prwood Posted August 24, 2015 Share Posted August 24, 2015 Hi all, I have a 2002 Legacy L Wagon, as described in my intro post: http://www.ultimatesubaru.org/forum/topic/155139-eight-year-subaru-owner-first-time-subaru-board-poster/ For the past year or so, it's been having an issue where the engine sputters at RPMs below 2000. The sputter never occurs at RPMs above 2000, and it also stops once the car has been driven around for an hour or two, and will stay good between rides that same day as long as it's not more than a few hours apart. Unfortunately as it's used for a lot of city driving, it is frequently under 2000 RPM so the sputter happens on a regular basis. Also, during the winter when the outside temps are extremely cold, it takes even longer for the sputtering to stop, if it does stop at all. The engine has given the following codes: P0604 ICM RAM errorP1518 starter switch circuit low inputP0301 cylinder 1 misfireP0302 cylinder 2 misfireP0303 cylinder 3 misfireP0304 cylinder 4 misfireP0420 catalyst system efficiency below threshold bank 1P0456 Evap emission system leak detected (very small leak) (I'm not sure if all of them are related to the sputter.) We've tried replacing the spark plugs numerous times (they show a black ring around the top, which I believe indicates carbon build-up), as well as spark plug cables, replaced some of the sensors (I don't have the list right now but I can probably find out if needed), tried resetting the ECU by disconnecting the battery, tried using a tank of high-octane gas, and other standard things like oil changes, but the sputter still persists. As of today, after the ECU reset and a day of normal city driving, I'm getting the following codes: P1518 starter switch circuit low inputP0301 cylinder 1 misfire I've read up a bit in the forums that the engine used in this model year and the two earlier was fairly problematic, and I'm wondering if there are any other things we could try other than swapping out the engine. Thanks, Peter Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted August 25, 2015 Share Posted August 25, 2015 How long has it been, and how many miles on the car, since new spark plugs and plug wires have been put on this car?? PO301 1 misfire code may be telling you to change the plugs and wires. If wires and plugs were replaced recently, I hope you installed wires costing around $50 a set, and NKG sparkplugs. Cheap wires from an auto parts store, and plugs just don't work well in a Subie. Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted August 25, 2015 Share Posted August 25, 2015 (edited) I'm kinda concerned you may have more than one problem.a possible cause of the poor-running until after warm-up might be a bad engine temp sensor.in newer soobs it shares the same housing as the temp gauge sender - 3-wire unit.the FSM (or someone here) may know of a way to test it if you don't want to just swap it out.as alluded above - old wires can cause misfires, particulalry in moist/wet weather. heat dries the engine compartment and misfiring is reduced. As a tes, when it is idling smoothly after warm-up, pop the hood and spray the spark plug wires and the coil with a plant mister of tap water. If the engine stumbles, could be time for new wires/coil. Oil on the plug wire boots is another source of misfiring. plug tubes should be dry. Edited August 25, 2015 by 1 Lucky Texan Quote Link to comment Share on other sites More sharing options...
wtdash Posted August 25, 2015 Share Posted August 25, 2015 Hi THIS POST may be helpful RE: the starter. The Misfire is unfortunately another (besides HG) Achilles Heel of Subarus. I'd be suspicious of the coil pack and if you've NOT done the VC gasket and plug seals, they're due. Also, since you've been dealing w/this for so long, I'd get a Compression and Leak Down Test done - not cheap, but neither is throwing parts @ it. GL, Td Quote Link to comment Share on other sites More sharing options...
wtdash Posted August 25, 2015 Share Posted August 25, 2015 (edited) I'm kinda concerned you may have more than one problem. a possible cause of the poor-running until after warm-up might be a bad engine temp sensor. +1 Yes...they wear out and cheap. Td Edited August 25, 2015 by wtdash Quote Link to comment Share on other sites More sharing options...
prwood Posted August 25, 2015 Author Share Posted August 25, 2015 How long has it been, and how many miles on the car, since new spark plugs and plug wires have been put on this car?? PO301 1 misfire code may be telling you to change the plugs and wires. If wires and plugs were replaced recently, I hope you installed wires costing around $50 a set, and NKG sparkplugs. Cheap wires from an auto parts store, and plugs just don't work well in a Subie. The spark plugs and wires were changed about a year ago, and I just changed the spark plugs again this week. The sparkplugs and wires are both NGK. Quote Link to comment Share on other sites More sharing options...
prwood Posted August 25, 2015 Author Share Posted August 25, 2015 I'm kinda concerned you may have more than one problem. a possible cause of the poor-running until after warm-up might be a bad engine temp sensor. in newer soobs it shares the same housing as the temp gauge sender - 3-wire unit. the FSM (or someone here) may know of a way to test it if you don't want to just swap it out. as alluded above - old wires can cause misfires, particulalry in moist/wet weather. heat dries the engine compartment and misfiring is reduced. As a tes, when it is idling smoothly after warm-up, pop the hood and spray the spark plug wires and the coil with a plant mister of tap water. If the engine stumbles, could be time for new wires/coil. Oil on the plug wire boots is another source of misfiring. plug tubes should be dry. Thank you for the suggestions. I will do some research on the engine temp sensor and will also try the water spray test. Quote Link to comment Share on other sites More sharing options...
prwood Posted August 25, 2015 Author Share Posted August 25, 2015 Hi THIS POST may be helpful RE: the starter. Thanks, I'll take a look at it. The Misfire is unfortunately another (besides HG) Achilles Heel of Subarus. I'd be suspicious of the coil pack and if you've NOT done the VC gasket and plug seals, they're due. Also, since you've been dealing w/this for so long, I'd get a Compression and Leak Down Test done - not cheap, but neither is throwing parts @ it. GL, Td I'll check with my father-in-law to see if he's done the coil pack and vc (valve cover?) gasket and plug seals. I feel as though the coil pack may have been done but I don't think the other has been done. Is the compression and leak down test something I can do at home? Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted August 25, 2015 Share Posted August 25, 2015 might be the coil - or oil on the wire boots from leaky gaskets. do you ever smell fuel around the fill door? some folks get holes in the filler neck causing evap codes. they rust behind the plastic cover. Also, poor gas cap seal and cracked rubber hoses, etc. can cause evap leak codes. Quote Link to comment Share on other sites More sharing options...
prwood Posted August 25, 2015 Author Share Posted August 25, 2015 +1 Yes...they wear out and cheap. Td Is the 'engine temp sensor' the same as the engine coolant sensor? That's what I'm finding when I google for 'engine temp sensor'. Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted August 25, 2015 Share Posted August 25, 2015 (edited) yep - it'd be nice if we had some ohm or voltage test to try first, but..... Edited August 25, 2015 by 1 Lucky Texan Quote Link to comment Share on other sites More sharing options...
prwood Posted August 25, 2015 Author Share Posted August 25, 2015 According to my FIL, the ECT sensor is one of the first things he replaced when he was trying to troubleshoot the issue, and he said it didn't seem to make a difference. He said it's possible the replacement unit may have been defective, but I'm not sure how likely that is. In any case, it looks like it costs about $10, so would it be worth trying to replace it again? Any recommendations on brand or seller? I generally order online from Rock Auto if it's not something I need immediately. Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted August 25, 2015 Share Posted August 25, 2015 nah, I wouldn't replace it again. getting some data from the ecu might be helpful. maybe something mechanical is changing? a valve sticking when cold maybe? compression and leakdown test might be good, dropping the exhaust manifold and looking dropped valve guides might be helpful. Quote Link to comment Share on other sites More sharing options...
prwood Posted August 25, 2015 Author Share Posted August 25, 2015 I am considering replacing the valve cover gaskets. Any recommended (or not recommended) brand for parts? Prices seem to range from $11 to $41. I can also check out the valves while I'm in there. Quote Link to comment Share on other sites More sharing options...
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