I had a p0303 and p0304 that kept popping up. No drivability issues with the car whatsoever. I read that my coil pack or igniter could be bad. So I went ahead and replaced both of these.
Now I have a p0302 code that comes up, misfire on cylinder 2. No more p303 and p0304.
1997 outback with 2.5l
Car has 238k
Head gasket replaced at 118
Timing belt kit at 233
NGK plugs and wires at 200k
Car gets 26-28 mpg on long trips, about 23-24 mixed driving.
Idles fine. No hesitation. Runs smoothly.
I read so where that there could be a bad ground. Is there a picture/diagram that could show me where to check for all the possible grounds?!
I essentially gave up for a while, then for the heck of it scanned the car again. I got misfires in all 4 cylinders! wTF!
Reset it, CEL came back again, but this time just the p0302, cylinder 2 misfire.
I'm thinking I will put back the original coil pack and see what codes come up. Maybe I bought a bad coil pack?
My calve cover gaskets are leaking. Will also fix those and possibly a spark plug if it's oily. (But they have 30k on them. Should last 60k).
you put the laser platinum NGK on, those were what it came with and are the 60,000 plugs,
PFR5B-11
aka
2300
---------
the iridiums will fade a little faster than that
but all the rest are 30,000 plugs at best.
______
and it does sound like you have a repeat coil pack problem,...
___
If you think you got a bad alternator sometime in this car, make sure you get a subaru replacement. (these are really cheap to buy at the dealer, as there was a recall on them, and subaru made a lot more rebuilt ones then they could ever replace.).
and here are some pics of later subaru engines to give you a idea as to where the grounds are hidden. (I wish someone would make a similar caption pic for every engine).
what they do is put it on their meters and give you a print out, and if it fails they try to sell you one of their high priced pieces of junk.
if it is noisy it is probably a internal bearing and such things can fail at any time. (sometimes a long time,...sometimes fast....or so I have been told like 15 years ago when I had a Buick one crapping out with a bad bearing, ....the pro mechanic cupped his hands over the openings easily diagnosing where the harmonic sound from, vs. any other part of the belt system).
Went to oreilly auto parts to check the alternator. They said I have to remove the alternator for them to check it. Oh!! Haha.
In the meantime, I pulled the cylinder 2 wire to Che k for oil inside and saw nothing. Put it back in. Filled my car with chevron instead of Costco gas and reset the light. Didn't come back on until about half a tank, but again I have misfire in all 4 cylinders. No change in drive ability!!! Car runs smooth!!! Arggggg.
So, I guess I will replace original ignition coil and see what happens. Also go ahead and order valve cover gasket set to elimanate that.
When did this start happening?
Before or after the timing belt change?
What brand timing belt kit?
It's not going to be spark plug tube gaskets if there's no oil and it's multiple cylinders like this.
What can cause issues on all 4 clyinders...hmmm.....
1. coil pack - i'd try another one, particularly if the replacement was an aftermarket.
if you still have the old one - just install that - highly unlikely (statistically improbable) you'd have identical symptoms from both units
2. timing tensioner or something else related to the timing belt replacement?
3. fuel related?
4. igniter? i'm not sure the failure mode of those though, purely a guess.
List of events:
1: p0303 and p0304. Changed the pcv valve and the fuel filter and codes went away.
2. Changed the timing belt kit in the meantime with a gates kit. Replaced belt, tensioner, pulleys. Full kit. No problems.
3. P0303 and p0304 came back some time later. It would only come on if I drove over 70mph. If I didn't pass this speed, CEL wouldn't come on. I tried this on a 600-mile road trip.
4. Changed the igniter first with oem used item from eBay. Same codes.
5. Changed the ignition coil with used oem item from eBay. CEL went away for awhile, but then p0302 came on.
6. Cleared codes, and every time p0302 came back by itself. Frustrated, I just tried my best to ignore the light.
7. **** light got the best of me. Read the codes again and said ALL 4 cylinders are misfire: p0301, p0302, p0303, and p0304.
8. Btw, no drive ability issues. No bucking, stalling, loss of mileage.
9. Keep resetting CEL and it alternates between just the p0302 or misfire on all 4. Still no drive ability issues.
There you have it.
Great info, ignoring outliers - this rules out timing gear, igniter, coil, plugs, and wires.
If it does it every single day - I think I'd try filling up with premium gas once - I don't think that would be it but it would be no work. a very minor compression/fueling/timing/carbon build up issue might resolve with higher octane.
Fuel - can you check fuel pressure?
How to test the fuel pressure regulators - those rarely have issues in Subarus so I'm unsure how they work - if there's just one or one per side and how they fail if they do?
Severe carbon build up on the heads?
Valve clearance? That's just uncanny probability but I'm more inclined to wonder given the prior head gasket work -
were the heads resurfaced?
what gasket was used? (namely I'm wondering what thickness it is)
I'd swap in an ECU just because I've got them lying around and it's easy and would rule that out, not because i think it would fix it.
you can use a spray pump bottle with water in it to test your plug wires' integrity. spray a mist of water on the suspect wire while its running and see if it changes the idle or sets a misfire code.(@Adamh)
I am not even sure which wire to suspect... It does not appear to be the plug wires, I've switched them around and the misfire stays on cylinder 2. Maybe it is an O2 sensor or coil pack.
@ Sylvester: you say you got the replacement coil used on ebay...you may have bought a new problem...I would get a new one or a known good one to try on it. Secondly, most gas today is cut with alcohol by 10%, now an unscrupulous fuel dealer or middleman might add a bit more alcohol to a load of gasoline to increase his profit margin. That said you may want to try a quality fuel source to see if there is an improvement. Alcohol has less energy BTU's than gasoline and you get less power out of it.
So I switched my original coil back on the car and have run two tanks of 91-octane chevron gas. I still am getting p0302. I think this is good news (!) because it tells me there's a problem with cylinder 2.
(If you've been following this, you saw that I also got P0303 and p0304 with my original coil pack if I drove over 70mph. Since putting on the original coil, I have not driven over 70 and no p0303 or p0304).
I also recently noticed that when the check engine light comes on, my idle starts to creep up from around 750rpm to 900rpm and then sometimes 1100rpm. What does this mean?? Ugh. I hate this **** light.
I will try the water mist idea on the wire. If that's not the case, should I replace the spark plugs (all4 if I'm going to have to replace cylinder 2!).
Should I replace the alternator anyway because it's really whiny? (I think eagleeye said a faulty alternator can throw random codes).
I don't want to throw money at the car'hoping the problem goes away.
Update: I reset the light and then replaced the alternator with a used one from the junkyard. The CEL stayed off for about 60 miles then popped up again. Argggg!!
BUT!!!!
Then, before I could check the code, the CEL went out all by itself!! Drove the car fora few days with no light. Then I recently drove the car up to Lake Tahoe (around 200 miles) and no CEL. I didn't take it over 75 though. Hope this newish alternator continue to do the trick.
But I've found a pattern...again. Eagleeye please help
The light has come on and off itself within the past 2 weeks. It only comes on after I've driven a considerable distance AND I'm now sitting in traffic, but only if in traffic. Case in point: I drive 200 freeway miles, no traffic, the light will not come on. If I drive 50 miles to a destination and then sit in traffic, the light will come on.
Right before the light comes on, I notice my idle rpm will start to climb from about 750 to 850, then maybe 950 or even 1000rpm. Then BAM, the light comes on. And I swear I can feel the car start to shake just the slightest, like a slight stumble.
So, is there a buildup of heat that is causing this to occur? I keep reading about vacuum leaks; is this a culprit?
Idle air control valve?
Map sensor?
Maf sensor?
I'm throwing out words that I have no idea what they mean, but these are words that keep popping up relating to this car and this problem.
This could be both vacuum and/or fuel pressure related. Vacuum lines that are compromised to not always leak. They can leak after a long heat build up, now the hard hose is plausible and then will leak. They can leak when cold, because they are 2 hard to seal. There could be cracks or tears that only let vacuum pass when they warm and expand.
Both the fuel pressure regulators and the MAP sensor are both intake manifold and vacuum tied. If the vacuum on the fpc is compromised the fuel pressure is off based on the AFR. I am a strong proponent of vacuum line care. I have replaced every single piece of vent, vac, and emission plumbing under Franks blouse.
*if you do the valve covers - check the valve clearance, particularly on cylinder #2
a. vacuum leak? i'd suspect a loose hose or cracked PCV hose -
b. swap #2 plug and wire with one from another cylinder.
if the misfire "moves" then it's the plug or wire.
if the misfire is still #2 you know your plug and wire aren't the cause.
alternately just replace the #2 plug with a new one - since they're annoying to get too on that engine - although #2 isn't that bad.
c. can do the same with that fuel injector as well - swap with one of the other ones and see if the misfire moves.
d. The idle correlation and symptom makes me wonder about the idle air control valve. It's not rare for them to need cleaning/stick/fail....don't know that I've heard of one causing a misfire or how it could primarily be one cyliner.
I changed the alternator and the new one makes no noise. Silent (compared to my old one).
Btw, the check engine light shuts itself off after a few drives ( I counted six trips, or six times turning the car on).
I can check the grounds. The pics offered aren't super clear, but I can try.
I have no idea where to or even how to check for a vacuum leak. What hoses do I check? How many? Searching for vacuum leaks on this site pulls up a lot of mention but nothing specific (unless I'm missing it in the DIY section).
I can change the valve cover gaskets, but how do I check for clearance, and then adjust? That's sounds difficult (but I did the timing belt myself, so I'm confident with time I can figure things out). I have a Haynes manual
I haven't changed the spark plugs or wires because they are halfway through their life (30k on 60k plugs and wires). And I've looked up changing the plugs and they seem like a major PIA, but if it's what has to be done, shouldn't I change out all 4?
I don't want to just throw money and time into something that doesn't get resolved.
Ok, so next steps:
Locate grounds and clean
Locate idle air control valve and check/clean
Locate vacuum hoses (!) and look for cracks?
Swap #2 wire to see if the cel moves.
If that doesn't work, then:
Replace leaky valve cover gaskets
Replace spark plug #2
doubt it's the grounds, I've never seen grounds cause an issue. i've seen Subaru's with 1 or 2 disconnected grounds run perfectly fine. of course it could happen, but it's rare.
valve clearance:
get all the valves closed on the cylinder you want to check.
insert a feeler gauge. 0.010" exhaust and 0.008" intake.
they're really annoying to adjust - google it or get the FSM.
that's why I say just swap plugs or just change that one plug (less work and spark plugs are cheap). it's diagnosis/repair, not maintenance.
for my time/money -I'd just buy a new spark plug and swap #2 with a new one. only have to remove one plug.
if there's no oil in the spark plug tubes then the gaskets wont' fix it.
if you're going to do the valve covers - on the H6 engines the spark plugs are way easier with the valve covers removed because it like doubles the clearance to get at them. given it's similar layout to the EJ25D - I'd think that's going to be the case here too. if so - you might want to replace the plug(s) and VCG's at the same time.
An old-timer trick I heard once to find a vacuum leak is to use a propane torch with the torch head removed down to the orifice. Follow the vacuum lines with the (unlit!) orifice and if the engine revs, it means the propane is getting burned in the engine and you found your leak. I'm not sure if that's still applicable to today's engines. First, though, use your ears, maybe aided by a length of heater hose. Vacuum leaks sometimes hiss audibly.
Changing the plugs is not that hard with the right tools and some practice. I use one 3" extension on a swivel-head 3/8" ratchet, without seating the joints all the way because you need to remove them one at a time. The first one will take a while, the second a fraction of that. Reinstall the plugs using a piece of vacuum hose to start so you don't cross-thread them with the awkward angle.
This seems to be difficult problem. I got it too, P0302. Haven't tried new parts yet, I try to find faulty part first, don't like quessing. Wife just bought the car, so no history information. It's 2006 OB 2.5-4AT.
Spark plugs look like new, Bosch double platinum. No airsparks in wires when applying water mist. I checked valve clearances in 2# and 4# >ok. Cleaned coil pack, no visible cracks or burn marks.
Symptom comes only in idle, or when changing gear at low rpm.
Now I swapped between 2 and 4 plugs and wires but got no codes at test drive, but misfire is heard. I think misfire monitor is not accurate in idle, and in medium-high rpm there is no misfire.