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Old 11-13-2012, 01:35 PM   #1
gdoggmoney
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2007 Impreza 2.5i
Newport Blue pearl

Default Some tips on fixing misfires and a super smooth idle, as well as oil consumption

I wanted to share a few things I learned chasing down misfires and idle issues in my 07 2.5i .

Here's what made my car run better than new at 70k miles. Some of these things are interconnected. I'll leave it to you to connect the dots.

Obvious: Cylinder #2 spark plug well, or spare oil stash type place. Yes, this one seems to be the worst since the oil fill is above it. It was like adding oil seemed to half fill #2 and 1/2 go into the crankcase. New valve cover gasket, and plug well seals fixed this. I did all 4 just because the fel pro kit was 30$ and "while in there.." Vacuum leaks fixed too! If oil is coming out... air is able to come in.

Not obvious: Spark plug wires from factory tested perfect...... Car had slight misfires at idle and engine rocked -- not enough to slow the crank speed and increment the misfire counter, but enough to feel and visually notice at idle....

Subaru decided NOT to use dielectric in the coil pack recepticle, this causes a few issues. Moisture can get in. Worse, arcing can(read does) happen, and especially when #2 (the one prone to the oil filling the plug hole most) is oil filled, the spark will often arc between the plug end and coil pack. My coil pack was charred inside, as was the plug end there. cleaned both off well, cleaned all 4 coil pack recepticles with folded up sandpaper and compressed air/alcohol. Major difference.

Spark plug wires tested good.... why do NGK wires make the car idle smoother and run better? Something was bad, likely oxidization/degradation of the spark cable internal from years of heat cycling.


How not sensitive is the subaru misfire counter? Well I ripped one of my old plug wires seperating the end on the plug from the actual wire.... I was able to jam it back in and the car ran ok, but missed hard at times... WITH NO MISFIRE COUNTER INCREMENTS.

Not obvious: Subaru uses a MAF... but slips PCV hoses and other things on with no real host clamps, or clamps you could undo with a pinky and thumb then slide off... will these magically not expand under heat and leak vacuum? Of course not.....

Solution? Add hose clamps *EVERYWHERE*. See a spot with no clamp? Add it.

Oil consumption...... This was my experience. My car ate oil, 1qt every 1000 miles or so of mobil 1 5w30. Even after fixing the leaks. Problem? Oil control rings locked into ringlands with carbon, compression may have tested "ok" but it should not eat THIS much oil, even though they do by design..... Fix? Seafoam and carb cleaner. pull the plugs, spray some in the bores while motor is hot and off, rotate motor a few times... repeat, but don't be dumb and spray enough to hydrolock the cylinders or dilute your oil to the point of spinning a bearing or causing damage. I like to do this one before each oil change. You not only burn the carbon off the piston crowns and valve faces (that soaks up your fuel charge AND can cause hotspots/detonation) but done right with the turn it over and spray more in the plug holes, you get the seafoam spray/carb cleaner worked down into the ringlands to break up the carbon locking your piston rings in place.

Up side? less oil consumption, more power and compression, better fuel economy.



Hope this helps some folks who wonder how/why the car is running so strange, rough or just not up on power like it was.

This stuff worked wonders for me.
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Old 11-15-2012, 12:45 AM   #2
subi400
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One quick thing....

Who told you that the M1 5w30 is a good oil to use for a subaru? Unless it is the high mileage one the only other good ones from M1 is the 10w30 and 10w40 high mileage, then the 0w40 and the 5w40.

Start by getting rid of that lousy m1 5w30 and getting a "real" oil that won't let your engine down. My 96 impreza 2.2 burns less oil than your car does and my car has just over 201k miles on it.... I run the rotella T6 5w40.

Not to get going on oil stuff, but stuck oil control rings do happen because one, the wrong oil is being used, and two, the car is not being driven hard enough at times. So, the question is, how do you drive your car?

I have heard good things about the seafoam, but with how many miles my 2.2 has on it, it probably wouldn't be a good idea to try it.... The spark plug and wire thing is interesting as simple checking maintenance can take care of stuff like that
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Old 11-15-2012, 09:16 AM   #3
gdoggmoney
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Hey subi400. We bought the car at 40k used. It had oxidized oil inside of it, a decent coating. I moved it to mobil 1 because it was cheap at costco. I assume the previous owner used some dino oil that was prone to leaving that nice brown layer of oxidized burnt oil on the internals.

Mobil 1 5w30 does seem to turn into water in this car, the same all mobil 1 oils seemed to do in my 3076R 1.8T Jetta.

I had no issues in my Jetta with total 5w40, I was going to give that a try next oil change to see how the EJ253 likes it. I did some searching (GASP SEARCHING WITH A LOW POST COUNT!!! OMG) and it seems you guys prefer the rotella.

The plug wire thing, I actually ripped it myself removing it and then reinstalled it to see what would happen. I thought it was funny I had no misfires but the car would obviously lose spark sometimes and other times have weak combustion events(you could feel it especially near idle), but nothing in the ECU.


I've done marvel mystery oil mixes in super high mileage cars, about 1/2qt and under 3000rpm driving. It does well melting the gunk out, but it does thin the oil some. I usually add 1qt right before an oil change and put around below 3k in this 07 2.5i, it seems to pull the garbage out fast as the oil gets dark quick.
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Old 11-15-2012, 09:24 AM   #4
gdoggmoney
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Newport Blue pearl

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Some other things that rid me of misfires an idle/stumbles: Fuel injector seals & intake manifold gaskets. They just sort of shrivel up and decay at higher mileages from heat cycles.

It seems subaru moved to a cheaper fuel injector seal that only seals against 1 surface, vs the originals that sealed against 2 on the injector tip/face. This required slightly crushing the fuel rail to get a positive seal against vacuum (boo subaru)

While there i added some grimspeed 8mm phenolic spacers, removed the coolant feed to the throttle body and completely removed the EGR system.

Then the NGK BKR5EIX-11's seemed to do better than any other plug I stuffed into the car. Last forever and worth the price.
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Old 11-17-2012, 01:03 AM   #5
subi400
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Quote:
Originally Posted by gdoggmoney View Post
Hey subi400. We bought the car at 40k used. It had oxidized oil inside of it, a decent coating. I moved it to mobil 1 because it was cheap at costco. I assume the previous owner used some dino oil that was prone to leaving that nice brown layer of oxidized burnt oil on the internals.

Mobil 1 5w30 does seem to turn into water in this car, the same all mobil 1 oils seemed to do in my 3076R 1.8T Jetta.

I had no issues in my Jetta with total 5w40, I was going to give that a try next oil change to see how the EJ253 likes it. I did some searching (GASP SEARCHING WITH A LOW POST COUNT!!! OMG) and it seems you guys prefer the rotella.

The plug wire thing, I actually ripped it myself removing it and then reinstalled it to see what would happen. I thought it was funny I had no misfires but the car would obviously lose spark sometimes and other times have weak combustion events(you could feel it especially near idle), but nothing in the ECU.


I've done marvel mystery oil mixes in super high mileage cars, about 1/2qt and under 3000rpm driving. It does well melting the gunk out, but it does thin the oil some. I usually add 1qt right before an oil change and put around below 3k in this 07 2.5i, it seems to pull the garbage out fast as the oil gets dark quick.
Quote:
Originally Posted by gdoggmoney View Post
Some other things that rid me of misfires an idle/stumbles: Fuel injector seals & intake manifold gaskets. They just sort of shrivel up and decay at higher mileages from heat cycles.

It seems subaru moved to a cheaper fuel injector seal that only seals against 1 surface, vs the originals that sealed against 2 on the injector tip/face. This required slightly crushing the fuel rail to get a positive seal against vacuum (boo subaru)

While there i added some grimspeed 8mm phenolic spacers, removed the coolant feed to the throttle body and completely removed the EGR system.

Then the NGK BKR5EIX-11's seemed to do better than any other plug I stuffed into the car. Last forever and worth the price.
That is interesting about what the previous owner did. Either did too long of oil changes or used the wrong oil, or both.... I have a friend here who has used the marvel mystery oil and likes it, just haven't used it myself yet. I have also read about dot lll transmission fluid for like 20 minutes idling can clean out an engine decently then change it right after of course. But, running the correct oil and something that doesn't shear down and has good additives goes a long ways

Try the rotella T6 5w40 but don't be alarmed to see the oil get dark or slightly dirty sooner after a change as this oil does a good job of cleaning stuff.... Any turbo car running a 5w30 is asking for big problems....

Yeah, the spark plug boots can tear so easy.... Just have to be careful that is all. Let us know when you switch to see how it does.
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Old 11-17-2012, 06:36 PM   #6
KelConquer
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Did hose clamps everywhere today, I was missing 2 and the rest were pretty lose with those crappy wire clamps. I'd say my car feels better now but it might all be in my head :P
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Old 11-19-2012, 03:47 AM   #7
subi400
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Quote:
Originally Posted by KelConquer View Post
Did hose clamps everywhere today, I was missing 2 and the rest were pretty lose with those crappy wire clamps. I'd say my car feels better now but it might all be in my head :P
Kind of off topic, but doing regular maintenance like what the OP has been doing since he got his current car goes a long ways. I mean how long does it take to check a few things you know like the oil level, coolant level in the over flow tank a quick look at all 4 tires to see if one is leaking air or whatever.

Do what you can on the simple stuff and don't be like all the other total retards out there that don't check anything for 1000's of miles then wonder why everything breaks at once or their engine dies because of not enough oil in the pan... My mother in-law hadn't checked her oil in her older v6 toyota wagon and was down just a bit over 2 quarts of oil after 3500 miles or so because she is too lazy to get simple valve cover gaskets replaced and told her about it and she acted like no big deal, I'll just have the oil changed.... Some people are soo stupid sometimes.... So, please take care of your car
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Old 11-19-2012, 10:10 AM   #8
gdoggmoney
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Rotella T6. 22$ for 4 quarts at walmart, and it made the motor that much quieter after a change. Even considering the valve adjustment -- even quieter. It sounds almost as quiet as a well running normal inline engine now.
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Old 11-19-2012, 10:48 PM   #9
subi400
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Quote:
Originally Posted by gdoggmoney View Post
Rotella T6. 22$ for 4 quarts at walmart, and it made the motor that much quieter after a change. Even considering the valve adjustment -- even quieter. It sounds almost as quiet as a well running normal inline engine now.
Well done ^^^ One more person who listened to the right advice...yeah!! I would try at least a few 4k oil changes before going a little longer, but get an oil analysis done if you want after your 2nd or 3rd oil change with the T6 to see how it is doing.
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Old 11-20-2012, 09:29 AM   #10
gdoggmoney
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Newport Blue pearl

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Quote:
Originally Posted by KelConquer View Post
Did hose clamps everywhere today, I was missing 2 and the rest were pretty lose with those crappy wire clamps. I'd say my car feels better now but it might all be in my head :P
Nah. It should. Once the bay gets hot and they expand, they leak.
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Old 11-20-2012, 12:23 PM   #11
srikid
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Some good info here. Thanks guys!!
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Old 11-20-2012, 05:33 PM   #12
MJEFF
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Default oil consumption

Quote:
Originally Posted by subi400 View Post
That is interesting about what the previous owner did. Either did too long of oil changes or used the wrong oil, or both.... I have a friend here who has used the marvel mystery oil and likes it, just haven't used it myself yet. I have also read about dot lll transmission fluid for like 20 minutes idling can clean out an engine decently then change it right after of course. But, running the correct oil and something that doesn't shear down and has good additives goes a long ways

Try the rotella T6 5w40 but don't be alarmed to see the oil get dark or slightly dirty sooner after a change as this oil does a good job of cleaning stuff.... Any turbo car running a 5w30 is asking for big problems....

Yeah, the spark plug boots can tear so easy.... Just have to be careful that is all. Let us know when you switch to see how it does.
Lots of top flight engine restorers use marvel to loosen piston and rings that have been setting a long time.
A bike mechanic who cleaned the bores of my old Triumph told me to add a certain amount of marvel oil with the gas on my rebuilt engine, for the first 500miles. Just makes the gas a bit oily enough to help the cyl break in.
I also found another lube that works well on rust and I presume it would be good on rings or care parts in general. Its a WD-40 Specialist for Rust, works like a champ. MJEFF
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