firehawk618 Posted August 10, 2014 Author Share Posted August 10, 2014 To bring this back....I may have found my fix. Today I had a coil pack completely fail. I mean it was driving fine one second then the next I had a flashing CEL and definite loss of a cylinder. Running like complete crap. Coil pack had died completely. I had a spare laying around. I put it in and my car idles 10x smoother. It has NEVER idled this smooth since I had it. I did a short run on the highway and it seems my stumble is GONE!!!! I will know for sure after 2 days of commuting to work whether or not it's really gone but so far so good. The super smooth idle is a great sign I may have found the problem. Here's the thing. I have NEVER gotten a CEL for any kind of misfire. Never a pending code either. It wasn't like my car was misfiring at idle as we tend to think of a misfire. It was just not very smooth. 10' CTS-V, A6, Airraid, 2.4 upper, ID850's, self tuned. SOLD:06' LGT Wagon. BNR16G, Catless UP, DOWN, Hexmods VB, Hexmods diff bushings, BIG TMIC. Best 0-60: 4.651 by AP 1/4= 13.678@100.73 mph, 1.945 60', Automatic transmission. Link to comment Share on other sites More sharing options...
kzr750r1 Posted August 10, 2014 Share Posted August 10, 2014 Good catch. So it didn't fail often enough to produce a cel but was possible inherently weaker than the others and didn't have the kick fer smoothness? Given the heat cycles theses things are subjected to... your going to cause a run on new coil packs. Link to comment Share on other sites More sharing options...
firehawk618 Posted August 10, 2014 Author Share Posted August 10, 2014 Yeah that's about all I could figure. Weak enough to cause issues but not enough to trigger any CEL. When it totally failed today all at once the CEL came on flashing before I could even tell it had failed. I wish I had tested them earlier to see if they were reading within specs or not. Just because they read within specs does not mean they work correctly either though. I will report back after a few days of driving. If this solves it I will be pulling the other 3 and taking readings. I did order a set of 4 used ones from a member on here today, 2 are low mile ones 2 are not. 10' CTS-V, A6, Airraid, 2.4 upper, ID850's, self tuned. SOLD:06' LGT Wagon. BNR16G, Catless UP, DOWN, Hexmods VB, Hexmods diff bushings, BIG TMIC. Best 0-60: 4.651 by AP 1/4= 13.678@100.73 mph, 1.945 60', Automatic transmission. Link to comment Share on other sites More sharing options...
kzr750r1 Posted August 10, 2014 Share Posted August 10, 2014 Please do. Just thinking this is another, check this, if you nailed it. I'm not going to change mine at first during my rebuild. Only because I want to see if another theory of mine holds up. Should test them though. Having a sneaky suspicion this may be a precursor to head gasket failure. Well see after my rebuild if I'm having the surging feeling under steady load at speed. Link to comment Share on other sites More sharing options...
firehawk618 Posted August 11, 2014 Author Share Posted August 11, 2014 1 commute, MUCH improved. Still an ever so slight stumbling. My other 3 coils are just as old as the 1 I replaced. I don't have a headgasket issue. Well, if I do it shows none of they typical signs. Coolant loss, over pressurization of the cooling system, oil consumption, oil loss. I add zero coolant between oil changes and add zero oil between changes. 4k mile interval. 10' CTS-V, A6, Airraid, 2.4 upper, ID850's, self tuned. SOLD:06' LGT Wagon. BNR16G, Catless UP, DOWN, Hexmods VB, Hexmods diff bushings, BIG TMIC. Best 0-60: 4.651 by AP 1/4= 13.678@100.73 mph, 1.945 60', Automatic transmission. Link to comment Share on other sites More sharing options...
McDowell Performance Tunin Posted August 11, 2014 Share Posted August 11, 2014 Yeah, glad you found the issue. I think I have a few gray hairs from trying to tune it out. Just a few more slight tweaks to your OL MAF settings and you should be good to go. www.facebook.com/mcdowelltuning [sIGPIC][/sIGPIC] Click Here for Stage1, Stage2 and Stage3 Tuning and eTuning Info Link to comment Share on other sites More sharing options...
firehawk618 Posted August 12, 2014 Author Share Posted August 12, 2014 Commute #2. Idle still smooth and stumbling ALMOST completely gone. Waiting on replacement coil packs to see what happens. 10' CTS-V, A6, Airraid, 2.4 upper, ID850's, self tuned. SOLD:06' LGT Wagon. BNR16G, Catless UP, DOWN, Hexmods VB, Hexmods diff bushings, BIG TMIC. Best 0-60: 4.651 by AP 1/4= 13.678@100.73 mph, 1.945 60', Automatic transmission. Link to comment Share on other sites More sharing options...
firehawk618 Posted August 22, 2014 Author Share Posted August 22, 2014 Welp, the issue is still present exactly as before. So much for my coil pack solution. SMH Up next, going to throw some good ol' fashioned autolite copper plugs in and replace the cam sensors I never got around to swapping out. 10' CTS-V, A6, Airraid, 2.4 upper, ID850's, self tuned. SOLD:06' LGT Wagon. BNR16G, Catless UP, DOWN, Hexmods VB, Hexmods diff bushings, BIG TMIC. Best 0-60: 4.651 by AP 1/4= 13.678@100.73 mph, 1.945 60', Automatic transmission. Link to comment Share on other sites More sharing options...
JohnnyT Posted August 22, 2014 Share Posted August 22, 2014 I hope I'm not repeating what someone already stated here, but I don't have the time to read all 13 pages. As we all know this is a well know problem with the GTs. However, from what I read it is a tuning problem. Subaru tends to go rich with the fuel mixture when going from vaccum to boost in the 2500-2750 RPM range. It studders because it loads up with fuel. They do this to overcompensate from going lean where the engine cam detonate. A good tuner can get rid of this. I also hear that Cobb's maps in the AccessPort gets rid of this problem. Link to comment Share on other sites More sharing options...
McDowell Performance Tunin Posted August 23, 2014 Share Posted August 23, 2014 Chad, please send me data logs when you can. Thanks. www.facebook.com/mcdowelltuning [sIGPIC][/sIGPIC] Click Here for Stage1, Stage2 and Stage3 Tuning and eTuning Info Link to comment Share on other sites More sharing options...
firehawk618 Posted August 23, 2014 Author Share Posted August 23, 2014 I hope I'm not repeating what someone already stated here, but I don't have the time to read all 13 pages. As we all know this is a well know problem with the GTs. However, from what I read it is a tuning problem. Subaru tends to go rich with the fuel mixture when going from vaccum to boost in the 2500-2750 RPM range. It studders because it loads up with fuel. They do this to overcompensate from going lean where the engine cam detonate. A good tuner can get rid of this. I also hear that Cobb's maps in the AccessPort gets rid of this problem. Cobbs stage 1, stage 2 map did nothing to correct this on my car. 10' CTS-V, A6, Airraid, 2.4 upper, ID850's, self tuned. SOLD:06' LGT Wagon. BNR16G, Catless UP, DOWN, Hexmods VB, Hexmods diff bushings, BIG TMIC. Best 0-60: 4.651 by AP 1/4= 13.678@100.73 mph, 1.945 60', Automatic transmission. Link to comment Share on other sites More sharing options...
firehawk618 Posted August 23, 2014 Author Share Posted August 23, 2014 Chad, please send me data logs when you can. Thanks. Logan, sorry for dragging my feet. Super busy at work, tons of O.T. Went to replace my front brake rotors / pads yesterday. Had to hammer off a rotor only to discover my new rotors purchased online were the WRONG diameter. UGNNN Got regular blanks on order locally, should have them on tomorrow and I'm on vacation next week. Logs tomorrow night. 10' CTS-V, A6, Airraid, 2.4 upper, ID850's, self tuned. SOLD:06' LGT Wagon. BNR16G, Catless UP, DOWN, Hexmods VB, Hexmods diff bushings, BIG TMIC. Best 0-60: 4.651 by AP 1/4= 13.678@100.73 mph, 1.945 60', Automatic transmission. Link to comment Share on other sites More sharing options...
kzr750r1 Posted August 23, 2014 Share Posted August 23, 2014 I hope I'm not repeating what someone already stated here, but I don't have the time to read all 13 pages. As we all know this is a well know problem with the GTs. However, from what I read it is a tuning problem. Subaru tends to go rich with the fuel mixture when going from vaccum to boost in the 2500-2750 RPM range. It studders because it loads up with fuel. They do this to overcompensate from going lean where the engine cam detonate. A good tuner can get rid of this. I also hear that Cobb's maps in the AccessPort gets rid of this problem. When new this was never an issue... After long in the tooth it became an issue. Even with the eye of a respected tuner on my logs it was still present. Now that I'm refreshing the motor will be curious to see if this may just be mechanical. Possible symptom of HG failure. I'm saying this because mine was slowly getting worse as I was convincing myself for sure what was going on. Cylinders and valves look fantastic for 160K on them. I am going to change is the crank position sensor. Cam sensors were replaced 20K ago after a cel event that only happened once. Pistons and bearings are about the only hard parts I hope to need. That and a few buckets for valve lash adjustment. Will report back in Mid September. Link to comment Share on other sites More sharing options...
McDowell Performance Tunin Posted August 23, 2014 Share Posted August 23, 2014 Chad has larger injectors and turbo as well. The difficulty is the issue seemed to be resolved, but has returned. We still have some tweaking to do. Resetting the TCU after each flash is recommended, to remove any learned settings. www.facebook.com/mcdowelltuning [sIGPIC][/sIGPIC] Click Here for Stage1, Stage2 and Stage3 Tuning and eTuning Info Link to comment Share on other sites More sharing options...
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