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2003 Subaru Outback H6 Wagon
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34 Posts
Discussion Starter #1
Something interesting happend on my last maintenance:

I did an oil change with filter and changed all spark plugs NGK PLFR6A-11. After 2 miles of test drive the engine started to misfire on cylinder 2. I deleted the code and the misfire was gone. On the next day there was a misfire for 2 seconds with no code. On day 3 misfire was all the time there.

What I did:
1- because there was an old entry P0171 (bank one too lean), I changed the O2-Sensor on bank 1 -> misfire still there

Now the mishaps began:
2- I changed the coil with oem on cylinder 4 (it was a long day and I lost the orientation) -> didn't help ;-)
3- Still in the loss of orientation, I switched the plug on cyl 4 to the old one...

Now the mystery begins -> the misfire is gone....

What could have happen here????
 

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Registered
2008 OB Limited 2.5i, Portland OR USA
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5,661 Posts
P0302 is for cylinder #2, not #4. This is driver side, front.
 

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2003 Subaru Outback H6 Wagon
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34 Posts
Discussion Starter #4
@cardoc: I didn't touch the coil and plug from cyl. 2....
@johnre: I know, as I wrote in my post...that's the mystery....

Since the change it seems, that the engine is not running as it should. I'm missing some HP and torque. Sometimes there is a small rough idle.
During the warm up, the AT doesn't shift as smooth as before between 30-40mph.
It is hard to discribe, but I had the phenomenon before, when I bought it. After installing the original muffler it ran as it should.
Tomorrow I'm going to change the sparkplugs again for testing.

...or I'll get schizophrenic in my mid ages....

BTW what had been done before:
Air filter, battery, PCV is new. I checked and cleaned all groundings in the engine bay
 

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Registered
2003 Subaru Outback H6 Wagon
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34 Posts
Discussion Starter #6
I thought I had, but I'll triple it :sneaky:
 

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2003 Subaru Outback H6 Wagon
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34 Posts
Discussion Starter #7
Well I'm finishing my research:

  • changed the spark plugs to another type
  • checked all connections: groundings seem ok (I tested left right and at the starter with the multimeter and cleaned them again on both sides) did I forgot one? - I also cleaned most of the plugs I've found with compressed air - no corrosion at all
  • on coil number 1 (pass side in the front) the plug didn't sit tight anymore, because this plastic "barb" broke of the coil - so I put there the new one
  • to be sure I also changed the O2-Sensor on bank 2
result for know:
I let the engine warm up while idling. The engine isn't reassembled completly.
She started like charm as always.There is still some small amount of rough idle. On the scanner I saw, that the idle is changing within 25-50rpms quite quickly.
The responding of the engine to the pedal is much more better....

During idling I can hear the injector on cylinder 5 ticking (its for sure the injector). You even can feel it. It is not very loud, I think when the brackets and the sound deadening you can't hear it anymore.
Is this an injector problem or an electrical kremlin?
 

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Premium Member
2001 VDC/SC One of a Kind
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13,968 Posts
Without hearing the injectors, can't say.

If the fuel trims aren't crazy and the misfire is gone, then I wouldn't worry about it. Unless it's a loose spark plug. That tends to make a pretty loud tick, kinda like a loose valve.
 

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2003 Subaru Outback H6 Wagon
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34 Posts
Discussion Starter #9
Did the test drive for a couple of miles and its running like it should be :D
When it idles and you go in first gear, you think the engine is shut down, because no noise and vibes. It also seems like that HP and torque are back again, at least 99% before the service.... overall everything smooth again...

I've tried this spark plugs and they predent to be good: Brisk

I made a video which I'll try to upload tomorrow....

What concerns me a bit: there was no loose connection, except on coil nr. 1

@cardoc: Thanx for your support! :cool:
 

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2003 Subaru Outback H6 Wagon
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34 Posts
Discussion Starter #11
Good to know for next time!

Here is the video:


It's the injectors and NOT the valves!
 

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Premium Member
2001 VDC/SC One of a Kind
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13,968 Posts
Sound normal in the video. Could be the recording state.

If it is one injector making more clacking than the others, and it's not the spark plug/coil arcing to the sleeve, then if/when you get a misfire on that cylinder, check the injector, along with the plug and coil.

I've had a few 3.0 and 3.0R engines sound like a valve clacking or a timing tensioner knocking around and it was a loose spark plug. So I reiterate, a loose spark plug will make that noise.
 

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2003 Subaru Outback H6 Wagon
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34 Posts
Discussion Starter #13
Thanx Cordoc,
it's hard to focus with mobile-mic. The video doesn't sound as it is in reality.
Of course all injectors are ticking.... only the one on cylinder 5 is the loudest....as far as I can tell it's no clacking
Until now there is no misfire and the engine is smooth...

I'm going to watch it with healthy quantum of paranoia... o_O
 

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2003 Subaru Outback H6 Wagon
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34 Posts
Discussion Starter #14
Well here we go again...
After 60 miles of driving, the confusing shifting during city limits is back - plus some anoying vibrations, especially after 90° turns with some weight (app. 100lbs) in the back.
Also, the slightly rough idle came back...
And I think I am now also an owner of the jolt by engaging and disengaging the cruise control.....

Is this still a problem with the groundings to the engine?
 

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2003 Subaru Outback H6 Wagon
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34 Posts
Discussion Starter #16
The voltage is fine around 14.5 to 14.6 while driving, battery is new and contacts clean now....
 

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Premium Member
2001 VDC/SC One of a Kind
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13,968 Posts
I believe you should check conductance through the ground cable from the battery post to the lug at the starter bolt and then check conductance to the block, intake manifold lugs, firewall lugs and alternator case. What you describe is generally bad grounding.
 

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2003 Subaru Outback H6 Wagon
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34 Posts
Discussion Starter #18
Hi Cardoc,

sorry for my stupid question, to you mean resistance?

I checked the resistance last time:
  • both groundings left and right (for themself)
  • conductance between passenger fender and engine (with left grounding off)
  • drivers fender to starter grounding
All checks were 0,0 ohm...

I didn't check the starter-battery-grounding, which I'll do...

When I drove yesterday, the H6 felt like an 2.5L and the hesitation with the AT is like, it doesn't know when to shift correctly. For example: Usually when you cruise at 30-35mph it shifts and you go with 1200 rpm. Now it feels like a very nervous "double-shifting",or up-down-up...

Still no DTC-codes....
 

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Premium Member
2001 VDC/SC One of a Kind
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13,968 Posts
Yes, conductance is a resistance measurement.

What you describe in the way the engine and transmission is acting is akin to a bad battery and/or grounding problem.

Think of it this way, when the battery in your phone or laptop/notebook gets low it processes data slower. It's the same with the computers on the car. If the available current is low, due either to the battery output or bad grounds, feedback, processing and output signals are slow and the engine and trans performance drops.

If the battery output is equal to or greater than it's posted CCA and the grounds are good, then you'll need to start looking at and checking various sensors on the car for problems. TPS and ECT would be the first. Fuel module pressure bowl would come next. It cracks or the seal is blown out. Then move on to others.

If you have a laptop or notebook, look in to ROM Raider and a VAG-Com KKL cable. The software is free and the cable can he purchased from eBay for $8-20 USD. This will allow you to record data from the car and post it so I can see what the engine is doing.


You would record the data and upload the file to a site like Google drive or other that would allow access to anyone with the link and post the link to the file on this thread.

Data points would be the following:
AF Correction 1 & 2
AF Sensor Voltage 1 & 2
AF Sensor resistance 1 & 2
MAP
ECT
TPS
RPM
Battery Voltage
Both O2 sensors Voltage
Knock Correction
Ignition Timing
CPC Duty %
Fuel Tank Pressure

If you go this route and you have problems with RR you can post up and we'll work on sorting it out so everything works.
 

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2003 Subaru Outback H6 Wagon
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34 Posts
Discussion Starter #20
Thank you very much,

I know RomRaider and I have a VAG-cable (from my old Audi's) , but until now I couldn't manage to get a connection with RomRaider. The VAG-Software is working smooth. I've installed all the com-drivers, but still it won't work.
So I'm going to get another cable...

Until then I'm going to try to trace the lack of grounding the old way...:geek:

Besides that, I use Car Scanner on my mobile, were I can also make logs. I didn't had time to work out how can export the files.

At least it seems to be a small issue!
 
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