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Old 07-27-2021, 07:34 PM   #1
DaveRosario
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Default 2014 WRX All Cyl misfires/stumble while cruising No codes

Hi Guys,

I've been trying to figure this one out but I'm running out of Ideas. I'm starting to think it's the ACT lightweight flywheel causing these misfires. But please let me know what you think. Logs Here

Symptoms:
  • Random misfires on all cylinders.
  • The Roughness Monitoring reads up to 5 counts between 2000-3100 RPMs.
  • UP to 2 counts at idle.
  • Can feel and hear the misfires.
  • Car idle is a little rough even when there are no misfires registered.
  • Car doesn't seem to be losing any power. It just stumbles
  • No FBK or FLK only -1.40 FBK when the AC compressor turns ON

Mods/Parts:
  • Tye RA short block
  • N-Group engine mounts
  • Process West VertiCooler
  • Forge BPV
  • 2014 WRX D25 heads
  • TGV deletes
  • FIC 1200cc injectors
  • AEM 320 Fuel Pump
  • Radium Rails (in parallel)
  • Radium Dampers on both rails
  • Radium FPR-D, Fuel Pressure Regulator-Damper
  • Fluidampr (Harmonic balancer)
  • Grimmspeed catted downpipe
  • MAC 3 ports EBC
  • IAG AOS
  • ACT HD Clutch
  • ACT streetlight Flywheel
  • New OEM MAF sensor
  • New OEM Knock sensor
  • New NGK AFR sensor (Front O2 sensor)
  • New OEM Ignition Coils
  • New NGK (OEM) Spark Plugs (.030" gap)
  • New Engine Wiring harness (latest revision)
  • New Alternator
  • New Crankshaft Sensor
  • New Camshaft Sensors







Troubleshooting:

Compression test:
Cyl#1 = 152 psi
Cyl#2 = 152 psi
Cyl#3 = 152 psi
Cyl#4 = 150 psi
Leak Down Test:
Cyl#1 = 2%
Cyl#2 = 2%
Cyl#3 = 2%
Cyl#4 = 5%
  • Did multiple Pressurized vacuum leak (smoke test) and boost leak tests but not leaks.
  • Logs show steady AFR between 14.5 - 15. While cruising/idling and misfires present.
  • Tested the BPV for leaks or weak spring
  • Fuel trims seem on point (less than 5%)
  • Both AVCS advance seems to be in sync (up to 3 deg difference when accelerating)
  • Replaced the OEM AFR sensor with a new NGK AFR sensor
  • Tried 2 different OEM MAF sensors
  • Re-installed the OEM fuel Injectors
  • Added a ground cable from the Negative pole to the Alternator housing.
  • Tune is basically stock, exempt for the tables that affect fueling to calibrate the new FIC 1200cc injectors, Wastegate tables for the boost controller and TGV cel codes disabled tables.
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Last edited by DaveRosario; 07-27-2021 at 07:39 PM.
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Old 07-27-2021, 08:35 PM   #2
K3rm1tth3fr0g
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What type of fuel?
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Old 07-27-2021, 10:15 PM   #3
DaveRosario
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Quote:
Originally Posted by K3rm1tth3fr0g View Post
What type of fuel?
Shell 91 ACN.
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Old 07-27-2021, 10:24 PM   #4
AliBenn
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Jeez
Such good information above
Normally would not say this bc usually a wild goose chase for people that do not know anything to do with engines(refusing to do compression/leak D tests)
But
If compression good(great)
If leak down good(great)
Obviously have spark
Fuel?
Despite fuel trim readings?

Hell the next thing I would think of is ground but u added so Thats not it

Puzzled
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Old 07-27-2021, 11:05 PM   #5
DaveRosario
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Quote:
Originally Posted by AliBenn View Post
Jeez
Such good information above
Normally would not say this bc usually a wild goose chase for people that do not know anything to do with engines(refusing to do compression/leak D tests)
But
If compression good(great)
If leak down good(great)
Obviously have spark
Fuel?
Despite fuel trim readings?

Hell the next thing I would think of is ground but u added so Thats not it

Puzzled
Thanks for trying to help. I've been chasing this Issue for awhile now. Almost everything is new. Only thing left is the light weight Flywheel, but some people say it might not be that.
I tried different gas stations before but nothing. The fricking car is hunted lol. Other than those few misfires the car starts, runs and drive as it should and it has power, but I try to to not get on boost for now.

If I cruise at 3500 RPMs I Don't see or feel the misfires and the Roughness Monitoring stays at 0 on all Cyls. I don't know this one is driving me crazy!

I'll replace the flywheel this hopefully this weekend.

Last edited by DaveRosario; 07-27-2021 at 11:16 PM.
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Old 07-28-2021, 01:09 AM   #6
Elbert Bass
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Quote:
Originally Posted by DaveRosario View Post
Thanks for trying to help. I've been chasing this Issue for awhile now. Almost everything is new. Only thing left is the light weight Flywheel, but some people say it might not be that.
I tried different gas stations before but nothing. The fricking car is hunted lol. Other than those few misfires the car starts, runs and drive as it should and it has power, but I try to to not get on boost for now.

If I cruise at 3500 RPMs I Don't see or feel the misfires and the Roughness Monitoring stays at 0 on all Cyls. I don't know this one is driving me crazy!

I'll replace the flywheel this hopefully this weekend.
Before you go to all the trouble: Lightweight flywheels usually cause non-symptomatic misfire or roughness readings. Usually intermittent P0300, flashing CEL - all without discernible physical symptoms of an actual misfire. It is a false misfire reading due to the flywheel's lack of mass and inertia.
The ECM determines misfire by monitoring the minute variations in crankshaft speed between cylinder ignition.
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Old 07-28-2021, 01:49 AM   #7
AliBenn
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Wow Bass
Good freakin call
OP
Plz let us know what happens after GLUP flywheel install

I would think that tuner would of anticipated this thou
Just AP tune?

Might have buckle down and get AWD tune done
Hell
I would rather pay $750 than RR a flywheel in this TX heat 100%
(Where I stay)
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Old 07-28-2021, 01:59 AM   #8
DaveRosario
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Quote:
Originally Posted by Elbert Bass View Post
Before you go to all the trouble: Lightweight flywheels usually cause non-symptomatic misfire or roughness readings. Usually intermittent P0300, flashing CEL - all without discernible physical symptoms of an actual misfire. It is a false misfire reading due to the flywheel's lack of mass and inertia.
The ECM determines misfire by monitoring the minute variations in crankshaft speed between cylinder ignition.
Thanks for the reply!
That's what I've been reading. But I still gonna change it. I'm tired of the gear rattle and other vibration that comes with it. I'm not really expecting that to fix the problem.

What else you guys think timing? the ECU?
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Old 07-28-2021, 02:05 AM   #9
DaveRosario
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Quote:
Originally Posted by AliBenn View Post
Wow Bass
Good freakin call
OP
Plz let us know what happens after GLUP flywheel install

I would think that tuner would of anticipated this thou
Just AP tune?

Might have buckle down and get AWD tune done
Hell
I would rather pay $750 than RR a flywheel in this TX heat 100%
(Where I stay)
I will keep you guys posted.
I'm in LA and is not that hot yet. It shouldn't take me that long to change the flywheel. Probably like 4-6 hours. Believe it or not It's easier for me to remove the engine than the transmission. Plus while the engine is out I'm gonna test the EGR valves for leaks.

Last edited by DaveRosario; 07-28-2021 at 02:28 AM.
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Old 07-28-2021, 02:26 AM   #10
DaveRosario
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Here is another log of my commute from work.
There is a period where I keep the car above 34k RPMs and there are no misfires. Once I go below 31k RPMs the misfires start and I can feel the car stumbling.

Thanks for helping!

Last edited by DaveRosario; 07-28-2021 at 02:40 AM.
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Old 07-28-2021, 02:40 AM   #11
DaveRosario
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Old 08-10-2021, 08:50 PM   #12
DaveRosario
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Update:
Replaced the Flywheel with an OEM one.
Re checked the timing (timing was off by 1/2 a tooth but It's perfect now)
Re checked for vacuum leaks (all good)

Car still have about 1 count misfire randomly on any cylinder, but with half of the frequency now. I think the extra weight of the OE Flywheel kind of damper the speed fluctuation in the crank no the "light" misfires are not registered by the ECU but I can feel the car stumbling.

I'm revising the injectors tune. But I seems like the AFRs are ok.

I'll keep you guys posted.
Please let me know if you have any other Ideas.
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Old 08-11-2021, 09:27 AM   #13
pigboat_2
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Timing was just casually off "1/2 a tooth"? Uhh...

Spend the 250-300 and get a real tune.
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Old 08-11-2021, 09:38 AM   #14
K3rm1tth3fr0g
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Get a tune...
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Old 08-11-2021, 10:47 AM   #15
aidanmurphy
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Get n professional e-tune for peace of mind. I recommend Eric at Torqued Performance
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Old 08-11-2021, 10:50 AM   #16
Jaywal94
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Id also recommend a tune. Just had Clark Turner do mine. Hes excellent to work with.

Seems odd that your timing would be off at all. Seems sketchy to me. LOL
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Old 08-13-2021, 08:44 PM   #17
AliBenn
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Wha Happan?
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Old 08-13-2021, 09:15 PM   #18
SJSC1608NJ
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Any updates? I have a 2014 I have been chasing since I bought mine as well. Zero miles on it. Dealer replaced the engine harness, replaced plugs. I replaced all my grounds and plugs again. But i have 3 of them misfiring. Going to do coil packs next I guess.
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Old 08-14-2021, 04:21 AM   #19
DaveRosario
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Quote:
Originally Posted by SJSC1608NJ View Post
Any updates? I have a 2014 I have been chasing since I bought mine as well. Zero miles on it. Dealer replaced the engine harness, replaced plugs. I replaced all my grounds and plugs again. But i have 3 of them misfiring. Going to do coil packs next I guess.
No, I don't think is the tune as others pointed out. My fuel trims are pretty good the car doesn't run lean or rich at any time. When the misfires happen fuel trims are good. So I think it might be something electrical. I had a blown piston #4 in the previous engine and the some how the spark plug electrode was touching the electrode ground. So I'm not sure if that messed something else. I have new OEM coils and Engine harness installed. But still trying to figure out the issue. Next I'm checking the ECU to Engine Bay Harness. Please let me know if you find a solution first. Thanks
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Old 08-15-2021, 08:04 PM   #20
AliBenn
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Crap Man
Still no OBD codes?

Let us know
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Old 08-15-2021, 08:52 PM   #21
benflynn
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I thought it was exedy hyper clutch giving me missfires, but Im sure its my dw1300s, it all went together at once. My misfires go away on E85 so Id like nicer injectors
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Old 08-15-2021, 09:08 PM   #22
SJSC1608NJ
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Quote:
Originally Posted by DaveRosario View Post
No, I don't think is the tune as others pointed out. My fuel trims are pretty good the car doesn't run lean or rich at any time. When the misfires happen fuel trims are good. So I think it might be something electrical. I had a blown piston #4 in the previous engine and the some how the spark plug electrode was touching the electrode ground. So I'm not sure if that messed something else. I have new OEM coils and Engine harness installed. But still trying to figure out the issue. Next I'm checking the ECU to Engine Bay Harness. Please let me know if you find a solution first. Thanks

My codes I get are P0000, P0301,P0302,P0303...Sometimes I get 4. I will let you know. Ill let you know what I find. Good luck!
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Old 08-15-2021, 09:28 PM   #23
AliBenn
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Without even pulling those codes
All misfires multiple cylinders
Hmmmm lemme think
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Old 08-15-2021, 09:42 PM   #24
DaveRosario
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Quote:
Originally Posted by SJSC1608NJ View Post
My codes I get are P0000, P0301,P0302,P0303...Sometimes I get 4. I will let you know. Ill let you know what I find. Good luck!
Ohh if your car is throwing codes it should be easier to figure out. Check the coils. Also log the roughness monitors and AFR, verify that your car is not running lean when the misfires happen. Did you do a compression and leakdown test? if not you should. If that's OK Then double check the timing belt is good and timing is all sync up.
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Old 08-15-2021, 09:47 PM   #25
DaveRosario
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Quote:
Originally Posted by AliBenn View Post
Crap Man
Still no OBD codes?

Let us know
No codes, because it doesn't reach the threshold max misfire count is 3 rarely. But Usually is 1.
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