2004 Subaru outback H6 3.0.
Link to screenshots of data my ebay managed to get:
imgur.com/a/NllMlpi
All running states labeled, managed to get some data while the car was running well for comparison
My partner called me about 15min from home saying the car had started shaking at idle, I jumped in a rideshare and went to pick her up.
Cel light flashing so I connected my laptop, p0301, ok, missing at idle and seems to smooth out above 2.5k rpm
Last service was done by me 200km ago, Oil, Filter (aftermarket), Air filter, Subaru upper engine cleaner, 4l of ATF and center diff oil.
- Swapped the coils between cyl 1 and 3, no good, and I notice the coil for connector is falling appart. Drive the car home as is.
- Replaced the coil connector, still missing on 1.
- Swap the plugs between 1 and 3, still missing on 1 (Ngk irridium plugs with about 5000km on them).
- Measure 12v between supply and ground and getting a 40ish hz reading on signal cable, pull the plug and it sparks against timing cover.
- Check the injector connector, looks good, 12v and 40ish hz across the pins.
- Replace injector in 1 with 5, notice small leak, replace seals on fuel rail, still missing
- Obd2 shows 30 degrees adv at idle, but dropping as I rev it, and short fuel trims on bank 1 at 32%...
- Spent half a day inspecting every vacuum line, cable tying loose ones and testing for leaks around the intake manifold using a bit of water spray and smoke (cigar). (Will attach logging results showing short ft high while holding at 2000 rpm)
I had just done the headgaskets on this engine about 5000km ago with a full set of genuine subaru seals and updated gaskets, machined heads, all by the book, but at this point I was not ruling them out. Oil looks good, coolant looks nice and green no oil or milk.
Ordered a compression tester, getting;
- 165psi on 1
- 170psi on 3
- 170psi on 4
- 165psi on 2
Subie manual says 180 on the low end for a cranking comp test, does not seem like the end of the world to me for a 17 year old car.
(couldn't bother trying to reach 5 and 6, as they are too far back and not coding)
Read about doing a running comp test, so I put the tester back in and start the engine, results looked good at the time for cyl 1, dont remember them exactly, and this is where things get a bit more interesting.
Compression tester hose ripped inside cyl 1 [img]data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7[/img] dropped the exhaust manifold and opened engine mount bolts, lifted the engine for better access to the cylinder.
After a few hours of swearing and frustration the end of the tester came out, lowered the engine and put the plugs back in, suddenly the misfire is gone!
Test drive a few km and everything is ok.
Take the car to the parts store for some hose clamps to replace a few leaky ones I spotted and its running perfectly, 20km round trip.
Checked Fuel trims on the drive all good 2-3% higher then bank 2. Idle adv sitting at 10-15 degrees.
Get home, replace hose clamp behind the map sensor (had to move it, left hose connected), close the injector cover and bolt air filter box down, turn the car on and the misfire is back!
Ok, this must be an electrical short somewhere? right?
Did lifting the engine wiggle the harness? Re plugging the o2 sensor?
Start probing everything I can think of at the engine bay and checking continuity to the ecm, all the coils look good, injectors are good.
So maybe its a busted VVL solenoid even though the miss is only on one cyl (afr seems off on the whole bank)? I cleaned all the Banjo filters while doing the heads, did not know about all the trouble they caused in subaru's at the time otherwise I would have binned them (binned the bank 2 filter, cant reach bank one with oil filter and cooler in place, will try for that soon).
Take it out test it on battery, make sure its moving freely, test ohms range, all looks good. Put it back in and the miss is gone.
Unplug the solenoid while the car is running to see if it has any effect, the engine bogs and get a cel for the solenoid.
Turn the car off and back on and the misfire is back??
Currently waiting better obd2 cable so I can connect with the Subaru select monitor software.
Getting to the end of my talent as a diy mechanic here and pretty ready to take her to an auto electrician. Lost 2 jobs cause of this pandemic and Melbourne is in lockdown again so I'm doing everything in my power to fix this myself.
Also would rather spend money on a scope than paying someone else to fix (better to have the tool in my kit) so if you think that could be the next step let me know.
Any feedback, ideas or tips as to what I should be checking once I start logging with some better software would be appreciated,
Thanks gang!
