it....definitely could have been factory (yikes!). so I was thinking one of those 2 scenarios, probably the former.That's precisely why NGKs are preferred -- they seem to still work reliably long after other brands fail, often even when pushed well beyond the recommended replacement interval. Link to comment Share on other sites More sharing options...
Numbchux Posted June 17, 2008 Author Share Posted June 17, 2008 Ooops, I do (usually!) know which cylinders are paired in the wasted spark arrangement; #3 would of course be the mate to #4. That's what I get for posting at 2:19 AM when my brain is apparently half asleep. it's alright. when the code reader said the misfire was on cyl. 2, I had to crack open the Haynes manual to figure out which one that was. 1 & 4 I can remember, but not 2 & 3. Link to comment Share on other sites More sharing options...
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