Another code P0310 cylinder 1 misfire

[Subaru Bob]

Folks: I have a 2011 Subaru Legacy 3.6 with 60,000 miles that is showing code "P0301 cylinder one misfire" which knocks out the cruise, abs and vehicle Dynamic control. I know there is lots of info on that code online but something puzzles me. Before I jump in and preform the typical check plug/swap coils exercise, I thought I would throw this out for any input that may be available.

 

As I search for online solutions and there are many, invariably it is almost always "cylinder 1 misfire" (as opposed to other cylinders). On my car it happens infrequently (but usually when the wife is driving and she hates seeing the dash light up) and when it does, I clear the code and it is good usually for another 200 miles or so--it doesn't reoccur right away. And it could reoccur on highway driving, shortly after startup or city driving. What makes cylinder 1 the offending cylinder so much more often. Is there something else that triggers that cylinder code other than spark/coil/vacuum that warrants investigation?

 

Any thoughts? Thanks.

[dgoodhue]

Inspect coil #1, if the coil heat sink is expanding from rust, replace the coil.

[Subaru Bob]

UPDATE. I removed cylinder 1 plug and coil. Even though both appeared to be in good condition, I replaced both. However, the result is the same-- code "P0301 cylinder one misfire" which knocks out the cruise, abs and vehicle Dynamic control. On a couple of occasions, the abs and dynamic control indicators lit on the dash but then went out. This leads to believe that something in the abs or dynamic control is triggering the check engine light to set a code. These errors seem to show up when rounding a corner or moderate to hard braking. Is there a way to check the physical operation of those symptoms--ie sensors for example.

[DrD123]

Well - before throwing parts at it, you want to run through the diagnostic procedures - it's often the coil pack, plug, or injector - easiest way to diagnose is to move parts around and see if the misfire follows the parts. Check the harness, particularly the connectors to the coil pack and injector for pin fitment and damage (had a misfire on our old odyssey that ended up being a loose pin to the coil pack) - found it by moving parts around and the misfire stayed on that cylinder (sadly, I checked the connectors, etc. after doing the injector shuffle...) - make sure the coil pack is getting the signal from the ECM, make sure all the harnesses are in good shape, with no broken wires, etc. - ohm out the injector on cylinder 1 (should be between 5 and 20 ohms), check your cam and crank position sensors, the crank sprocket, etc.) - if it's always on cylinder 1, it's probably not a timing issue... anyway - lots of things to try before replacing parts. Unless parts are in rough shape, replacing things just because they might be the cause can get expensive really quick.

[dgoodhue]

Just to make sure, you replaced the front passenger coil and plug, right?

[Subaru Bob]

Thanks dgoodhue. I will follow up. And yes, replaced the front passenger coil and plug.

[Scubaboo]

Can't say why the VDC/ABs etc are acting up, but I would try solving the misfire first and hope it solves everything along with it.

 

As mentioned already, since you've done the coil and plug, maybe swap the injector around to complete the misfire trifecta?

 

Also agree on checking the connectors. My brother discovered one of his misfire causes was a buggered up coil socket from the harness. Socket itself not available from the dealer (comes with the harness, $$$), but a few places sell just the socket thankfully.

[Subaru Bob]

Thanks DrD123 and Scubadoo. I will work on the injectors next. Confirmed today that the coil is getting a signal and firing. Suspect inadequate fuel delivery from injector.

[Subaru Bob]

Silly mistakes can lead to a lot of wasted time and money! When the CEL came on originally, I connected my dollar store scanner to confirm the code for cylinder 1 misfire P0301. I did not realize that you had to push other buttons to check for other codes present. After changing the coil and plug---$$$---and confirming their operation, I decided to connect my laptop based scanner since the problem did not go away. Only then did I discover all passenger side cylinders were registering a code. When driving with the laptop scanner connected, code P0014 would register periodically depending on the driving situation---OCV valve malfunction--exhaust valve variable timing not functioning properly. I could see the exhaust valve variable timing fluctuate widely and not in sync with the driver side. Oddly enough, the engine ran fine during all of this. So my focus is now on the oil flow control solenoid (OCV). Elsewhere on this forum there are excellent details of that problem.

 

Thanks to all that responded, I apologize for getting all headed in the wrong direction.

 

Note to self--chuck the dollar store scanner, always use laptop scanner for diagnosis when CEL is on.

[dgoodhue]

Silly mistakes can lead to a lot of wasted time and money! When the CEL came on originally, I connected my dollar store scanner to confirm the code for cylinder 1 misfire P0301. I did not realize that you had to push other buttons to check for other codes present. After changing the coil and plug---$$$---and confirming their operation, I decided to connect my laptop based scanner since the problem did not go away. Only then did I discover all passenger side cylinders were registering a code. When driving with the laptop scanner connected, code P0014 would register periodically depending on the driving situation---OCV valve malfunction--exhaust valve variable timing not functioning properly. I could see the exhaust valve variable timing fluctuate widely and not in sync with the driver side. Oddly enough, the engine ran fine during all of this. So my focus is now on the oil flow control solenoid (OCV). Elsewhere on this forum there are excellent details of that problem.

 

Thanks to all that responded, I apologize for getting all headed in the wrong direction.

 

Note to self--chuck the dollar store scanner, always use laptop scanner for diagnosis when CEL is on.

 

Mistakes and misdiagnosis happens. Even with buying the coil and plug costs, you are way ahead of paying someone to diagnose and repair your car.

[Scubaboo]

It happens, just think of it as doing some PM work ahead of schedule lol!

 

I saw that AVCS thread you bumped up, looks applicable to what you are experiencing now.

[Subaru Bob]

All good. Followed the instructions in the AVCS thread elsewhere on this forum. Of course the problem had to be the passenger side solenoid--the most difficult to get at, but nevertheless a straight forward job once the shields are removed under the car.