Code p0303, 0304

[subsince77]

Hi all,

 

I have read through the threads on these codes, but I am still not quite sure of my next step. My problem is similar to many others here. 97 OBW, 2.5L, 195000 mi, occasionally giving the CEL, usually while cruising down the highway for a couple of hours, no feeling of missing or stumble, or loss of power. So far it is always these two codes together. This morning it happened after only 15 minutes of driving, I was going down the street about 30 at 3500 RPM. The light flashed for about two or three blocks (that was new) until I shut the car off, then stayed on after I restarted. Again, no hesitation or missing perceptible.

 

I have just, like last week, replaced the wires and plugs with Subaru wires and NGK laser platinums. I have never replaced the ignition coil. Is that the next logical step, and should that also come from Subaru. I only ask because it is a $100 part, so if I should check something else first, I will. And, the nearest Subaru dealer is 150 miles away, so it means travel or buy it online. Just wanted to know if this is my next move.

[beataru]

Well, generally CELs will come on at times like this when the car is not passing emissions. I dont know what the codes are hehe, so I will need to look those up, but it could be as simple as an o2 sensor either unplugged or malfunctioning. And you say the CEL flashed??? When those flash, unless its an obd 1, it means stop now or be sorry.

[2.5GL]

Flashing CEL generally means get of the road, park it, and tow it. Solid light means drive to facility to have checked. The two codes mentioned are misfire Cylinder #3 and #4. Since these two codes coincide with the rear coil operating the #3 & #4 cylinders, the coil pack could be the next logical step.

I would check compression on all cylinders and possibly do a "leak down" test. To do a leak down test, apply compressed air to cylinder while at top dead center a.k.a. TDC, and check for air flowing out of intake manifold, exhaust pipe, oil filler cap, radiator cap. No air flow should be felt or noticed from intake, exhaust, and radiator, but a slight amount from oil filler cap is normal. If air movement is felt from intake or exhaust you might very well have a burned valve, usually on the exhaust side.

 

Lewis

[subsince77]

Thanks, those are good suggestions. I didn't know what the flashing was about. Strange that something could be that wrong and not be able to feel a thing. Yes the codes are misfires on 3 and 4, again, that's why I replaced the plugs and wires last time. After it flashed, I shut it off and parked for about an hour, when I restarted, the light just stayed on steady, After clearing the codes, it did not come back on.

 

For what its worth, when I changed the plugs, every one was perfect color with no sign of oil etc. The car runs very strong, starts perfectly, idles smoothly, does not use oil, and gets 25 mpg in town and 30 on the highway. I have had no indication that anything was wrong until I started getting this code occasionally. I think I'll change the coil out first. Any information on whether it needs to be from Subaru or not?

[GeneralDisorder]

Change the coil - those two cylinders use the same side of the coil (wasted spark, bank fired ignition) so it's a sure bet the coil is on the way out.

 

GD

[garthpro]

I am seeing the same thing on 2k obw with 215k on it. EJ25. only showed up after new Headgasket. could the coil have received undue wear when the overheat occurred? the rebuild was about 190k. and this is the only remnant. Car still runs great tho.

and oh yeah, I got some solid and some flashing! but when I ran it it was just misfire 3 and 4 !

[montana105]

Guys/Gals- does that MPH/RPM sound right in original post? 30 mph@ 3500 rpm,seems high to me and if that's the case with mileage stated wonder if the OP is winding car to high to long,my 93 Leg runs approx 3200 rpm at 75 mph in 5th gear.Don't know my logic here,the mph/rpm stood out though

[subsince77]

Original post was about going a couple of blocks in a small town between stop signs. In second gear 30 mph is just about 3500 RPM. I routinely run this car up passes at between 3700 and 4700 RPM. During an acceleration onto a highway I'll hit 5000 or so. It seems to like that just fine. I don't run all over town in second, but with a 25 or 30 mph speed limit, I don't always go to third between stop signs. On the highway, 3500 in fifth is 75 mph. I think horizontally opposed engines like to spin. Actually, I think the auto tranys on these cars keep them running way too slow most of the time. My problem was an old coilpack. All is well after that change.