Welcome to the North American Subaru Impreza Owners Club Sunday November 17, 2019
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Normally Aspirated Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 10-16-2019, 01:35 PM   #1
Gamil
Scooby Newbie
 
Member#: 220375
Join Date: Aug 2009
Chapter/Region: MAIC
Location: Philadelphia, PA
Vehicle:
2011 Outback Sport
Blue

Default #2 Misfire after rebuild, 2011 OBS

Had to rebuilt an EJ253 due to rod knock. Got it all back together and I'm having misfires on cylinder #2, P0302. Always the same cylinder. List of work:

Machine Shop:
- Cleaned all aprts
- checked clearances/sizes of crank, pistons, cylinders etc
- Valve job
- Assembled valves+springs into heads with new OEM springs

My work:
- Disassemble everything except valves+springs , drop off at machine shop
- reassembled everything except valves+springs, with all new bolts, OEM gasket/seal kit
- followed FSM religiously
- Chopped heat sheilds off OEM exhaust headers because harmonic death rattle. Applied DEI Titanium Exhaust wrap.


"Upgrades"
- Delta Cams, 1000 grind
- ACT XACT StreetLite LW Flywheel (ACT600705)
- Exedy Stage 1 Organic Clutch disk (EXE15801)
- King Race Bearings
- STI Rods (pulled from "new" STI getting prepped by race shop)
- New Spark Plugs, NGK Iridium IX
- New Plug Wires, Duralast "Gold" (do plug wires make any difference?)
- New OEM Knock Sensor and wiring harness b/c I'm a clutz
- "Group N" Mounts (D1010FE020, D1010FE110, D1010FE120)


From my forum readings, there's a good chance of a "phantom" misfire due to either the cams or the LWFW, and combined it's pretty much guaranteed. But, there have been a few times where I've felt a misfire. Or, rather, RPMs dropped for seemingly no reason. Idle with all electronics off (radio, headlights, fan, AC) is pretty stable, but if I turn on ventilation, then sometimes as the radiator fan kicks on/off, the RPMs drop low, and stall on rare occasion.

This weekend, I drove it to an autocross, had cruise control on the whole ride, no hiccups. Once I arrived in paddock, let the car Idle while I put air in the tires, and that's when revs dropped out and code pops up. After that, ran smooth rest of the event and all the way home.

I reset the code yesterday, and then last night, again, P0302 pops up while I'm sitting at a light, but the revs didn't drop this time.

There have been a couple times that I noticed the engine lugging/bucking around 2500rpm under light acceleration, and shortly after while idling the code popped up.

Compression test: 1955psi on all cylinders
Swapped Fuel Injectors between #2 and #4. No change

After work today I'm planning to Gap the spark plugs, and tomorrow I'll check the valve lash (reaaaaly, don't want to have to fix that with the engine in the car. Was annoying enough with the heads on a workbendth)

EDIT: ***Troubleshooting Summary to date***

- Compression test: 1955psi on all cylinders
- Swapped Fuel Injectors between #2 and #4
- checked plugs:
--- #2 is sooty
--- the rest are A-OK
--- Gaps are good
- Swapped plugs
- Swapped plug wires between 2/4
- Swapped coil pack connection point between 1 & 2 (b/c wasted spark)
- Tested Coil pack resistances: almost bang on spec, well within tolerance)
- Tested plug wire resistances: Only #4 was out of spec, low
- Checked valve Lash
--- found and corrected +0.003" on secondary intake ie the variable one, noticable decrease in valve noise.
- Timing checks out, with both the pulley marks and what's left of the lines on the belt.
- Replaced the broken ground strap, no change
* Registered users of the site do not see these ads.

Last edited by Gamil; 11-10-2019 at 04:35 PM. Reason: consolidating Troubleshooting to OP
Gamil is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 10-18-2019, 12:47 AM   #2
mikeofree
Scooby Newbie
 
Member#: 491039
Join Date: Sep 2018
Chapter/Region: BAIC
Location: Northern California
Vehicle:
2008 Impreza 2.5i
DMG

Default .

Maybe its your ignition coil? https://www.subarupartsdeal.com/part...2433aa580.html

It's the assembly that all of your spark plug wires lead into.
mikeofree is offline   Reply With Quote
Old 10-19-2019, 04:16 PM   #3
awfulwaffle
Scooby Newbie
 
Member#: 409332
Join Date: Dec 2014
Location: SE MI/SE WI
Vehicle:
2013 WRX
PBP

Default

Try moving the plugs too. When I built the motor in my LGT, I had an intermittent miss on #1, that eventually turned into a dead miss and popped code. Turned out to be a bad (brand new) NGK plug. Easy enough to do before digging into valve clearances. Friend of mine recently went to replace the plugs in his FXT, and had two bad ones in the set. LFR7AIX for us so not the same plugs you used, but who knows.
awfulwaffle is offline   Reply With Quote
Old 10-23-2019, 09:18 PM   #4
Gamil
Scooby Newbie
 
Member#: 220375
Join Date: Aug 2009
Chapter/Region: MAIC
Location: Philadelphia, PA
Vehicle:
2011 Outback Sport
Blue

Default

I did gap the plugs today and they all measured fine. But, #2 is slightly sooty. The rest looked perfect (no soot, no oil, no white spots, just brown/grey)

@awfulwaffle: huh, alright. That's easy. I'll try swapping #2 and #4, and see if the problem follows. I'd never heard of that before. But it seems to match. Had no codes the first 300 miles, and then intermittent since. Thanks.

@mikeofree, yeah, I've been thinking about that, but didn't want to drop the money for no effect. Guess I'll try that if the misfire doesn't follow the plug. Still easier than trying to gap valve clearances.

I was pretty damn picky about the valve lash too. I triple checked every valve and torque spec cuz I didn't want deal with any internals once the engine was in the car
Gamil is offline   Reply With Quote
Old 10-25-2019, 08:14 PM   #5
Gamil
Scooby Newbie
 
Member#: 220375
Join Date: Aug 2009
Chapter/Region: MAIC
Location: Philadelphia, PA
Vehicle:
2011 Outback Sport
Blue

Default

No luck with swapping the plugs. Misfire is still on #2 (Pending code had gone away, swapped plugs, drove around pending comes back)

I tested resistances on coil pack.
FSM: resistance between the connectors for #1&2 or #3&4: 11.2kΩ 15%.
Measured:
  • 1&2: 11.18kΩ
  • 3&4: 11.16kΩ

Both well within Spec

So I also measured the cable resistance:
  • 1: FSM: 5.0 - 12.1kΩ
    - Measured: 5.3kΩ
    -
  • 2: FSM: 8.5 - 19.9kΩ
    - Measured: 8.2kΩ
    -
  • 3: FSM: 5.4 - 13.0kΩ
    - Measured: 5.6kΩ
    -
  • 4: FSM: 8.6 - 20.2kΩ
    - Measured: 5.4kΩ

Seems odd, as I've not had a problem on #4. So I swapped the wires between 2 and 4, but still getting P0302.

But, just now I was messing with code scanner, and I noticed that I can trigger the code on demand my turning Air Conditioning on and off.

Steps:
  1. Drive around, Warm up Car
  2. Park and Idle
  3. turn on fan and A/C
  4. leaving the AC switch on, turn off fans
  5. clear codes
  6. toggle fan between off and max quickly 3 times
  7. read codes, and voila, a Pending P0302

This was repeatable 5 times in a row. But, just idling with or without A/C running might take a few minutes to trigger the pending code.
Gamil is offline   Reply With Quote
Old 10-30-2019, 03:01 PM   #6
GEE-OTTO
Scooby Specialist
 
Member#: 201277
Join Date: Jan 2009
Chapter/Region: MAIC
Location: Arlington VA
Vehicle:
2008 08 QSM 5MT LGT
QSM

Default

Check your timing first! Could be off a few teeth, next your crank sensor. Third get the correct plugs, your mod list doesn't necessitate those plugs, get the basic FR5AP-11. It will run with those but when you installed did you set the gap correctly?

Did the machine shop install the cams in the heads or did you? Did you check the injector harness? You said you used a new engine front harness, was it intact?

Since the issue is Cyl #2 that some relief so if you are getting spark to the plug and fuel and its timed correctly could be your crank sensor or the plug is foul etc.
GEE-OTTO is offline   Reply With Quote
Old 11-03-2019, 02:08 PM   #7
Gamil
Scooby Newbie
 
Member#: 220375
Join Date: Aug 2009
Chapter/Region: MAIC
Location: Philadelphia, PA
Vehicle:
2011 Outback Sport
Blue

Default

1. Timing belt is fine. Not my first, I gave the engine several full rotations and checked before droppinwg into the car, and checked it again after the first time I ran it. I've had a skipped tooth before on a phase 1 EJ22, and it was pretty darn noticeable. Not "once in a while I get a misfire code"

2. What is there to check ons the crank sensor? WOuldn't a problematic one produce all kinds of errors?

3.
Quote:
Originally Posted by Gamil View Post
I did gap the plugs today and they all measured fine. But, #2 is slightly sooty. The rest looked perfect (no soot, no oil, no white spots, just brown/grey which the FSM says is the norm)
I'm using a new set of the same NGK Iridiums that I had used for the preceeding 50,000 miles without a single code.

4. Shop intalled the valves, stem seals and retainers. I installed the cams. I Read the FSM procedure 3 times before starting, and then started following it one step at a time. Assembly lube, torque specs and sequence.

5. Why would a brand new harness from dealer not be intact? I was running the engine on the old harness with the O2 sensor and knock sensor connectors taped together until after about 300 miles I started getting a "low voltage" code on the knock sensor. I figured it was because a jerry-rigged connector just wasn't staying together. Once I replaced both knock sensor and harness with brand NEW OEM parts, then I started getting the mis-fire code
Gamil is offline   Reply With Quote
Old 11-05-2019, 04:24 PM   #8
GEE-OTTO
Scooby Specialist
 
Member#: 201277
Join Date: Jan 2009
Chapter/Region: MAIC
Location: Arlington VA
Vehicle:
2008 08 QSM 5MT LGT
QSM

Default

You tell us why the variables are affecting Cylinder two Just throwing out all the basic stuff to look at without being right beside you while its happening No insult or negative connotation just trying to be helpful

If two is coated in carbon/soot have you pulled the injector Cyl 2 and swapped it with another? Ive had a bad injector in a EJ25D and Ej251 do similar, the injector would essentially flood the chamber at anything above idle.

The crank sensor tells the ecu where each cylinder is/position of the crank for firing purposes, can't hurt to diagnose, if you ruled it out no need to worry with it
GEE-OTTO is offline   Reply With Quote
Old 11-05-2019, 08:02 PM   #9
pcampbell
Scooby Specialist
 
Member#: 437670
Join Date: Jan 2016
Location: VT
Vehicle:
2005 2.5 SC OB

Default #2 Misfire after rebuild, 2011 OBS

Valve lash... can you do this correctly on the bench , versus heads installed and timing belt on? I am guessing you did it based on the FSM. The method I see in the FSM has the timing belt installed, I am not sure if it really matters as long as the valves are in the "TDC" position. Did you use the cam pulley arrow (not tick) as your guide for valve lash? Cam pulley Arrow up equals cyl 1 adjustment location.

Probably a long shot but how are your head grounds?

Last edited by pcampbell; 11-07-2019 at 10:45 AM.
pcampbell is offline   Reply With Quote
Old 11-09-2019, 04:05 PM   #10
Gamil
Scooby Newbie
 
Member#: 220375
Join Date: Aug 2009
Chapter/Region: MAIC
Location: Philadelphia, PA
Vehicle:
2011 Outback Sport
Blue

Default

Since it is specific to #2 the cause *should* also be specific to #2. These engines use a wasted spark, which is why I'm hesitant to spend money on a coil pack since #1 has been fine. I would expect the same logic to apply to cam + crank position sensors.

I just checked the lash, and the intake secondary valve had an extra 0.003" (Delta specs it as 0.006, I was almost able to get 0.010" feeler gauge thru). I don't know how significant that really is, but it is specific to #2. The other lashes were solid. All lashes on #4 were also good. So I'm hoping this solves it... Now to put lower the engine back into the mounts and bolt everything back up.... *crossed fingers *
Gamil is offline   Reply With Quote
Old 11-09-2019, 05:48 PM   #11
Gamil
Scooby Newbie
 
Member#: 220375
Join Date: Aug 2009
Chapter/Region: MAIC
Location: Philadelphia, PA
Vehicle:
2011 Outback Sport
Blue

Default

Nope. Still got the pending code very quickly by toggling ventilation on/off quickly.

OTTO, thank you for trying to help. Sorry, I didn't mean to sound annoyed or ungrateful. I just like to understand the logic behind checking something. Tracing the ignition path back makes obvious sense. But the cam/crank position are less obvious to me. I would expect a bad crank sensor to throw all kinds of codes, and a bad cam sensor to have codes for both cylinders. If that's a wrong expectation please educate me.

I'm used to troubleshooting computers, source code and networks. If I have a bad network router, I expect everything on that router to have comms issues, not just one.

pcampbell, ya know a week ago i would've said that I think my grounding is fine. But today, while bolting the exhaust back on, the grounding strap closest to #2 broke. So maybe there's something to that. It must have been corroded enough to not really be doing its job.

As far as valve lash, what really matters is that the cam lobe isn't affecting the rocker arm. that's easy to be sure of when you can see the cam itself. The lines and arrows are external references for when parts are closed up. It cam be more difficult on a bench because putting it in the right position can mean some otherc valve are lifted and thus the heads don't lie flat
Gamil is offline   Reply With Quote
Old 11-10-2019, 04:22 PM   #12
Gamil
Scooby Newbie
 
Member#: 220375
Join Date: Aug 2009
Chapter/Region: MAIC
Location: Philadelphia, PA
Vehicle:
2011 Outback Sport
Blue

Default

- Timing checks out, with both the pulley marks and what's left of the lines printer on the belt.
- Replaced the broken ground strap, no change
Gamil is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -4. The time now is 10:29 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2019 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.