Ok, I have a 2011 outback 2.5 CVT with about 150k. Problem is cylinder 3 & 4 misfires when letting off the throttle. Cruise down the road steady throttle let off throttle and that’s when it misfires. Here is what I have done/checked. New plugs and Subaru coils. New crank sensor, cam sensor, crank sprocket, cam sprocket, checked timing, checked valve lash, compression and leak down were both good, smoked intake, checked for dropped valve guides, new air fuel ratio sensor, new rear o2 sensor, new mass air flow sensor, air filter is good, head gaskets test good, swapped injectors front to back and side to side, checked fuel pressure, updated ecm and tcm with latest Subaru programming, knock sensor, cleaned and relearned throttle body, ran it with no exhaust to make sure it wasn’t plugged, new pcv valve assembly. I work on these cars every day and I have yet to have a misfire that I couldn’t identify the problem pretty quickly. The only time I can get the car not to misfire is with the air fuel sensor unplugged which causes fuel trims to default to about +25% I have combed through hours of data and cannot find the issue. I know I am missing something but I can’t find it. Torque converter maybe shuddering causing the knock sensor to misinterpret a miss? Fuel trims do go a bit lean when letting off throttle but not leaner than another car of same model. Any insight? Anybody run into this before? I have never seen this particular issue and it is driving me insane...
Misfire help
Ebteckx
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Diamond makes the coils for Subaru.
I ddunno if they do anymore as my NGK coils came with the Subaru logo on them and the diamond coil that was in#5 did not have a Subaru logo on it.
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Just joined this community and after reading this thread it appears that it describes the issue I'm having on my wife's 2012 outback 2.5i. MIL comes on in about 30-50 mi. Changed bad alternator, fuel pump, cleaned EGR valve, crank and camshaft position sensors replaced, oil control valves replaced, new spark plugs, coils (denso), O2 sensors (up & downstream), MAF over the past yr and still get the misfires codes (P300-304). They all show as misfiring with the initial cylinder that caused the fault varying between all the cylinders. So not sure if the initial cylinder that fails causes all others to also misfire? Also, sometimes get a P0700 (TCM). Which leads me to another question. If replacing the TCM with a used one does the used TCM need to be programmed? What about the ECM? does it need reprogramming if replaced w/used unit? Going to attempt to log the failure on laptop when it occurs. The freeze data was similar to what someone discussed in an earlier post, so not much help there. Any insight would be great.
I put this up every once in a while on this forum, so it's in a lot of places. I'm going to add it on this thread because all this throwing parts at a car is just a waste of time and expense. Always start with the most basic thing on the car that is also a common denominator to everything on the car. The battery and grounds.
This is an LL Bean with the EZ30D H6. Same concept applies to every single car built in the world.
This is an LL Bean with the EZ30D H6. Same concept applies to every single car built in the world.
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When I first started getting codes one of the first things I tried was swapping around the locations of coils and injectors to see if the codes would follow. Despite any amount of fiddling the codes have always stayed the same - P0303 & P0304.
At one point I swapped all the coils with brand new Spectra Premium coils. Again, no change was noted. I have the Subaru OEM coils in now.
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Cardoc, thanks for the llink. However, the problem still occurs. Is there a way to affect the fuel/air mixture settings in the ECM? I wondering if I have to tweak the settings. At this point don't know what else to try or investigate.
There is a way, but doing that will change the fueling for all 4 cylinders and all you do is make another issue.
Check your knock sensor. You can google it. Subaru knock sensors are identical in operation across the years for the H4.
There's datalogging that may help narrow it down. Rom Raider is free and works on Windows laptops. You would need a Vag-COM KKL cable as an interface between a laptop and the diagnostic connector.
www.romraider.com
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mass airflow sensor died on me...misfired like mad... unplugged it... car ran OK on manifold absolute pressure data.... got new Denso sensor on order
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Cardoc, can't find Tps or Knock sensor. Are they known by another name?
At the end of the video you mention that above 45% throttle it was misfiring again and you were going to do some fueling stuff. What was the final outcome?
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