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Old 10-18-2010, 06:56 PM   #1
lambsmack
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Default Hesitation, P0301 P0304 codes please help

Car:
2008 impreza outback sport
57,000miles
5-speed
All maintenance done on schedule (fluids, etc.):
Plugs- done 10,000 ago
air filter - twice done


Problem:
Car was bone dry, filled tank completely at local mobil. Then
Noticed a very slight hesitation on the highway on a long trip a few days ago. Hesitation is after letting off, then re applying about 0-20% throttle, there will be 1-3 slight small hesitations. My passenger couldn't even feel it by I could as driver. Stop at dealer, paid $30 to check for codes or bulletins/updates for ecu. No codes present, checked fluid levels, coolant overflow tank level at low line, filled to high line (never topped off or changed yet, was planning to at 60,000). 300 miles later (hesitations continuing intermittently) car throws c.e.l. and blinking cruise light. Scan car, returns P0301 and P0304 codes (cyl. 1 and 4 misfire). Clear codes, drive home. Going out later to see if it trips on 2nd drive cycle.

Background:
Car has used a little bit of oil since about 40,000. Switched to 10w-30 syn. from 5w-30 mobil one syn. Since then consumption has dropped but is still there at <1/2 quart between changes (3,500). I drive alot on the highway 75-90 for 200-300 miles at a time. Most miles on car have been like this. Never thrown a c.e.l. before or had any engine/powertrain issues with the car. Hoping someone has some insight here or has had a similar issue. I have a feeling that the fact it threw p0301 and p0304 does have some meaning here but I am unaware of what that might be.

Got this car through a recall/buyback deal on an old truck, so I don't really have the funds of your average new subaru owner. As such I will likely need to deal with this myself unless there is a chance it is a major power train issue in which case I want to get it done at the dealer immediately b/c the 60,000 cliff is approaching rapidly. Please let me know anything that pops into your head. Thanks alot
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Old 10-18-2010, 09:28 PM   #2
lambsmack
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Update: Car didn't start earlier. Cranked for 3-6 seconds twice and got nothing. Checked fluids, checked connections on battery and ignition. Tried again car started. Checked 02 and A/F sensors with meter and both are in spec. I'm thinking it might be a bad load of gas. Any ideas?
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Old 10-18-2010, 11:34 PM   #3
williaty
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Contaminated gas sounds like the best bet since it happened soon after a fillup. Go get a bottle of StaBil and dump it in, then fill the tank to the top with 93 octane. Run the tank as empty as possible, then refill with normal gas. See if your symptoms persist.

On your oil consumption issue, you're better off running the 5w30 anyway. The 10w30 just means your engine is getting worse wear on startup. 1/2 quart in 3500 miles is damned good for a Subaru. Don't start worrying until your consumption gets to near 1qt/1000mi.
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Old 10-19-2010, 12:11 PM   #4
Subikid90
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Definitely bad gas. I had the same problem in my gf's car using mobile gas after running to 1/8th of a tank. I refuse to use mobile now, and a bunch of other people i know have had similar problems. I fixed the issue with the red bottle of heet and premium gas.
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Old 10-19-2010, 12:51 PM   #5
RaineMan
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I'm gonna go with the others and say crappy gas. Forget the sta-bil or the octane boosters or other "gas treatments"... slug a 99 cent bottle of rubbing alcohol in there and top off with regular gas... that should get any water out of the system.
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Old 10-19-2010, 01:50 PM   #6
formula91
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Quote:
Originally Posted by RaineMan View Post
I'm gonna go with the others and say crappy gas. Forget the sta-bil or the octane boosters or other "gas treatments"... slug a 99 cent bottle of rubbing alcohol in there and top off with regular gas... that should get any water out of the system.
There's more water in rubbing alcohol than isoheet or heet.

Rubbing alcohol is 70%, isoheet is around 90% isopropyl, heet is 90% methyl alcohol.

So I guess it works... but or isoheet is probably better.
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Old 10-19-2010, 05:52 PM   #7
lambsmack
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Thanks alot for reaffirming my hunch. Update though:
Car didnt start on first crank, keyed off tried gain fired up. Still have the hesitation. Seems to happen under back pressure conditions, that is after letting off, then reapplying from 0-20% throttle at highway speeds. Hesitation happens anywhere from 30-90 mph in 3rd-5th gears @1,500-3000 rpm. Car also threw another CEL today with same codes as before P0301 and (I was wrong on title) P0302. This is makes 3 times in 4 days that its thrown the same 2 codes. Ran the tank down after this to reserve, added 1 can heet and filled up with 93. Still has hesitation after 20-30 miles of driving but no CEL yet. Checked plugs today, all are clean no sign of oil/coolant contamination or buildup. My only ideas now are 1-vaccuum leak somewhere, 2-bad gas is still cleaning out, 3-in tank filter is clogged with crap (this could make alot of sense), 4-headgasket (hope not). If anyone has any more ideas id love em. Goin to grab in tank fuel filter tomorrow from subaru. Anyone broken into the tanks on these newer ones?
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Old 10-19-2010, 05:53 PM   #8
lambsmack
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also checked fuel trim, and ratios, all seem normal, and it leans out accordingly when the oil cap is pulled so O2 sensor seems ok.
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Old 10-19-2010, 06:14 PM   #9
ScottStokes
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check fuel pressure and make sure fuel pressure regualator is not bad and letting fuel bleed down. Possibly if car was bone dry you burned up fuel pump. They dont seem to like to pump air for some reason
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Old 10-19-2010, 06:16 PM   #10
ScottStokes
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also check coolant temp sensor is in range. For some reason 3 cars this week have come in the shop with coolant temps reading -40. This is florida -40 doesnt happen here
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Old 10-19-2010, 06:42 PM   #11
lambsmack
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ya weird how those fuel pumps dont like nonfuel. Will check fuel sys. pressure tomorrow, was wondering if theres a schrader somewhere (couldnt find one) or you just bypass the regulator to put the gauge on. Dont think burned out fuel pump, car wasnt dead dry, just towards bottom of reserve maybe a gallon or two of poo sloshin around in the bottom. Pump still primes on accessory(audible), but the 3 starting/cranking issues make me think there might be a flow problem, possibly a bunch of junk in that in tank filter. Gameplan is to check fuel sys pressure, replace in tank fuel filter, oil, coolant, then re asess. Anyone have a better plan lemme know.
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Old 10-19-2010, 06:43 PM   #12
TRH_legacy2k
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I had the same problem until a week ago (except cylinders 2 and 4). Check your plugs / wires. If there's oil in the plug tubes, you might have to replace your valve cover / plug seals.

If so, follow this thread http://www.rs25.com/forums/f105/t512...t-install.html

I used the gasket set from Advance Autoparts. 31 bucks out the door, and an hour of wrench time.

Also, replace the plugs while you're in there, as one or more is probably toast.
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Old 10-19-2010, 07:47 PM   #13
lambsmack
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Plugs and holes were all clean, wires looked ok. Will check connections and test resistance.
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Old 10-19-2010, 10:54 PM   #14
lambsmack
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Also if I have to finally cave and bring by the dealer, how would you approach this in order to minimize the financial toll? Should it be warranty? Im just not interested in bringing it for 3 hours of diag at 100 bucks a pop just to be told its an o2 and I need to pay for all.
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Old 10-20-2010, 09:24 AM   #15
GrundleJuice
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print this conversation out in its entirety, bring it to the dealer and give them the conversation and the car. ask about warranty info/coverage first, specifically if it could be an 02 sensor or another emissions related problem(s). really the best way to get it fixed for sure.
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Old 10-20-2010, 11:22 AM   #16
RaineMan
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Quote:
Originally Posted by formula91 View Post
Rubbing alcohol is 70%, isoheet is around 90% isopropyl, heet is 90% methyl alcohol.

So I guess it works... but or isoheet is probably better.
Been using the rubbing alcohol trick on cars for years... it's cheaper than the "fuel treatments" you get from the parts store and IMO works just as well.
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Old 10-20-2010, 02:44 PM   #17
lambsmack
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sadly it hasnt magically resolved itself. Im through 2 tanks of 93 w/ isoheet so i think fuel is ruled out by now. Threw p0301 and p0302 again today, same codes, 4th time, i think its cycling and theres a fault stuck in the ecu. Going to spray coil today to see if theres any shorts, going to switch ignition wires around to rule out those, other than that im pretty much out of ideas, about to cave and go see the stealership.
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Old 10-20-2010, 05:28 PM   #18
TRH_legacy2k
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Quote:
Originally Posted by lambsmack View Post
sadly it hasnt magically resolved itself. Im through 2 tanks of 93 w/ isoheet so i think fuel is ruled out by now. Threw p0301 and p0302 again today, same codes, 4th time, i think its cycling and theres a fault stuck in the ecu. Going to spray coil today to see if theres any shorts, going to switch ignition wires around to rule out those, other than that im pretty much out of ideas, about to cave and go see the stealership.
Definitely not an expert, but some documentation I have has different resistances quoted for different wires:

Resistance value:
#1 cord: 5.6 10.6
#2 cord: 7.3 13.7
#3 cord: 5.9 11.1
#4 cord: 7.3 13.7

Not sure if this makes a difference at all for your model year, or would hurt the car if you switched them around.
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Old 10-21-2010, 02:23 AM   #19
lambsmack
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SUCCESS!

So after 2 tanks and 3 heet cans, I figured it prolly wasnt bad gas. Started thinking scary thoughts about head gaskets and so forth. Sprayed wires, plugs, coils got nothing (useless practice). Later, was flipping through owner's manual and engine specs, saw firing order is 1-3-2-4 and way-ignition system. Hmmmm... went out and checked coil numbering closely, 3-4 are on bottom coil on opposite sides, and 1-2 on the other. (4x cyl. 1 & 2 misfire) Aha, went to dealer to exchange in tank fuel filter ($80) that was about an hour away from being in the car. Parts man said to check plugs, wires, coils and that they had had some issues with the newer coils. Bought new coil box ($160), went home, pulled wires and boom, #2 socket was blackened, and #2 wire tip was also black. Cleaned wire tip thoroughly, swapped coil, cleared codes. 100 miles and 4 drive cycles later, no problems.

Just wanted to thank you all for your help, on point or not, it all gets you thinking a bit harder. Also, ignition spraying is pretty useless considering they're weather sealed, just pull all the connections and inspect them. Finally keep an eye out for these slight hesitations on part load/throttle with c.e.l. and repetitive consistent cylinder misfires, after all this was a 2008 with 56k and absurdly religious maintenance.
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Old 10-21-2010, 09:53 AM   #20
williaty
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Since you've already had coil pack issues, here's some ways to help prevent it happening again:

1) Take the new coil pack and clean it well. I mean literally scrub it with soap and water (this is even more important if you're starting with a used coilpack). Then cover the OUTSIDE NOT THE CONTACTS with silicone spray.
2) Pack the insides of the sockets (the contacts) with dielectric grease. Completely fill them.
3) Pack the insides of the boots on the wires with dielectric grease. Completely fill them.
4) Push the wires onto the coilpack and grease will squirt out. Clean up the grease with a paper towel as well as possible.

The silicone spray helps prevent dirt and, more importantly, salt from coating the coil pack and conducting electricity between the terminals. The dielectric grease does the same thing. It insulates the contacts from water, oxygen, and salt. This prevents corrosion of the contacts as well as prevents water and salt from letting the contact arc over to ground or another contact.

I've take an ignition system that was "dead" (not firing cyls 1 and 3) and brought it back to life just by doing that. That ignition system has another 45k miles on it since then.
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