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2002 Outback L.L. Bean, 2001 Outback VDC
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Discussion Starter #1
I have been looking around and haven't seen my direct problem yet.
I have an 02 L.L. Bean OBW 133k.
I'm thinking it has all New NGK plugs, 2000 miles ago.
When its been sitting for a day or so and its less than 50F out it will miss on multiple cylinders i had the codes read 3,5,6 were reporting, my reader is on order so i will know if it is the same cylinders or if it is wandering.
I'm thinking either fuel pressure is low, injectors if it is not wandering or coils.
Any Advice?
 

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03 H6 OBW & 06 WRX Sportwagon
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Is your battery old? I've had odd symptoms similar to yours from a bad cell in the battery.

Also, next time you feel conditions are right for it to show the failure, instead of cranking normally, turn the key to ON, wait 5 seconds or so, turn the key to OFF, then back on, wait 5 seconds, repeat a coupla more times. Each time you do this, the fuel pump should cycle on and pressurize the fuel system. Then ,start the car. If you get the same behavior as before, then it likely is not the fuel pressure.
 

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2002 Outback L.L. Bean, 2001 Outback VDC
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Discussion Starter #3
The battery Is New three weeks ago, I will try that. There is plenty of power to crank the car so I'm leaning away from battery.
 

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2002 Outback L.L. Bean, 2001 Outback VDC
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16 Posts
Discussion Starter #4
Does anyone know what fuel pressures should be after pump, after filter, and after regulator?
 

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2002 Outback L.L. Bean, 2001 Outback VDC
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Discussion Starter #5
Update- Fuel pressure after the filter is hold about 40psi at idle and holding after the engine is shut off at about 35psi. It had maybe one or two misses this morning but not enough to throw a code. Usually it will only miss for about 2 mins, then runs great plenty of power. The plugs are not NGK but are a top quality plug.
This morning the fuel press had bled to zero but soon as the key clicked on pressure went to 40psi or so.
Might be indication that the fuel pump and regulator are ok?
ECU? or sensor?
Also in another post i read about pressure washing the engine causing problems, Mine was throughly washed. I would not expect coils to clean up that fast, Im not sure about injectors though.
 

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Update- Fuel pressure after the filter is hold about 40psi at idle and holding after the engine is shut off at about 35psi. It had maybe one or two misses this morning but not enough to throw a code. Usually it will only miss for about 2 mins, then runs great plenty of power. The plugs are not NGK but are a top quality plug.
This morning the fuel press had bled to zero but soon as the key clicked on pressure went to 40psi or so.
Might be indication that the fuel pump and regulator are ok?
ECU? or sensor?
Also in another post i read about pressure washing the engine causing problems, Mine was throughly washed. I would not expect coils to clean up that fast, Im not sure about injectors though.
This is most likely your issue
"The plugs are not NGK but are a top quality plug."

The subaru engines for some reason are notorious for being extremely picky about the NGK plugs and high quality wires. You don't have those that would be the first place I would start given its easy cheap fix vs fuel systems and other problems.
 

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2002 Outback L.L. Bean, 2001 Outback VDC
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Discussion Starter #7
This is most likely your issue
"The plugs are not NGK but are a top quality plug."

The subaru engines for some reason are notorious for being extremely picky about the NGK plugs and high quality wires. You don't have those that would be the first place I would start given its easy cheap fix vs fuel systems and other problems.
Wouldnt that cause missing all around not just for a minute?
Also is premium recommended for the H6 or not?
I dont have my manual.
 

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The old 3L H6 is highly recommended you run premium fuel especially if your running it where engine temps get up there. Running up climbs - hot outside temps etc. The reason for this is due to the hot spots the 3L develops less stable fuel ie lower octane fuels preignite vs the premium fuels go off at the right time etc.

Cold winter temps and fairly low key driving standard fuel is probably just fine. Summer temps highway use or treking to colorado etc for sore premium fuel to avoid preignition and having the car retard the timing to try and avoid it.

The 2.5's were designed to run on the cheap low octane stuff and your just throwing money away putting the more costly more stable ie higher octane fuel in them.
 

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03 H6 OBW & 06 WRX Sportwagon
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yeah, in 02 pretty sure premium is recomended but, it will run fine on regular. Any improvement with switching may take a few drive cycles to show themselves as the knock sensor would need a while to re-adjust the ignition timing. You 'may' get slightly better mileage and more power. I have always used premium in mine.
 

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2002 Outback L.L. Bean, 2001 Outback VDC
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Discussion Starter #10
Thank you. I will definitly switch back.
Back on the plugs they seem to cause missing all the time while running and idling. Also my car has had 5 fuel filters where my benz with 250k has had none. Are fuel filters really a weak point or are they just easy to install and a dealer favorite? This car used to be dealer serviced and the previous owners may not have known much about cars.
 

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I think there is still an engine temp sensor - nowadays combined physically with the Coolant Gauge sender (used to be aseparate part) , that is used to tell the ECU to boost fuel to a cold engine. Perhaps it is bad?
 

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Thank you. I will definitly switch back.
Back on the plugs they seem to cause missing all the time while running and idling. Also my car has had 5 fuel filters where my benz with 250k has had none. Are fuel filters really a weak point or are they just easy to install and a dealer favorite? This car used to be dealer serviced and the previous owners may not have known much about cars.
Fuel filter life is directly related to how cruddy the fuel your putting into the car is.

Most people in the US who purchase fuel from busy gas stations will never experience a plugged up fuel filter simply due to the high standards placed on fuel quality - and storage to address emissions and fuel contamination of ground water.
 

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2001 VDC/SC One of a Kind
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On the H6, cylinder 1, 3, 5 are passenger side; 2, 4, 6 are driver side. Fuel runs to the passenger side first, then the driver side. The fuel pressure regulator is on the driver side rail at the front and the last thing the fuel travels to before going into the line back to the tank. So, given the misfires are not on the even side, its not a lack of fuel.

The H6 had one type of plug - NGK heat range 6 at about $15-18 each. No wires, coil over plug.

Water in the plug tube may cause a miss, but after a couple hours driving, if it got in, it could evaporate out.

The temperature sensor feeds signals to the ECM, the ECM then distinguishes the trim based on that signal and will run the engine in a manner to warm it up fast.

The misfires, being 2 on one side of the motor and 1 on the opposing side may be vacuum related. There may be a broken vacuum hose. It could also be a bad ground somewhere, most likely place would be the ground anchor on the rear of the intake on the passenger side where two wire looms bolt down. Another cause could be the AF sensors are not heating up causing richer than normal fuel trim which floods the cylinders. A poor MAP sensor signal will also cause misfires and often a no start.

Do you have any mice or rats around? May also want to look for chewed wires.

A scan tool that reads live data would be helpful in this case. Fuel pressure on the rail can be normal, but the injector cycle decides what amount or volume of fuel gets shot into the cylinder. Knowing the fuel trim amount for each side of the motor can narrow down the issue as well as knowing what the AF sensors are sending back to the computer.

.
 

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2002 Outback L.L. Bean, 2001 Outback VDC
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Discussion Starter #15
I have a tool and everything looks pretty normal, every once in awhile there will be a massive change to lean by the ECU like -30%. This am I had missing on 3 and 6 for 5 minutes. fuel trim was +5% on both banks, temperature reading was accurate. i will look for leaks and ground issues.
 

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2002 Outback L.L. Bean, 2001 Outback VDC
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Discussion Starter #16
Will injectors suffer limited flow as in being partially plugged not being able to spray enough for start mixture but be able to handle normal run mixture, or are they usually a complete failure?
 

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03 H6 OBW & 06 WRX Sportwagon
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the ECU reacts so, if anything, an injector is intermittently causing a rich condition, which is detected causing the ECU to pull the system very lean.

Could just as easily be an intermittent MAF or front O2 or loose/bad connection from them.

cardoc may have better insight on that.
 

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2001 VDC/SC One of a Kind
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Back to vacuum leak or bad/loose grounds.

No codes other than misfires on multiple cylinders, which are also opposing sides of the engine are either too much fuel due to misinformation, a vacuum leak, or poor spray from the injectors.

Do the misfires move around? Was 6 missing prior? What's the short term trim when it does it? -30%? Look for a vacuum leak that is throwing off the MAP sensor/TPS relation data to the ECM. You can run the engine at idle and spray an accelerator like brake clean or starter fluid at vacuum connections, base of the injectors, top of the injectors, etc.. Use a thin straw to streamline the spray to specific areas instead of a wide spray pattern. Watching the scan data as you do this, or have a helper, each AF sensor will drop in voltage to a rich mixture when you land on the leak. A leak on either side will effect both sides. Its causes imbalance and on the H6, it can be severe imbalance.

There is a vacuum tube milled inside the heads and opens to the base of the injectors. The heads are connected via 2 hoses and a vacuum pipe that runs through the underside of the intake to connect the two heads. They are at the front of the heads and you will have to remove the injector covers to access them. The two hoses will harden and crack causing a vacuum leak that may change with heat expansion as the hoses may soften some after the engine warms up. The vacuum hoses on the top of the intake in the bowl area in front of the throttle body - same thing; engine heat deterioration and hardening.

If you don't find a vacuum leak, go back to grounds. Also add a full bottle of Sea Foam to a full tank to clean the fuel injectors. If there is any varnish or build up on the tips that effect the patter of the spray, the Sea Foam will dissolve it. Twice a year I add in a full bottle to keep the system clean.

The ECM controls the injector pulse based on math calculations using information from various sensors. When you get this type of misfire, the computer is doing all it can to keep the engine running and balance it at the same time. Low MAP readings means more fuel, but if the throttle is closed, it is starved for air to match the fuel and misses due to flooding of the cylinder. The AF sensors are telling the computer that its running too rich, but the computer is trying to balance the motor with the information its getting from the MAP and TPS combined with CKP and CMP data.

.

.
 

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2002 Outback L.L. Bean, 2001 Outback VDC
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Discussion Starter #19
I was looking yesterday for a vacume leak, Havent found one yet. Plan to change the ECT sensor. I only get -30% while driving. When it is missing its usually +5% to +9%. My scan tool does not show the AF sensors im assuming these are also called o2 sensors. I am very cautious above sea foam, It does exactly what its supposed to but the usually causes me alot of issues on motorcycles. The miss fires are not moving from 3 and 6 but, 1 and 5 have also been involved but are not usually.
 

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2002 Outback L.L. Bean, 2001 Outback VDC
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Discussion Starter #20
I just bought this car 1 month ago but, no miss was noticed or mentioned before.

Is the H6 ECT part number different from H4, and can i get an OEM part number if anyone knows it?
 
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