Engine misfiring, what should I do? - Subaru Impreza GC8 & RS Forum & Community: RS25.com

stm25rs · 07-06-2005, 01:37 PM

My car had a check engine light. The 2 codes were p0301 and p0302, which means the cylinder 1 and 2 are misfiring. I had a guy at Advance Auto do the check. He told me that the spark plugs and the wires probably need replacing. Before I went there today I heard a clicking sound coming from the engine so I popped the hood to see if I noticed anything. It was caused by a spark going from the cylinder 1 spark plug wire to a bolt. The advance auto guy recommended starting the car at night and looking for any other sparks.

Do you guys have any suggestions as to what needs to be done/replaced, and what brands I should use if I do replace anything?

stm25rs · 07-06-2005, 02:28 PM

I forgot to mention a couple things. The idle is really rough. Also, after heavy rain, wether or not I drive in it, the CEL flashes and the idle is even rougher. However, a few hours after the rain stops, the CEL doesn't flash; instead it just stays on.

**ayanamieve** · 07-06-2005, 02:34 PM

I had p0303 and p0304. Checked my spark plugs and wires and they were good. So I just cleared the code, but after a month, the CEL came on again. I read in the forums that someone replaced their fuel filter and it cleared their CEL. So I did this cuz you have to replace them every 30k and it was just about time for that, and I haven't gotten a CEL yet. BTW I just replaced the fuel filter last week.

solbey11 · 07-06-2005, 02:43 PM

If you have a spark jumping from the wire to the engine, the spark plug wire is bad. There is either a break in it or the insulation is worn down. Electricity will find the easiest way to ground. Once it jumps across there, that plug is dead. And chances are if that one plug wire is bad, then the rest of them are probably just as old. Either that or your plug gaps are way out of spec. If thats the case the wires may be ok but the plugs are bad. Either way, I would recommend replacing both. Whats the point of changing your oil and not changing the filter? And if your car is mostly stock, I would recommend using Subaru plugs and wires from a dealership. They were designed for your car.

solbey11 · 07-06-2005, 02:46 PM

And the CEL flashing is a really bad thing. That indicates a catalytic converter damaging misfire. You are sending raw fuel into the converter and its probably burning the guts right out of it. Probably in the more humid air, it's easier for the spark to jump between the engine and wire itself.

stm25rs · 07-07-2005, 05:37 PM

I'm going to the beach on saturday for a week, and am gonna be leaving the car with my mechanic. I guess I'll just have him do 60k mile service since its at about 56k now.

RSMoNKeY · 07-11-2005, 08:32 AM

Quote:

Originally Posted by ayanamieve

I had p0303 and p0304. Checked my spark plugs and wires and they were good. So I just cleared the code, but after a month, the CEL came on again. I read in the forums that someone replaced their fuel filter and it cleared their CEL. So I did this cuz you have to replace them every 30k and it was just about time for that, and I haven't gotten a CEL yet. BTW I just replaced the fuel filter last week.

that was me (replaced fuel filter)... i have a CEL now..ugh

07-06-2005, 01:37 PM	#1 (permalink)
stm25rs 3.3L Car: 2001 rs coupe, silver My: Subaru Parts Join Date: Jan 2005 Location: White Hall, MD Trader Rating: (1) Posts: 819	Engine misfiring, what should I do? My car had a check engine light. The 2 codes were p0301 and p0302, which means the cylinder 1 and 2 are misfiring. I had a guy at Advance Auto do the check. He told me that the spark plugs and the wires probably need replacing. Before I went there today I heard a clicking sound coming from the engine so I popped the hood to see if I noticed anything. It was caused by a spark going from the cylinder 1 spark plug wire to a bolt. The advance auto guy recommended starting the car at night and looking for any other sparks. Do you guys have any suggestions as to what needs to be done/replaced, and what brands I should use if I do replace anything?

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07-06-2005, 02:28 PM	#2 (permalink)
stm25rs 3.3L Car: 2001 rs coupe, silver My: Subaru Parts Join Date: Jan 2005 Location: White Hall, MD Trader Rating: (1) Posts: 819	I forgot to mention a couple things. The idle is really rough. Also, after heavy rain, wether or not I drive in it, the CEL flashes and the idle is even rougher. However, a few hours after the rain stops, the CEL doesn't flash; instead it just stays on.

07-06-2005, 02:34 PM	#3 (permalink)
ayanamieve Premium Member Car: 98/05 RSTi Fav Mod: Red RSTi badge My: Subaru Parts Join Date: Sep 2004 Location: Irvine Trader Rating: (3) Posts: 805	I had p0303 and p0304. Checked my spark plugs and wires and they were good. So I just cleared the code, but after a month, the CEL came on again. I read in the forums that someone replaced their fuel filter and it cleared their CEL. So I did this cuz you have to replace them every 30k and it was just about time for that, and I haven't gotten a CEL yet. BTW I just replaced the fuel filter last week.

07-06-2005, 02:43 PM	#4 (permalink)
solbey11 2.5L RS-T My: Subaru Parts Join Date: May 2005 Trader Rating: (20) Posts: 4,196	If you have a spark jumping from the wire to the engine, the spark plug wire is bad. There is either a break in it or the insulation is worn down. Electricity will find the easiest way to ground. Once it jumps across there, that plug is dead. And chances are if that one plug wire is bad, then the rest of them are probably just as old. Either that or your plug gaps are way out of spec. If thats the case the wires may be ok but the plugs are bad. Either way, I would recommend replacing both. Whats the point of changing your oil and not changing the filter? And if your car is mostly stock, I would recommend using Subaru plugs and wires from a dealership. They were designed for your car.

07-06-2005, 02:46 PM	#5 (permalink)
solbey11 2.5L RS-T My: Subaru Parts Join Date: May 2005 Trader Rating: (20) Posts: 4,196	And the CEL flashing is a really bad thing. That indicates a catalytic converter damaging misfire. You are sending raw fuel into the converter and its probably burning the guts right out of it. Probably in the more humid air, it's easier for the spark to jump between the engine and wire itself.

07-07-2005, 05:37 PM	#6 (permalink)
stm25rs 3.3L Car: 2001 rs coupe, silver My: Subaru Parts Join Date: Jan 2005 Location: White Hall, MD Trader Rating: (1) Posts: 819	I'm going to the beach on saturday for a week, and am gonna be leaving the car with my mechanic. I guess I'll just have him do 60k mile service since its at about 56k now.

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