08 Outback Misfire P0301

[samW]

Wife called with the check engine light. I pull out the reader and see it as cylinder 1 misfire p0301. Cleared the code and started it back up.
It idles like a dream, even if I idle it up slowly don't notice the misfire.
Now if I put the car under load or quick hits to the throttle I notice it.
Car has about 149k. I have had it about 1.5 months.
I looked at the coil tower just to see if I could see some tracking. I don't notice any. I even took out some rubbing alcohol and wiped it clean. Didn't help.
Coil looks original but not sure. Wires also not sure. Wires seem pretty flexible. I know that doesn't really mean anything. Just I don't think they are real old. I have not pulled the plugs.
I am thinking about just replacing the plugs and wires. Thoughts?? I also don't want to just throw parts at it either.
I know this car was an corp car. I didn't see on the car fax that the plugs or wires were replaced either.

Thanks in advanced for your help

Sam

[Radar]

My '05 recently had a check engine light. Mechanic found P0303 misfire on cylinder three. He diagnosed as a faulty fuel injector. Interestingly, the car was still running surprisingly well, other than a slight rough idle. I only drove some short distances at 30 MPH and slower after the light came on.

After the fix, the car has more power and idles very smoothly. The deterioration may have been so slow that I didn't notice it. The good news is that the repair was not terribly expensive or time consuming.

My mechanic also said that running a turbo engine hard with a bad injector can lead to damage, so prompt repair is a good idea.

[cardoc]

Fuel, Air and Fire. The three items needed for combustion. One of these three is not correct causing the misfire.

plugs, wires, coil, fuel filter, injector, vacuum leak, loose ground, etc.

Go with what you know is behind schedule or unsure of. At least it gets done and you will know where you are on maintenance. If it stops the miss, good. If not, get out the DVOM for pin testing the sensors and actuators.

[samW]

Originally Posted by cardoc

Fuel, Air and Fire. The three items needed for combustion. One of these three is not correct causing the misfire.

plugs, wires, coil, fuel filter, injector, vacuum leak, loose ground, etc.

Go with what you know is behind schedule or unsure of. At least it gets done and you will know where you are on maintenance. If it stops the miss, good. If not, get out the DVOM for pin testing the sensors and actuators.

Cardoc>
Thanks for the info....
Where on an 08 is the fuel filter. That is one of the things I thought of first. Then I tried finding location and everything I could find was in was in the tank part of the fuel pump

I am going to do the easy one first plugs, wires. I read NGK plugs and go to subaru for wires?? I could do coil but some of the things I hear is they "almost never go bad"

I was told when purchased the air filter was new>will double check

Is there anyway a DIY can check injectors?

Thanks again....Will update.

[cardoc]

Fuel filter is in the tank. A fuel pressure and flow test is necessary to determine clogging or pump issue.

No real process to check the injectors without removing for bench flow testing other than a pin test for resistance. With a scan tool that reads data, watching the AF sensor output and fuel trim learning and correction along with the injector pulse it is possible to isolate a fuel delivery issue.

Being as it is isolated to number 1, I would think it is plug, wire or coil. Injector would be iffy and require testing.

[samW]

Originally Posted by cardoc

Fuel filter is in the tank. A fuel pressure and flow test is necessary to determine clogging or pump issue.

No real process to check the injectors without removing for bench flow testing other than a pin test for resistance. With a scan tool that reads data, watching the AF sensor output and fuel trim learning and correction along with the injector pulse it is possible to isolate a fuel delivery issue.

Being as it is isolated to number 1, I would think it is plug, wire or coil. Injector would be iffy and require testing.

Great thanks...
I have new plugs and going to pick up wires at dealer in a bit.
will update if that fixes the issues.
Sam

[samW]

Originally Posted by samW

Great thanks...
I have new plugs and going to pick up wires at dealer in a bit.
will update if that fixes the issues.
Sam

Well I think I have this fixed.
Plugs in cyl 1 and 4 were really bad. I went ahead and replaced the wires also. I did have a little oil running in and around the were the plug wire sits.
Do you think that will cause the wires to fail? Wires I took off were original. 149 K on the car. Replaced with Subaru wires.

Thanks
Sam

[cardoc]

If you have oil sitting at the plug, plan on valve cover gaskets. Oil well cause a misfire and eventually cause a coil to fail.