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95 Legacy intermittently runs rough


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One of the reasons you're looking for answers here is experience.

 

And experience has told you OEM(Subaru).

OK I hear you guys. I guess the question for me is "do I feel lucky"?:)

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Ouch that hurts!! I just paid $74 with tax. But I need the car for a gig tomorrow night, so I don't have time for mail order.

 

Actually the car has been running OK all this morning as I went around exchanging parts & buying more stuff. Go figure. I'm sure it could use the new parts anyway (if not more stuff).

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You may well be right, crash. Would fuel injector cleaner or Techron concentrate help with that?

 

The only thing I have found that helps with a sticky regulator is Lucas fuel injector lube. Fuel injector cleaner and techron don't have a lube quality to it. The lucas should help but it won't fix it. It is just a band aid till you can get it fixed. The only way to make sure it is the regulator though is to put gauges on it. But thos symptoms are classic regulator going south. my .02:)

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The only thing I have found that helps with a sticky regulator is Lucas fuel injector lube. Fuel injector cleaner and techron don't have a lube quality to it. The lucas should help but it won't fix it. It is just a band aid till you can get it fixed. The only way to make sure it is the regulator though is to put gauges on it. But thos symptoms are classic regulator going south. my .02:)
I just posted on my other "spark plug change" thread, now I have two threads going, sorry! Maybe I should keep everything over here.

 

I'm curious -- when you say these are "classic" symptoms, do you mean the fact that this rough running happens only intermittently? What exactly are the "classic" symptoms of a sticky regulator?

 

And assuming this is the problem, how much of a deal is it to fix? Is this part easily accessible or should I be scheduling an appointment at my local garage? Thanks much for your help!!

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I'm curious -- when you say these are "classic" symptoms, do you mean the fact that this rough running happens only intermittently?

 

Yes

 

What exactly are the "classic" symptoms of a sticky regulator?

 

 

Also, no one has mentions the possiblity of a fuel pressure regulator that may be going bad which could be causing these issues, too much fuel can foul an EGR, cause the O2 sensor to fail creating the cat code and cause a misfire on a weak cylinder. Does your exhuast smell rich? Don't just throw parts at it.:-\

 

And I would throw in there that it will come and go but you will always notice it at idle. The mechanism in the regulator is getting sticky and won't adjust the fuel pressure accordingly. So when you are coming off throttle and you come to a stop, you do not need as much fuel to run that engine. The regulator is suppose to reduce that pressure so that your injectors are not supplied with too much fuel. That is the chugging you are experiencing intermittantly.

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And I would throw in there that it will come and go but you will always notice it at idle. The mechanism in the regulator is getting sticky and won't adjust the fuel pressure accordingly. So when you are coming off throttle and you come to a stop, you do not need as much fuel to run that engine. The regulator is suppose to reduce that pressure so that your injectors are not supplied with too much fuel. That is the chugging you are experiencing intermittantly.
Well maybe it isn't this regulator after all. My car idles normally. The rough running seems to happen only while I'm moving. At least that's what I'm noticing so far.

 

Tonight on my way home I had another small episode of momentary rough running & loss of power. It lasted about 5 seconds. Tomorrow night I have a long drive to do, very late at night, on back roads -- not sure if there's even cell reception. So I am a little concerned.

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I looked at the codes the car threw-

First if cylinder 3 has a misfire, it is likely cause in the catalytic converter below threshold code- and bank 1 means the front cat, and bank 2 is the rear cat. converter- this is standard for all OBD II vehicles- almost never truly refers to the cylinders (don't believe anything Autozone or Advance Auto tells you they don't know anything- I have been working on cars for 17 years and have all but my tranny ASE cetifications so I know what the code really mean). Also cat converter really don't go bad that often- takes physical damage or severe loading with fuel to melt them down (unless some one was using additives in the fuel that are not sensor safe - can coat cat too but this is no common anymore - more of a 1980's problem) O2 sensors which the computer relies on to check the cat do go bad- pretty cheap and easy to fix ($100 or under versus $500+ for a cat). Don't let a misfire go too long - this is the most common reason for catalytic converter failure because the leftover fuel goes in the converter and melts it down (overheats converter). I have seen dealers get out of warranty on converters because people left a misfire go for a long time on a vehicle and then could not pass emissions due to a converter code and the misfire- the misfire destroyed the converter- that's not covered under the federally required warranty on converter.

The code that could be causing more of the running and overheat issue (and can cause misfire) is the EGR code- EGR could be getting stuck open (stuck shut doesn't cause the same noticeable driveability problem- just codes and these valves default to a normally closed position unless stuck), allow too much very hot exhaust gases back in the cylinders- not enough fresh air for fuel to burn correctly= misfire and cat. codes, plus exhaust gases are hotter and will cause the temp to rise=overheat or long fan run at idle. To check the valve if it is stuck, make sure the car is cold, put your finger in where the diaphragm is and press the pin in- if it doesn't move it most likely has carbon stuck in it You may be able to remove the valve (use a flare wench for the pipe fitting to prevent stripping it- not sure of size but I am guessing 17mm most likely) and clean the valve and check in the pipe for carbon (if you can get the pipe off- not easy and a PITA to get back on-clean it out too). EGR valve commonly get carbon in them - especially if ran around town a lot then taken out on the highway and ran fast. A chunk of carbon can break off and jamb the valve open.

You can clean them with intake cleaner - set the valve so you can fill it with the cleaner and let it sit for a while, then work the pin for the valve in and out - if it won't move, these's carbon stuck in it that didn't dissolve. Dump out the cleaner, and use a rubber mallet to hit the valve on the body- not really hard- just enough to jar the carbon loose (more hits are better that really hard hit at loosening it up- but don't be too afraid). Then turn the valve over and try to shake out the carbon piece- once it is out, fill with cleaner again, let sit, empty and let dry totally (takes about 1 hr. for cleaner to evaporate - make sure you shake out as much cleaner as possible). Reinstall using new vacuum line to it and the back pressure transducer (the black plastic valve immediately in front of the EGR - it controls the EGR but not common for going bad- vacuum lines do go bad). Run the vehicle for a few days- clear the codes first by disconnecting the battery for 5 minutes - if it still is having an issue with the EGR code you may need to replace the valve - bad diaphragm. I don't know if you would want to jump to a parts replacement right away- valves can be pricey (about $200 from NAPA) and the cleaning takes time but is cheap ($20 for a flare wrench and $10 for cleaner and vacuum hose). Hope this helps.

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ryverrat, I can't thank you enough for the mountain of information you've given me. I printed it out & will be referring to it in the next week, as I try and fix this car. It's really all my fault as I neglected to do almost all the regular maintenance except oil & filter changes. The car just ran great and I got complacent.

 

The check engine light has been on for a while, so I'm a little concerned the misfiring may have been going on long enough to damage the cat, although I can honestly say that I never detected anything wrong with how the car was running (until it started running rough in the last week, of course). After a while I assumed it was a bad sensor causing the light. If I'm lucky, it'll turn out to be one of the other codes, not the misfire, that got turned the light on. I have to say that one of the old spark plugs looked noticeably different from the other three so I guess there was something going on in one of the cylinders.

 

I was tentatively planning on replacing the front o2 sensor next, however I will first check the EGR valve to see if it's stuck as you suggest. I've been driving around town the last few days and about 98% of the time it does fine. Once in a while the rough running & loss of power kicks in and lasts for 5 seconds to a minute or so. One thing I notice is that when I first start the car the exhaust is smoky (but not dark, like oil burning, and no coolant smell -- just smoky). I have seen a small amount of water at the end of the tailpipe too. After I drive the car a while, I stop & idle the engine, then check the tailpipe- no smoke, no moisture. Not sure if this is normal or not.

 

Again, I really appreciate the detailed explanation of my codes and your tips on cleaning the EGR valve. That is one fairly expensive piece and I'm not sure I have the skill to replace it myself. Thanks!!

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