Mikevan10 Posted July 8, 2008 Share Posted July 8, 2008 1997 Legacy, 2.2 liter, 5-speed manual, non-turbo, 198,000 miles Wife was driving car about a week ago and it began to sputter. Pulled off road. Sputtered more and stalled. Started back up but still sputtered. She called me up. Fuel was low although should not have been empty according to fuel gage or miles on that tank of gas. Still, the symptoms sounded like low fuel so I met her with a can of gas. Poured about 2 or 3 gallons in. Engine started fine and she drove it ALMOST all the way home (about 5 or 6 miles) and it sputtered again as she approached our driveway. Throughout all of this the MIL (aka CEL) never illuminated. Next day engine started fine. Filled tank. Drove car to town and back (about 30 miles) without any incident. Seemed perfectly fine. Couple of days later, started car without any indication of trouble but within a couple miles it started sputtering and stalled. She was able to re-start and limp home with engine sputtering. She was slipping the clutch to keep it going. After she got home I went out and started it up. MIL came on and stayed on as I idled (sputtered) it for a minute or so and then I shut the engine down. I went under the hood to listen for vacuum leaks, etc. Wife started car and although it was sputtering the MIL did NOT come back on. I did not hear anything unusual in the engine compartment so we shut it down to attend to other business. That was this past Sunday. Yesterday I bought a new (Wix) fuel filter and installed it. When I removed the old one (I had never changed it, and I’ve owned this car for about 6 years) I blew though it and easily pushed fuel out the other pipe. Darn it! I was hoping it would be obviously clogged. Anyway, with the new filter in the engine started up no problem and idled normally. I drove around for about 10 miles and varied engine speed and load and did not notice any problem. Seems ok now but I have zero confidence since it fooled me once already (read above). MIL remains extinguished, by the way. Please comment! Thanks, Mike V. Link to comment Share on other sites More sharing options...
McDave Posted July 8, 2008 Share Posted July 8, 2008 It sounds like a dirty Mass Airflow Sensor to me. CRC makes a spray MAF cleaner. Their Electric Contact Cleaner works just as well if you can't find the other. Just remove the MAF and spray it down good from both directions. It will air dry quickly. Take care to not actually touch the thin wires with the nozzle tip. Go ahead and pick up a new air filter at the parts store if it's about due too. That should keep it clean. If you have a chance to get the codes read it wouldn't hurt. The code will still be in memory even if the MIL light is off. I expect you will have a code for a lean O2 sensor if the MAF was truly at fault. Link to comment Share on other sites More sharing options...
nipper Posted July 8, 2008 Share Posted July 8, 2008 COuld have been a bad tank of gas..... indigestion. When was the last time the car had a tune up? Can you get a fuel pressure gauge on the car? nipper Link to comment Share on other sites More sharing options...
Mikevan10 Posted July 8, 2008 Author Share Posted July 8, 2008 Thanks for the comments, fellows. I will look for a can of MAF sensor cleaner. Any risk in doing this (like is there something about Subaru’s MAFs that they are damaged by generic MAF cleaners?)? Nipper – I guess it always could have been some “bad” fuel but it has now malfunctioned on two different tanks of fuel. And, as far as a “tune up”goes, I guess I gave it away by mentioning that I had not changed the fuel filter in many years, huh. Well, truth be told, it has not been “tuned up” in years either. But then again, what does a tune up consist of on these vehicles? I would guess new spark plugs, new spark plug wires, fuel and air filters, pcv valve? I am not sure why any of these would cause such an intermittent problem. Thanks again! Mike V. Link to comment Share on other sites More sharing options...
McDave Posted July 8, 2008 Share Posted July 8, 2008 Thanks for the comments, fellows. I will look for a can of MAF sensor cleaner. Any risk in doing this (like is there something about Subaru’s MAFs that they are damaged by generic MAF cleaners?)? Just don't use carb or throttle body cleaner as it's too harsh. Some manufacturers (GM) say you can even use spray Brake Kleen since it won't leave a residue either. But then again, what does a tune up consist of on these vehicles? I would guess new spark plugs, new spark plug wires, fuel and air filters, pcv valve? I am not sure why any of these would cause such an intermittent problem. Mike V. A dirty air filter surely will cause your symptoms as it only takes a bit of dust to cause a MAF to malfunction, and they do act up intermittently when dirty. You might want to pump a pint of gas into a clean coffee can to see if there's any water in it. Good luck! Link to comment Share on other sites More sharing options...
nipper Posted July 8, 2008 Share Posted July 8, 2008 Thanks for the comments, fellows. I will look for a can of MAF sensor cleaner. Any risk in doing this (like is there something about Subaru’s MAFs that they are damaged by generic MAF cleaners?)? Nipper – I guess it always could have been some “bad” fuel but it has now malfunctioned on two different tanks of fuel. And, as far as a “tune up”goes, I guess I gave it away by mentioning that I had not changed the fuel filter in many years, huh. Well, truth be told, it has not been “tuned up” in years either. But then again, what does a tune up consist of on these vehicles? I would guess new spark plugs, new spark plug wires, fuel and air filters, pcv valve? I am not sure why any of these would cause such an intermittent problem. Thanks again! Mike V. Fouled plugs, weak wires, and a poor fuel mix due to malfunctioing maf or a clooged filter, they can all be connected. Upi need air spark and fuel to make the car go, of course they can all be connected, because without one the others dont work. nipper Link to comment Share on other sites More sharing options...
Mikevan10 Posted July 8, 2008 Author Share Posted July 8, 2008 Understood, Nipper. My question really was really about the INTERMITTANT nature of the problem. It comes and goes completely and it seems to be more severe than just one cylinder coming and going. Regardless, I don't want to beat this to death (yet). I will try to pick up an air filter and some CRC MAF sensor cleaner tonight. I will also look into hooking up a fuel pressure gage. Thanks as always. Mike V. Link to comment Share on other sites More sharing options...
OB99W Posted July 8, 2008 Share Posted July 8, 2008 [...]It comes and goes completely and it seems to be more severe than just one cylinder coming and going. [...] It may well be more than one cylinder acting up, but of course not necessarily all four -- two would be plenty on a four cylinder engine. Getting the code(s) read could be helpful. (Typically AutoZone or Advance will do it for free.) Try to get the actual code(s) (Pxxxx), not just the code definition(s). Misfire codes are likely (P030x), but there may certainly be others. If cylinder pairs are having problems, knowing whether it's happening to a bank (#1 or #2) versus wasted spark pairs (#1 or #3) could help separate ignition from other problems. Naturally, if all four cylinders are throwing codes, that info could also be useful. When the MIL/CEL came on, was it steady, or did it flash? Were conditions warmer or wetter than usual when the problem occured? A general comment -- There seem to be more complaints of this type lately. Some people are blaming the gas supply, saying that under recent circumstances sources are less reliable and gas is of poorer quality. Even if true, I don't tend to believe that's a significant factor; rather, I suspect that due to the cost of filling up, some owners are allowing their gas tanks to get lower than usual. That can result in more condensation in the gas tank and pick-up of water and "crud" near the bottom of a tank. Link to comment Share on other sites More sharing options...
Mikevan10 Posted July 9, 2008 Author Share Posted July 9, 2008 Thanks for chiming in OB99. For the very brief period when the MIL was on, it was on steady (NOT flashing). Environmental conditions were not remarkable during any of the sputtering/stalling incidents. I do not yet have a scanner so I drove down to Auotozone last evening. The guy there told me that they only have a Cheapo scanner and it will not display any trouble codes if the MIL is not illuminated. I asked him if he could get the stored trouble codes (i.e. history) and he said No. I know a guy who has a nice scanner but he is out of town til next week. I drove the car about 25 or 30 miles last night under varying conditions. Car was also shut down and restarted several times over differing time intervals. Never had one hint of a problem. I’d like to re-emphasize that this is a definite “present versus not present” problem. It is NOT a case of the car “seeming” to be running a bit rough now and then. When it sputtered, it was clearly sputtering/stalling. I also did pick up a new air filter and a can of CRC MAF sensor cleaner last night. I did not have the opportunity to use either of them yet. I am planning to drive this car to Long Island and back this Sunday. A round trip of about 200 miles. I wish I could have some confidence in it! Again, thanks much for all your input! Mike V. Link to comment Share on other sites More sharing options...
McDave Posted July 9, 2008 Share Posted July 9, 2008 Thanks for the update. I still feel confident about my original suggestions. The thing about a dirty maf is the crud could have burned itself off and the problem may not reoccur for some time. Plugs, wires, coil, fuel pressure, water in the gas... any of those likely would have caused it to act up again on your 25 - 30 mile drive. Cleaning the maf and changing the air filter should do the trick. Just try to get in plenty of miles after cleaning and before the trip to build confidence. PS If it does act up again before the trip, get the codes read by a real garage... someone that can give a proper diagnosis. Link to comment Share on other sites More sharing options...
McDave Posted July 9, 2008 Share Posted July 9, 2008 I've done some more research on this and a maf failure is pretty common. If it gets to the point it acts up consistently, try unplugging the maf and see if it smooths out. If it does, replace maf. Link to comment Share on other sites More sharing options...
nipper Posted July 9, 2008 Share Posted July 9, 2008 WTF? It sounds like autozone just did not want to it. I have seen scanners that will only pull the codes for the illuminated CEL, and nothing more, not the other way around. Or they just do not know how to use thier scanner. Its sort of like having an xray machine that wont pick up broken bones. nipper Link to comment Share on other sites More sharing options...
McDave Posted July 9, 2008 Share Posted July 9, 2008 WTF? It sounds like autozone just did not want to it. I have seen scanners that will only pull the codes for the illuminated CEL, and nothing more, not the other way around. Or they just do not know how to use thier scanner. Its sort of like having an xray machine that wont pick up broken bones. nipper That's what Mike was saying. His light isn't lit now so this is what Autozone told him... "The guy there told me that they only have a Cheapo scanner and it will not display any trouble codes if the MIL is not illuminated." Link to comment Share on other sites More sharing options...
Mikevan10 Posted July 9, 2008 Author Share Posted July 9, 2008 Right, like Dave said, since the light is NOT on, their scanner will not display any codes. Interesting. The engine will run with the MAF sensor unplugged? Mike V. Link to comment Share on other sites More sharing options...
ferret Posted July 9, 2008 Share Posted July 9, 2008 I saw this on newer 99 and up Subaru's. They act like a bad tank of gas AFTER warmup. Some 1/2 hr, others 2 or 3 hrs later. Front Oxygen sensor was the culprit. It acted as if it was always RICH after warmup. Easy way to test, but this WILL set a code. When it is acting up, shut off the engine and unplug the front 02 sensor. The MIL will be on, but you will run in 'open loop' mode. A preset value for mixture based on engine RPM and LOAD. If the engine now runs fine, the 02 sensor is your culprit. First one of these I saw, was a few yrs back. Outback was bucking so badly, then quit. Car was flatbedded to dealer, only to start fine. Next day, same thing. But not it just would NOT start or keep running, Just like a dirty MAF, but dirty MAF's are not so intermittent. This would ALWAYS happen after warmup. Never cold. Since then, I've seen 3 more, and suggested this to many others on various Subaru Boards. P.S. My father's Day present was a trip to the Iron Pigs..... and the Bucket Hat giveaway that day !! Link to comment Share on other sites More sharing options...
Mikevan10 Posted July 9, 2008 Author Share Posted July 9, 2008 Hi Ferret. Thanks for joining the party! Sounds like useful info. From what you and McDave are saying, I can disconnect either the MAF sensor or the front oxygen sensor and the car will run? So, if it acts up while I'm out on the road this Sunday, I can always get home by disconnecting each of these devices (one at a time) and, assuming one of these devices actually is the culprit, when I disconnect the defective device, the car will begin running staisfactorily enough to drive home (even if its over a hundred miles)? Is this correct, guys? Also, why wouldn't either a shakey MAF sensor or faulty oxygen sensor set a code that will keep the MIL on? Gratefully, Mike V. PS I have not been able to get over to an Iron Pigs game yet, but I will before the season ends.... Link to comment Share on other sites More sharing options...
ferret Posted July 9, 2008 Share Posted July 9, 2008 1st, if you unplug the MAF, I think you have to cycle the key once or twice, to let the ECU know it's in a fail-safe mode. Try it before you need it to happen. Nothing like that to unplug the 02 sensor. I don't have an answer as to why it doesn't set a code, but I have seen where it doesn't. I'm not certain about driving a few hundred miles with the MAF disconnected, but I have driven from Albany to NJ with the 02 sensor unplugged. Link to comment Share on other sites More sharing options...
nipper Posted July 9, 2008 Share Posted July 9, 2008 1st, if you unplug the MAF, I think you have to cycle the key once or twice, to let the ECU know it's in a fail-safe mode. Try it before you need it to happen. Nothing like that to unplug the 02 sensor. I don't have an answer as to why it doesn't set a code, but I have seen where it doesn't. I'm not certain about driving a few hundred miles with the MAF disconnected, but I have driven from Albany to NJ with the 02 sensor unplugged. Unplugged O2 sensor might affect mileage and performance, might not, wont hurt anything. Driving in fail-safe mode dramatically reduces performance. O2 sensors get old and lazy, and wont throw a code always till they get really bad. nipper Link to comment Share on other sites More sharing options...
McDave Posted July 9, 2008 Share Posted July 9, 2008 Hi Ferret. Thanks for joining the party! Sounds like useful info. From what you and McDave are saying, I can disconnect either the MAF sensor or the front oxygen sensor and the car will run? So, if it acts up while I'm out on the road this Sunday, I can always get home by disconnecting each of these devices (one at a time) and, assuming one of these devices actually is the culprit, when I disconnect the defective device, the car will begin running staisfactorily enough to drive home (even if its over a hundred miles)? Is this correct, guys? Also, why wouldn't either a shakey MAF sensor or faulty oxygen sensor set a code that will keep the MIL on? Gratefully, Mike V. PS I have not been able to get over to an Iron Pigs game yet, but I will before the season ends.... I don't know that I would condone driving it with either one disconnected for 100 miles as it's just meant to be used as a diagnostic aid. One of the reasons OB99W likely asked if the mil was flashing is because that means the ecu has detected a fault that is serious enough to do damage to your cat converters. If you unplug the O2 sensor the ecu likely won't be able to make that determination without that input. If I were in your shoes and was able to determine one or the other was truly at fault, I would do my best to find a replacement as soon as possible with as few miles driven, keeping in mind continuing to drive it could end up costing big bucks for new cats, particularly if the light is flashing. Link to comment Share on other sites More sharing options...
nipper Posted July 9, 2008 Share Posted July 9, 2008 I don't know that I would condone driving it with either one disconnected for 100 miles as it's just meant to be used as a diagnostic aid. One of the reasons OB99W likely asked if the mil was flashing is because that means the ecu has detected a fault that is serious enough to do damage to your cat converters. If you unplug the O2 sensor the ecu likely won't be able to make that determination without that input. If I were in your shoes and was able to determine one or the other was truly at fault, I would do my best to find a replacement as soon as possible with as few miles driven, keeping in mind continuing to drive it could end up costing big bucks for new cats, particularly if the light is flashing. Disconnecting anything will keep the ecu in open loop mode. You wont damage the catalytic converters in this mode. This loop is desgned not to hurt anything. Same with limp mode. In limp mode, you may not even be able to drive over 50 mph. Link to comment Share on other sites More sharing options...
McDave Posted July 9, 2008 Share Posted July 9, 2008 Disconnecting anything will keep the ecu in open loop mode. You wont damage the catalytic converters in this mode. This loop is desgned not to hurt anything. Same with limp mode. In limp mode, you may not even be able to drive over 50 mph. I'm not so sure about that. There are tests that place the ecu in open loop that also recommend you not drive the car in that state. Suppose he has a rich condition caused by a leaking injector or pressure regulator? The cat will suffer. You may be right, but if you're not the consequences could be costly. Better to play it safe, imo. Link to comment Share on other sites More sharing options...
nipper Posted July 10, 2008 Share Posted July 10, 2008 I'm not so sure about that. There are tests that place the ecu in open loop that also recommend you not drive the car in that state. Suppose he has a rich condition caused by a leaking injector or pressure regulator? The cat will suffer. You may be right, but if you're not the consequences could be costly. Better to play it safe, imo. A leaky injector is going to happen weather he has every sensor plufgged in or not, that really is out of the scope of this discussion. The ECU has no control over a leaking injector (which would show up as a fouled plug with a tuneup). Also if it backfired it would trigger a flashing cel light (we would hope). Thats also why i suggested a fuel pressure gauge. nipper Link to comment Share on other sites More sharing options...
Mikevan10 Posted July 11, 2008 Author Share Posted July 11, 2008 Guys, Thank you very much for all of your thoughts and comments! Sorry for not reporting back sooner but I have been very busy. I'll try to comment more later but for now I'll just say that the car has not acted up AT ALL since I replaced the fuel filter and that was about 80 or 90 miles ago. That is not to say that I am certain that that was the cause of the problem. I have not forgotten that it seemed fine after we filled the gas tank only to re-occur some 40 miles later. BUT, I am confident enough that unless it re-occur between now and then, I am going to drive it to Jones Beach on Sunday. I will replace the air filter before I go. Possibly I'll hit the MAF sensor with the CRC too but I am thinking of not "disturbing" it until after my little trip. Again, many thanks. Talk to you soon. Mike Link to comment Share on other sites More sharing options...
McDave Posted July 11, 2008 Share Posted July 11, 2008 Have a good trip! Take the crc with you just in case. Link to comment Share on other sites More sharing options...
Mikevan10 Posted July 11, 2008 Author Share Posted July 11, 2008 It's already on the list! Thanks. Link to comment Share on other sites More sharing options...
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