Cylinder misfires or bad injectors, please post here.

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dealer claimed the valves had 0 clearance. I had a independant shop do a leakdown test, hot and cold, perfect accross the board. Contradicting results, what do to next?

My motor was tore down by cobb this week and the misfire was a burnt valve in cylinder 4

 

This is becoming another real problem on the side fed 05-06 legacy and foresters at or above 100k.

 

 

Good read on possible reasons.......

 

http://allwheeldriveauto.com/seattle-area-subaru-burnt-exhaust-valve/

Fuel (AFR) is probably one of the most critical pieces this whole E2E operation. Not only does it provide the fuel (and air) for combustion, but it also provides appropriate cooling to the combustion chamber and associated valve parts. Rough idle is certainly one indicator that things are not right on the fuel side of the equation.

My saga continues. I had CEL with cylinder 2 misfire. I swapped the fuel injector between cylinders 1&2 (the two easiest to reach). I also cleaned the MAF sensor. Drove about 6 wks with no CEL and a smug grin on my face. Then this week another misfire with heavy AC load. The idle got quite rough and I cleared it only to get another the next day. :-(

 

So now compression and leak test? Local shop ok or must it be done by the dealership? Compression I think I understand but where are the leaks that people are seeing?

 

In a related question how hard should it be to pull out the fuel injectors? My troublesome cylinder 2was all I could manage to pull it out and the other was so tight I had to pry it free with a screwdriver. Then putting them back in I lubed them with fuel and still had to put all my weight into it. There must be a better way. Anyone care to share it with me?

Compression test will check the cylinder on compression stroke to see if it holds around 150lbs (normal). Leakdown would be pumping air into cylinder and see how quick it leaks out to check valves. Just doing compression test would probably be fine.

If you are getting quit a bit of misfires and you have swapped to new injectors or coil packs then i would say its probably valves depending on mileage. My motor and a friend of mine locally both had pistons fine, it was the exhaust valves getting out of spec around 100k or so.

Local shop is fine but use someone you trust.

 

As far as pulling and installing injectors you did it correct. Make sure you use vasoline or something similar as the lube, and make sure you start the car and pull fuel pump fuse and let the car die to relieve fuel pressure.

Having misfire on #1 (w/ CEL). Around 5-5.5k it seems to make misfire noise as well so I haven't driven it more than light throttle anywhere. Drove fine cruising down interstate and around town to get home.

 

Will pull coil and inspect/swap. Plugs have <10k on them. Put seafoam in tank last night. Could hear a very slight misfire at idle for past 15k miles (no CEL, only knock sum increment), but was not able to pinpoint what was going on. This could potentially be the root cause of my low load knock.

My saga continues. I had CEL with cylinder 2 misfire. I swapped the fuel injector between cylinders 1&2 (the two easiest to reach). I also cleaned the MAF sensor. Drove about 6 wks with no CEL and a smug grin on my face. Then this week another misfire with heavy AC load. The idle got quite rough and I cleared it only to get another the next day. :-(

 

So now compression and leak test? Local shop ok or must it be done by the dealership? Compression I think I understand but where are the leaks that people are seeing?

 

In a related question how hard should it be to pull out the fuel injectors? My troublesome cylinder 2was all I could manage to pull it out and the other was so tight I had to pry it free with a screwdriver. Then putting them back in I lubed them with fuel and still had to put all my weight into it. There must be a better way. Anyone care to share it with me?

 

I don't have any help for you, but I will say I've seen the same heavy AC load cause serious idling problems and pop the CEL. Going to diagnose and treat the problem this week.

Subscribed.

 

Got my first P0304 CEL yesterday. I'm going to start logging cylinder roughness. At just over 60K miles, I have to change the plugs anyway. Perfect time for a compression test.

Subscribed.

 

Got my first P0304 CEL yesterday. I'm going to start logging cylinder roughness. At just over 60K miles, I have to change the plugs anyway. Perfect time for a compression test.

 

Get a leakdown as well for peace of mind of the valves.

Getting the engine pulled tomorrow by the dealer as I either have a burnt valve or ring failure. I have been getting a cylinder misfire since about 70k and am at 104k now. I was at 10 psi in cylinder #2. Needless to say, I love this car but this seems to be a common problem and it's a MAJOR one! I won't be buying another Subaru after this I can guarantee you that!

Getting the engine pulled tomorrow by the dealer as I either have a burnt valve or ring failure. I have been getting a cylinder misfire since about 70k and am at 104k now. I was at 10 psi in cylinder #2. Needless to say, I love this car but this seems to be a common problem and it's a MAJOR one! I won't be buying another Subaru after this I can guarantee you that!

 

You drove for 34k with a missfire and now you have severe engine damage, and that's why you won't buy another Subaru?

 

Non of the Subaru dealer's in my area had heard of these issues in my area. My missfire ended up being a faulty injector, which I imagine if you drive long enough is going to do damage.

I should note that I changed the injector and ignition coil during that 34k and the check engine light stayed off for roughly 3,000 miles with each part replacement and came back on again.

I'm not sure what the threshold is for the CEL to trip, but you can have lots of misfires without it actually lighting up. I'm learning a lot from my datalogs. Also noticing a little knock under load, and this is with the stock map. Hmmm....

 

Going in tomorrow to get everything checked out. If all is well (like a bad injector) then time to finally swap that uppipe. Here's hoping.

Update: compression was good, replaced spark plugs. Pulls well, seems to be OK but still logging a few counts of cyl #4 roughness. Not enough to pull the CEL though. Still haven't swapped injectors so that is probably the next order of business.

Having misfire on #1 (w/ CEL). Around 5-5.5k it seems to make misfire noise as well so I haven't driven it more than light throttle anywhere. Drove fine cruising down interstate and around town to get home.

 

Will pull coil and inspect/swap. Plugs have <10k on them. Put seafoam in tank last night. Could hear a very slight misfire at idle for past 15k miles (no CEL, only knock sum increment), but was not able to pinpoint what was going on. This could potentially be the root cause of my low load knock.

 

 

Mine ended up being a cracked spark plug (of course I did this after switching coils and injectors from #1 to #2...). Replaced and working fine!

Subscribed && chiming in to report the same issue - p0303 (misfire on cyl #3) at 70k miles on my 05 wagon. Swapped coils and the misfire code came back for cylinder 3.

 

Looking at replacing the injector next.

^^ check your spark plug for cracking before swapping the coil pack.

^^ check your spark plug for cracking before swapping the coil pack.

 

Oops.. I didn't mention, we did pull/swap the #3 plug with a new one before swapping coils. Looked fine.

 

So today, mechanic pulled & cleaned #1 and 3 injectors, replaced (in reverse position) and everything is now running smoothly, doesn't seem to be missing anymore, for now..

I've been having similar issues. Orignally started last summer assumed it was MAF when the CEL came up. So I unplugged the MAF and the idle smoothed out. After I plugged the MAF back in the CEL cleared itself and car ran smooth for over 5 months. Now CEL is back with same code. Am I still to assume it's the MAF or possible vacuum leak? The idle isn't too rough, but almost stalls on cold starts when turning at low speeds. I checked the T-valve and all lines were good and connected. Reading all these previous has now made me paranoid and I'm about to go to my buddy's shot and have a compression test and leak down test done.

 

My car has slighty over 80k. But this only happens during the summer when its 90+ degrees and/or I'm using the A/C.

What are your similar issues? A misfire code? What codes tripped the CEL?

Does anyone know why having the AC on exacerbates these problems?

extra load

Yup. Parasitic drag from the ac comp making it harder for the engine to turn. So when the engine stumbles due to misfire it drops rpm quicker then without ac.

At idle the ECU has an idle-compensation table that speeds up the engine when the AC compressor clutch engages, ostensibly to keep the alternator running a bit faster and to not allow the idle to dip too low, similar to turning your steering wheel at idle - your engine will speed up. As DR mentioned above, underway it is a parasitic load so it will exacerbate any mis-fires or stumbles that are going on.