Chasing a P0301 code down
 

Been chasing this code down a bit. A page or two is discussed here.

https://www.ft86club.com/forums/show...93#post3550793

Starting a new thread since I veered so far off OP's topic of coils after I determined that was not my problem.

I hit ~7k rpm at that last little bit before shifting when making a strong pull and throw the P0301 code for misfire on cylinder one. I've shifted to troubleshooting the fuel system. I confirmed it wasn't a coil by trying a new one.

I've been searching threads and watching youtube. This video has me thinking I have a DI injector issue being it's at the tip top rpm where its DI only.
https://youtu.be/zc8aUxBZlsU

The fix looks easy pulling and cleaning, or replacing the direct injector like a port injector.

But getting to the bloody things and dealing with the DI seals looks like a shop job for me. I'd like to do it, but too busy and no backup commuter.

I'm also looking into the fuel filtration system and not finding any pics. Where is the fuel filter for this car? Quick look has me finding pictures of fuel pumps.

Yup. That's where it is. It's just a sock over the pump intake. Don't bother messing with it. You'd have general fuel starvation issues. These are not the droids you're looking for.

Have you done compression or leakdown tests? May not show anything but just to cover the bases.

After reading the other thread my thoughts are, have you taken a log to see what your mixtures are doing at high rpm? If its injector related I would imagine you would see something there.

My second thought was you said you are stock except for the SC, does that include your exhaust? If so it might be worth inspecting your cat converter. A partially blocked cat might cause a misfire.

Lastly, have you checked the grounding wires for the motor are clean and undamaged? Poor grounds can cause all sort of issues.

And yes the fuel filter is basically a sock on the bottom of the fuel pump.

Yes, stock exhaust. No ability to take a log at this time, tune is HKS tablet tune, just upload and download. Had it done at a shop, read instructions, no logging capability with it. Interested in that moving forward as I would like to have the car tuned after I resolve this issue.

From the basic aspects, need to look at plugs and injectors. The grounding might be a good one, did have work done recently on motor mounts, maybe something loosened up.

The HKS website suggests the tablet can display ECU parameters so that might be an option. If your mixtures are off enough to cause misfires it could be dangerous to your motor so its definitely worth making sure its not the cause.

An ecutek tune from a decent tuner and done in person, on a dyno is, in my opinion, worth the effort for FI.

What work did you have done?

I had the torque solution engine mounts replaced with JDM STI mounts. Shop did this. No problems immediately after either. That was this summer.

I'll go dig up the tablet it came with and have a look. Thanks.

Thanks again for the tip on the HKS tablet Turdinator. There is a car status mode on the HKS flash editor tablet displaying up to 23 parameters. But you only get to view 14 at a time, real time. Cool to watch how the injectors cycle sitting in the driveway. When you rev up, both engage, when you hit and hold an rpm, the port injectors turn off and the DI's run it. Looks like the port injectors are the parallel to the accelerator pump in a carburetor.

Anyhow, nice to look at, but no means to log the data other than recording it on my phone while doing some pulls.

On the what I'm doing front, I'm running injection cleaner at the moment. I ran a tank with it, then added a large bottle of the Gumout product when my low fuel light came on. I drove it back and forth on my commute and logged about 30 miles before I filled up the tank again. I've done a couple smooth pulls up to 7k and it was fine. Then I mashed for a hard pull
and felt it stutter a couple times as it swept through 6-7k rpm. Backed out and just finished my drive. This did not throw a CEL light.

Again, below the hitting up near the RPM limit, the engine runs fine. It's only when giving it all the juice. This does lead me to stay on the cleaning injectors line for a bit more before I run into a shop. Already called my local shop for their cleaning machine cycle that doesn't tear the injectors out and it runs $160. Expect this may be my next step.

If I still have issues after that, I'll be going to my local area tuner shop, Surgeline south of Portland. They're 10 minutes from work. If it ends up on the dyno to troubleshoot, I'll likely have them give it a tune if the issue isn't my engine is about to grenade. If I have something clogged, like my cat, it's not giving the sensors any grief yet. I keep checking my antifreeze for signs of combustion schmutz, nothing there to note either. My startup isn't throwing any smoke/steam of antifreeze or such either. If it a blown head gasket, I have 108k on it, about 28 more than usual subi engines. Haha.

My very recent experience with P301 via blown head gasket is that it misfired the worst upon cold start. I caught it early enough that it still ran fine soon after. Opened it up to find a nice clean combustion chamber. This was not on an FA20 but I still think the symptoms would be similar with it needing time to collect enough water to muck things up for a few seconds.


I don't think it's a head gasket but again, opinions and assholes....

Since this is a boxer engine with difficult access, shop will be the one seeing a clean combustion chamber if we get there.

Oil and radiator caps still show no signs of a leak after a week. Oil cap is about the cleanest one I've had on my subarus come to think of it. And I topped the overflow rad can last week, no change.

The injection cleaner after one tank might be helping as I laid into it a few times yesterday and didn't throw a code or feel any misfire. Drive was mostly just to cycle more of the cleaner and get out with the boy and dog for the summer that won't stop this year. Hagg Lake was pretty quiet before noon yesterday.

I have ecutek and we live in the same area if you want to try to pull some logs.

I haven't read the other thread, but just confirming you've also tried to replace the spark plug(s)?

The droids, missed that. QOTSA is one my favorite bands. Look up Desert Sessions if you don't know of them already. If this is a Star Wars reference, I botched it.

Oops, lost my post.

I'm throwing in the towel and taking it to Surgeline in PDX, OR area. They offered good advice of what to do by swapping parts instead of throwing parts at it if I wanted to do it myself. I really appreciate that. But they are much faster than I am at this work so I'm taking it to them.

They advised coil swap, plug swap and port injector swap for troubleshooting to see if problem follows a component. And stated that is where they would start their troubleshooting. I asked if taking a log would help, they said no. I was a little puzzled, but they said it'll just show us the code, not the signal of what's causing it. So no need for a log, but I sincerely appreciate the offer Poogchomp.

But this service also gets me at the shop to talk some more details of improvements to come. I was thinking of getting a tune up service from them and a new tune on the SC system. And at this mileage, I want to replace the coils and start going for the suspension bits and alignment. I have LCAs in a box ready to go, eccentric bolts are in the front already from a previous alignment. Then I threw this code.

Not bad overall with this car, 108k, with an SC since 85k. This is the very first CEL issue, and it's not an O2 sensor Car's been paid off for a long time, mostly fuel, tires and oil have been the brunt of the cost of ownership now. I'm hoping for a just a plug swap for root cause as antifreeze and oil do not show signs of head gasket issue. I've run 2 tanks of injector cleaning products and no change, same P0301 pulling above 6k. It started at 7k and seems to be slowly creeping down into lower rpm ranges. Maybe the cleaner is just cutting more junk loose, not sure. I wonder if they'll borescope the chamber being we all know a sparkly clean chamber is not a good sign for the wallet.