robmat Posted October 13, 2013 Share Posted October 13, 2013 Ok, this has happened twice now and I am starting to get a little concerned. Here is what is going on: 1. I have had the P0301 code since purchasing the car 2 months ago. It currently has 132000k and is stock. It comes and goes and I have cleared the code a few times. 2. As part of trying to address the code, I recently changed the plugs (and changed the diff and trans fluid at the same time). I discovered that the NGK LFR6AIX-11 plugs were installed. I replaced those with NGK SILFR6A. While doing this I also found that the rear passenger side coil pack harness had a broken clip. 3. The first incident was after clearing the P0301 and P2096 codes (this was the first time I had seen the P2096). I cleared the codes at a rest area on the interstate. No crazy driving, just highway cruising. After the codes were reset, the car would not turn over. It started after the third try, but the idle dropped and the car stalled. I started it again, kept the revs a little higher and began to drive. The car drove just fine, though the CEL did come back on. 4. The car was fine for a few days until I decided to clear the codes again (only P0301). I did so and had the same starting issue. I have not cleared the codes since and have had no trouble with starting. I used the OBD with no issues prior to the last work day (Trans, diff, and plugs). I have had the battery and starter checked and both are ok. I did have a little trouble putting the pass rear coil pack clip/harness back on and wonder of that is the issue or part of it. I have since used MAF cleaner on the MAF and visually checked all hoses and lines. The only other thing I have done to the car is to replace the banjo bolt/filter. The car also has what I would describe as a rough idle, almost a shudder at times. This and the P0301 prompted the plug change. So, has anyone had any experience with this and is the clip/harness a part that I can source and replace? I have considered using Seafoam, but haven't yet. Thanks! Link to comment Share on other sites More sharing options...
iNVAR Posted October 13, 2013 Share Posted October 13, 2013 The starting issue is a result of the ECU rebooting. Happens whenever you reset the ECU or lose battery power. Next time turn your ignition to the ON position, but do not crank for about 5 seconds (wait until the gauges are done sweeping and count to 3.) THEN start. The low idle/stalling is a result of the reset, since you wiped out the idle learning. The car needs to relearn the correct idle. Stop clearing your codes all the time and go fix your problem. The code pops up for a reason. Swap coil packs from one cylinder to another, reset, and see if the code changes to a misfire on a different cylinder. Link to comment Share on other sites More sharing options...
robmat Posted October 13, 2013 Author Share Posted October 13, 2013 I realize they come up for a reason. I started with the plugs and will work through a list of things I've found on the forum that are related to the P0301 and rough idle. Thanks for the input about the reset, I didn't realize that was an issue or common occurrence. My old RS never did anything like that. So then, would the change in plugs (going from the stage colder to stock) affect the idle? Link to comment Share on other sites More sharing options...
Max Capacity Posted October 13, 2013 Share Posted October 13, 2013 No, colder plugs will not effect idle. You have a miss fire on #1. swap coils with #3 and see if the miss fire code follows it. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
robmat Posted October 13, 2013 Author Share Posted October 13, 2013 Ok, just curious about that.... I'll working on switching those coil and see what happens. I assume that it may be the coil pack if the code follows it to #3? Link to comment Share on other sites More sharing options...
iNVAR Posted October 13, 2013 Share Posted October 13, 2013 Correct. Link to comment Share on other sites More sharing options...
m sprank Posted October 13, 2013 Share Posted October 13, 2013 Cold plugs can absolutely effect idle. If they get fouled (which they do far easier than standard heat range plugs). Must get colder plugs hot often enough to keep them clean. No street driven Subie needs cold plugs. We even use standard heat range in 500whp+ Subies and our track cars. Cold plugs are generally a stop gap for a lazy tuner. Link to comment Share on other sites More sharing options...
robmat Posted October 13, 2013 Author Share Posted October 13, 2013 Great! I thought I was doing the right thing by going back to the stock plugs. Link to comment Share on other sites More sharing options...
m sprank Posted October 13, 2013 Share Posted October 13, 2013 Set gap to 0.028". If it still happens, swap coils, then injectors (if you dont have the tools to test). If that does nothing, could be an exhaust valve starting to pound itself flat and it is the beginning of needing to pull the motor (worst case scenario). Link to comment Share on other sites More sharing options...
ehsnils Posted October 14, 2013 Share Posted October 14, 2013 Just look for leaks around the manifold before you pull the engine. A leaking hose or manifold/cylinder head gasket could also cause problems. Same with quirky sensors - MAF and MAP sensors. Link to comment Share on other sites More sharing options...
robmat Posted October 15, 2013 Author Share Posted October 15, 2013 Is the harness that attaches to the coil pack something I can easily find? Link to comment Share on other sites More sharing options...
robmat Posted October 15, 2013 Author Share Posted October 15, 2013 As in....I'm not quite sure what to call it...? Link to comment Share on other sites More sharing options...
ehsnils Posted October 15, 2013 Share Posted October 15, 2013 Is the harness that attaches to the coil pack something I can easily find? Just follow the wires. Or if you mean the clip - just check with the dealer or use a zip tie. Link to comment Share on other sites More sharing options...
m sprank Posted October 15, 2013 Share Posted October 15, 2013 I have replacement clips for the coil pack connectors. Link to comment Share on other sites More sharing options...
robmat Posted October 19, 2013 Author Share Posted October 19, 2013 Alright. Finally got the chance to swap coil packs. The code did not follow....I am still getting P0301 and got P2096 again. Injectors next I guess... Link to comment Share on other sites More sharing options...
JmP6889928 Posted October 19, 2013 Share Posted October 19, 2013 Make sure you didn't crack the porcelain on that particular plug when you installed it. It's very easy to do and can cause a bunch of different hard to trace problems. Link to comment Share on other sites More sharing options...
ehsnils Posted October 19, 2013 Share Posted October 19, 2013 And check valve clearance too. Even if a compression test checks out it can still be a valve clearance problem. Link to comment Share on other sites More sharing options...
m sprank Posted October 19, 2013 Share Posted October 19, 2013 Leak down test will show if valves are leaking by. Many times in a Subie cyl #2 or #4 will begin to pound the exhaust valves flat. Misfire at idle is the first sign of this. It eventually leads to a cracked/split/broken valve. I eluded to this earlier, but hope it is the worst case scenario. Link to comment Share on other sites More sharing options...
ehsnils Posted October 20, 2013 Share Posted October 20, 2013 Considering that the valves get hotter than the head they expand more when warm, so it's not entirely conclusive with a leakdown test. It depends on how far it has gone. Best is to check the clearance to see that it's within specs. Link to comment Share on other sites More sharing options...
m sprank Posted October 20, 2013 Share Posted October 20, 2013 Have you ever checked valve clearance in car on a 4th gen LGT??? Even if you wanted to waste that much time and frustration, then found a loose or tight valve, you wont want to swap buckets in car. Taking that much of the head apart in car is a waste of time. Leak down test and watch cylinder roughness on all four cylinders while the car is running. If your really good with a bore scope you can see the bad valve sometimes. Simple enough to find a leaking valve. But if you do find one, motor is coming out and you might as well freshen up the heads (I would recommend new valve guides too), hone and install new rings and bearings at a minimum. Link to comment Share on other sites More sharing options...
robmat Posted October 20, 2013 Author Share Posted October 20, 2013 Well, I figure the valve may indeed be the worst case scenario, but I'mm going to do an injector rebuild next and go from there. So fingers crossed. If it does require pulling the engine, I might as well go ahead and button everything else up. Thanks for all of the help guys! Link to comment Share on other sites More sharing options...
ehsnils Posted October 20, 2013 Share Posted October 20, 2013 Have you ever checked valve clearance in car on a 4th gen LGT??? Even if you wanted to waste that much time and frustration, then found a loose or tight valve, you wont want to swap buckets in car. Taking that much of the head apart in car is a waste of time. Leak down test and watch cylinder roughness on all four cylinders while the car is running. If your really good with a bore scope you can see the bad valve sometimes. Simple enough to find a leaking valve. But if you do find one, motor is coming out and you might as well freshen up the heads (I would recommend new valve guides too), hone and install new rings and bearings at a minimum. I have done the engine on a STi... So I can imagine... Link to comment Share on other sites More sharing options...
StoplightAssassin Posted October 20, 2013 Share Posted October 20, 2013 I know you said you checked the hoses, but did you get the vac lines under the IC too? Could be a clogged fuel filter also. Link to comment Share on other sites More sharing options...
robmat Posted October 21, 2013 Author Share Posted October 21, 2013 Is there a diagram that shows the location of all of the vac lines? I'm checking everything I can, but am still new to the turbo'd subies.. Link to comment Share on other sites More sharing options...
m sprank Posted October 22, 2013 Share Posted October 22, 2013 Fuel filter is integrated to the fuel pump assembly. To replace it, you replace the entire assembly. Vac diagram for you. Link to comment Share on other sites More sharing options...
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