Help a Noob, check out my log please?

Car feels good at speed, starts to misfire in cylinder 4 under 1000 rpms at coast as well at idle. Car idles high (1500-ish) and tries to come down after warm up, but has to go back up after it almost dies under 1000rpm. all vacuum hoses are attached, turbo inlet is in one piece.

 

Mods:

invidia catless Dp

Invidia Q300 CBE

AP stage 2

 

Hopefully somebody will actually help as I'm about ready to take it to subaru (again) and see what they say, I just don't want to pay for whatever BS they pull. last time a change of sparks plugs and injector cleaning helped for a while with rough idle, however, this problem feels different.

 

log is just at idle, i believed i had a torn inlet and would run incredibly lean and cause even worse issues while in boost. Now that the inlet is confirmed to to be within spec, I can get some real 3rd gear pulls if anybody wants to see.

 

 

 

Thanks in advance

Bruce

datalog4.csv

I don't see any fuel trim issues that would cause the car to stall out. If your problem is only at idle - I suggest you add your front O2 to the logging parameters. You should also log roughness on all cylinders.

 

 

Have you had any CELs? Sounds like either an O2, injector or coilpack/sparkplug issue.

Only CEL is misfire in cyl 4. I changed my log parameters to those seen just to see the A/F A-D to see about the inlet. I will go change the parameters and do another log.

 

The spark plugs are from Subaru like I mentioned, and the coil packs have been moved around to check, but that doesn't mean anything. Check back soon for new log.

Here's a log at idle again, with two light revs

Data Log.csv

Oh yeah...#4 is the problem. Your fuel trims are more off then they should be, but not horribly. Your afr at idle is bouncing around a bit too..

 

Misfires are usually a bad injector, plug, coil pack or ringland.

 

I would start by swapping the injector to another cylinder and logging to see if the misfire moves to the relocated injector cylinder. If no change, check the plugs (again). If none of these fix the issue - might be time for compression test.

 

My guess is bad injector.

Thank you! Hopefully you are right, and its just a injector. I'll do alittle experimenting and see what happens. again, I really appreciate it.

Changed the spark plug and it looked good, little to no oil (thank goodness). the wire coil that's inside the rubber boot that goes over the spark plug was a little bent. car runs better now. Thanks Spec B!

 

I don't want to point fingers or anything, but Subaru did change the plugs last time sooo

Great news...hopefully that fixes it.