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*only* misfires when car sits for more than one day?


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15 replies to this topic

#1 grossgary

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Posted 19 December 2012 - 01:40 PM

Friend has a 2002 Subaru legacy sedan EJ25, 135,000 miles.

***Only when the car sits for more than a day. He said it never happens if the car is driven daily.

Misfires, apparently quite bad, car is jumpy, won't shift right and the check engine light blinks and then once the car is warmed up it goes away and runs fine. That's how I surmise misfire.

It has only stayed lit consistently once, usually it's always flashing or off.

In some ways I think plugs and wires in others I think it too coincidental that it's always (except once) multiples.

Coil pack?

I always have in my mind that fuel pump cap oring issue bleeding off pressure when the car sits but that also seems far fetched.

#2 naru

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Posted 19 December 2012 - 01:44 PM

Leaky injector.

#3 grossgary

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Posted 19 December 2012 - 01:59 PM

Leaky injector.


have you seen this?

why would one leak cause a multiple cylinder misfire?

#4 Fairtax4me

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Posted 19 December 2012 - 02:29 PM

A lot of times one misfire can feel like multiple misfires. Got codes?
How do the plugs look?
When was the last tune-up?

#5 davebugs

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Posted 19 December 2012 - 03:04 PM

Leaky injector.


I've seen this on other vehicles. But they were mechanical injectors and you could POP test them.

Never seen this with electrical injectors myself.

But the symptoms sure sound like it.

The injectors leak and until it runs out of enough fuel pressure it keeps putting fuel into that cylinder. It fouls the plug until the engine warms up.

It will be curious if this is the cause because I haven't witnessed it in an electrical injector.

#6 naru

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Posted 19 December 2012 - 03:05 PM

have you seen this?

why would one leak cause a multiple cylinder misfire?


MANY times.
More than one leaker or intake valve on the leaker is closed thereby "fllooding" the intake manifold.

Put a pressure gauge on it for proof.

Spark plug from my own recent leaky injector looked the same as the others.

#7 grossgary

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Posted 19 December 2012 - 03:47 PM

Put a pressure gauge on it for proof.

great, thanks naru.
1. where/how do you put a fuel pressure gauge on an EJ engine? I've never had to use my pressure gauge on a Subaru yet.
2. replace the injector or reseal it with new oring/seal?

A lot of times one misfire can feel like multiple misfires. Got codes?

Check engine light only "flashes non-stop" during multiple cylinder misfires so can't be just one.

when it does it - it's after a few days of sitting - and always results in a flashing CEL - every single time - never a constant "normal" check engine light.

seems like those symptoms point to something specific, hopefully naru has it covered and i figure out how to use my fuel pressure gauge on a Subaru.

Edited by grossgary, 19 December 2012 - 03:51 PM.


#8 davebugs

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Posted 19 December 2012 - 03:58 PM

Check engine light only "flashes non-stop" during multiple cylinder misfires so can't be just one.


Gary - I'm not sure this is toally accurate.

My current understanding of the blinking CEL is anything that will hurt the emissions system. Remember the gov't could care less about the engine. It's all the expensive emissions stuff they care about that they force on us.

Now it may flash due to more than I cylinder having missfires thus it thinks you may do emissions harm. Which means what you think may be true, but I'm not sure it's true in the purest sense.

But I don't claim to be an expert.

Just like - it's usually o.k. to keep driving unless the CEL is flashing until you get somewhere convenient.

#9 grossgary

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Posted 19 December 2012 - 05:23 PM

Gary - I'm not sure this is toally accurate.

good call.

multiple cylinder misfires result in a flashing CEL.

but the inverse probably is not always the case though it's the only cause i've ever seen of a flashing CEL - makes sense there are others.

he's going to text me if the code comes back so i can check it.

thanks!

#10 Fairtax4me

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Posted 19 December 2012 - 05:32 PM

Blinking CEL just indicates a current repetitive misfire. Doesn't necessarily mean multiple cylinders are misfiring. It does that to get the average drivers attention in an attempt to alert them to a serious problem that may cause damage to other emissions control systems, mainly the Catalytic converters.

Any CEL means something is amiss that will increase emissions. But like dave said, the only reason we have CELs is because of gummint mandated emissions rules.

#11 Caboobaroo

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Posted 19 December 2012 - 09:06 PM

Blinking CEL just indicates a current repetitive misfire. Doesn't necessarily mean multiple cylinders are misfiring. It does that to get the average drivers attention in an attempt to alert them to a serious problem that may cause damage to other emissions control systems, mainly the Catalytic converters.

Any CEL means something is amiss that will increase emissions. But like dave said, the only reason we have CELs is because of gummint mandated emissions rules.



Yep!

Anyways, has the coil pack been replaced before? Some aftermarket coil packs can have a fitment issue with the electrical plug that comes from the back of the manifold on the passenger side. I had one where I replaced the coil pack with an aftermarket one and it had the same issues. Ended up wiggling the plug after it had warmed up and it started to misfire on me.

Also, have the plugs and wires been checked? Look for traces where an arc might be getting past the boot down on the spark plug. Usually the trace will be noticeable on the porcelain of the plug.

#12 grossgary

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Posted 19 December 2012 - 09:41 PM

Anyways, has the coil pack been replaced before?

Not that I'm aware of. He's had it 30,000 miles and had the headgasket replaced, that's it.

Also, have the plugs and wires been checked?

no, that is what i was leaning on and normally I would replace but for them it's not a good fit to throw part$ at it, be nice to diagnose and with such specific symptoms I thought that might be pointing to something. For instance the fuel issue naru mentioned...

But - I have never checked plugs/wires before, didn't really know visible signs were common enough to make it worth looking for, good to know, thanks russ.

maybe plugs/wires will be my christmas present to them. LOL

Edited by grossgary, 19 December 2012 - 09:44 PM.


#13 davebugs

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Posted 19 December 2012 - 11:07 PM

I switch plug wires and check them put well when off the car.

Then see if the code stays with the same cylinder.

Usually I'll throw some plugs in to rule that out. Sometimes the plug will learn you something.

Plug wires seem more problematic than coil packs. And coil packs almost always throw codes for the opposing cylinder.

#14 Caboobaroo

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Posted 21 December 2012 - 07:01 PM

There could also be corrosion on the terminals of the coil pack that the plug wires snap onto. Either a new coil pack or use some Scotch brite and clean then back to a nice brass color.

#15 Gloyale

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Posted 21 December 2012 - 08:00 PM

Just a guess, but from what I've seen it could be from seeping spark plug tube seals allowing oil into spark plug wells.

Run daily, the oil warms and runs downward.....staying at the bottom, below the ceramic away from the wire connection.

Let it sit, oil wicks up between the ceramic and the rubber sleeve, up to the metal tip, inside the spark plug wire end. Grounds out the spark and causes misfires. This can be excacerbated in cool, moist conditions....where condensation accumulates with the oil. (milkshake mist)

The only times I've seen the flashing CEL have been for water or oil or both in the spark plug wells.

#16 Fairtax4me

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Posted 23 December 2012 - 12:30 PM

I wanna say a set of plugs and wires would fix it right up. I think I'd check the spark plugs for fouling, and make sure no oil is getting in the plug wells.
Spark plug wire resistance can be checked. The FSM should have the specs in it.




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