I have a 98 Impreza 2.2L. It's been running real rough when accelerating, and tonight I got a blinking check engine light, indicating a misfire.

 

This just starting happening last week, when the weather has been warm. I don't know if it's coincidental, but I changed the oil and filter a couple of weeks ago, using Castrol Syntec 5W-30.

 

Is it possible that there's a problem with the oil that's causing the problem?

 

What are the other likely culprits?

Sounds like it might be the coil pact, it is very easy to check it with a multi meter and the directions in the Haynes manuel.

I would take it to a place that can read the codes and then you have something to work with. When I had a flashing check engine it was usually is a misfire when it was real wet here. I unplugged a spark wire or two and plugged them back and it would go away. Soemtimes a plug wire or coil is bad. I have seen others say to replace only with OEM wires also.

 

Good luck!

Thanks for the input, guys. I'l check the codes and take the meter to the ignition coil tomorrow.

Just check the codes first and post them here. And either way when was the last time it had a tuneup and a timing belt change?

 

 

nipper

P0141 - Bad 02 Sensor

P0301 - misfiring on cylinder 1

P0440 - something in the evaporative emissions system.

 

That last one has been there for a while and comes and goes, so I haven't worried about it.

 

I measured the resistances of the ignition coil, and the primary side pins measure less than 1 ohm, while the secondary side measures on the high side of spec, about 13.5K.

 

So, we start with a new ignition coil.

 

I was going to pull the #1 plug to inspect it, but my spark plug socket didn't fit. Should be 5/8", right?

No start with a tuneup.

 

Plugs OE wires fuel filter PCV valve and air filter.

 

Unless you want to throw money away on a coil when what it may be is a bad plug wire. Replace the O2 sensor too (OE front) as that would give us a good baseline

 

 

nipper

Whoops, I was reading wrong. So the ignition coil measures within spec.

 

Btw, the timing belt was changed about 30,000 miles ago

Put you a inline spark checker on that # 1 plug, if you dont have one they can be gotten for around under 5.00 dollars at auto parts store. If you dont have spark in the glass window then change wires with another cyl. and check again.

 

If you still have no fire with different wire you may either have a bad coil or bad spark tester.

 

If you have fire to that cyl. then get you a set of noid light and check to see that you can get the #1 fuel inj. plug to light the noid light. If it dont light then you may need the E.C.U. or computer. If you light the noid light and the spark checker then your problem is probably the injector.

Edited April 25, 200916 yr by tcspeer

Well...

 

Turns out that the electrode was broken off the #1 spark plug, so no wonder it was misfiring. I'm not at all happy about that. The #1 and #2 plugs also looked like they'd been running rich, while the #3 and #4 looked fine.

 

Oh, and the reason why I though my spark plug socket didn't fit was because I could turn it without any resistance. It turns out that the plug wasn't seated snugly, which is making me suspect the other work that was done on this engine before I bought it.

Edited April 26, 200916 yr by eryque

Maybe after you change out the plugs and tighten them the correct way cylinders 1 and 2 will work like they should. Since the plug was loose then the grounding wasn't as good as it should be and now will work better. Always use NGK plugs for best results.

Btw, the timing belt was changed about 30,000 miles ago

 

Can you be sure, in light of the poor workmanship you just found?

 

Don't know your mileage but it might be wise to replace timing belt, check pulleys & tensioner, oil pump, cam & crank seals, maybe replace water pump & thermostat.

 

Good luck.

I guess that's a good point. The car has 116,000 miles, and the engine has around 75,000 miles and the receipt from the engine work says that it was replaced. I'll probably wait until the end of the summer to do all that work so the parts bill doesn't feel like it hurts so much :-)