CEL and misfires

[JohnVT]

I (well, my father in law) have a 97 OBW with 125000 miles. The Check Engine Light came on last week, so we changed the air filter (looked like it's been a while), fuel filter (never changed before), and PCV valve (also never changed). This didn't change the CEL, so I changed the plug wires, and finally today the ignition coil. The plugs were changed a few months ago.

What else can cause this engine (phase i 2.5), to misfire?

Are Bosch Platinum bad for this engine?

[Hondasucks]

it will have to complete 40 warm up cycles w/out misfiring for the light to go off, or something to that effect.. and I think it's gotta do it under a similar condition window.. grrr been too long since EMS gotta dig the boog out...

[JohnVT]

thanks.

The engine is still missing, although according to my wife, who drives it the most, it's not consistent.

I'm just wondering what else can cause missing. I will change the plugs this weekend, BUT I bought Bosch Platinums for it, and now am wondering if that's a good idea. I've seen opinions that I shouldn't use them...?

And the clerk at the auto parts store where I bought the plug wires and ignition coil said it's a BIG mistake to use Bosch, but he didn't have the NGKs he said I should use.

I don't know what brand plugs are in it now, but my father-in-law insists he changed them when we replaced the timing belt a few months ago (ok, just BEFORE winter in VT!).

[Cougar]

I would recommend you get some NGK platinums for the replacement. Bosch plugs have not worked well according to some previous users at least.

 

I would take the car to a place you can have the codes read for free like Auto Zone and see what the code is that may help with finding the problem. I think some folks have had to replace the knock sensor for this kind of problem. Also could be the O2 sensor.

[Ratty2Austin]

when the CEL comes on, the ECU goes into a default mode.. clean your AIC valve (thingy attached to the throttle body) it gets gummed up and can stick.. which can cause it to idle too high, or too low.. and the computer defaults and kills one cyl, (misfire) to keep it from possibly overreving

 

this is what they told me, when I was checking my impreza, having the same problem (misfire) sense it runs fine some of the time...

 

the codes can be reset by computer, but you will have to take it to someone who has a Subaru Select Monitor, or a ODBII scan tool

 

if you can have someone (autozone does this for free) pull the codes, that will help determine the problem

[JohnVT]

thanks for your help.

Can you be more specific about which is the AIC?

[Olnick]

It's usually called IACV. Do a search under IACV or idle air control valve--there's a lot of good info. Good luck.

[JohnVT]

Thanks -

I found it! And when I call it IAC and look in Haynes, I find a lot there too!!

Looks like that's working.

Off to Auto Zone (finally) for codes and NGK plugs.

 

(gee, I was on Oahu last October. It's as hot in VT right now as it was there then, but I want to go back...)

[Olnick]

Yeah, just another beautiful day in paradise! But then Vermont is a gorgeous place too.

 

Aloha!

[JohnVT]

I finally got the code at Advance Auto Parts. It's a P0325. Since I've changed plugs, wires, coil, fuel filter, air filter - it's time to change the knock sensor.

Thanks for all the help.

[JohnVT]

Finally changed the knock sensor Saturday. AND the CEL has been off all weekend! and the car is not missing anymore, at least noticeably.

Of course, at 124K changing wires, coil, etc. wasn't a bad idea, but this did teach me to go read the code FIRST!!

 

Now I've read on this board that the O2 sensor(s) can get 'lazy'?? Don't think I want to go tell father-in-law he needs to spend another $100-200 on parts yet!

 

thanks for all the help.

[Olnick]

JohnVT--at 124k changing the front O2 sensor is probably a good idea. It's really not that difficult. Again, search here on the board--lots of good info. Check out oxygensensors.com for decent prices, and if you don't mind a bit of splicing/soldering you can buy a universal model and save even more. Go for it. And good luck!

[JohnVT]

Hello -

 

not sure if this is a new or related problem!!

2 months since this thread, and now the CEL came back on! Going to get the code at lunch today, but have a couple of observations/questions.

 

Last week the car seemed to miss some on hills, but when we turned the A/C off that stopped, and since it's late in the summer, I just let it go.

This weekend, when we left my father-in-law alone with the car!, he said it 'jumped suddenly, somewhat violently', and the CEL came back on. He tried to reset it (by pulling the battery) but it won't reset. Which is good, I'll go get the code now.

Can a seizing A/C compressor cause this? Didn't hear any belts squeal.

Any hints before I come back with the code?

 

thanks, John

[JohnVT]

hello, this time it's a P0302 "Cylinder 2 Misfire Detected".

 

We also bought some Seafoam. Any other diagnostic help would be greatly appreciated! thanks, John

[Cougar]

Putting the Seafoam in the tank may take of things. If that doesn't do the trick then see if you can swap a plugwire with #2 to see if the problem moves with the wire.

[JohnVT]

thanks -

 

this is the first time I noticed someone say to put the Seafoam in the fuel tank. Others have mentioned using a vacuum line - a ported line on the throttle body, or a vacuum line at the top of the intake manifold (just under the throttle body).

Is one method better? Should I do both? Is there a consensus??!!

[Olnick]

The system I read, and used, was to suck a third of a can into the top end through a vacuum hose, wait 5 or 10 minutes then drive it out (mucho smoke!)

Then pour a third of a can into the fuel tank. Worked for me (I think.)

[JohnVT]

thanks. I sucked in about a third, but let it run. Lots of smoke, but realized I should have let it sit. SO did it again, and let it sit 5 minutes. Still lots of smoke, so hopefully did some good! Put the rest in the tank.

 

Will see what happens when my wife uses it today!!

(and maybe buy another can for my old Saabs! - but that would probably make the oil leaks worse...)

[frag]

thanks. I sucked in about a third, but let it run.

Hi! Could you give some more details? What vac line did you use exactly? Did you just drop it in the can? etc.

Would like to do something similar but am afraid the vac could suck in too much fluid and harm the engine.

TIA

[cookie]

one is really doing the old trick of putting water in the combustion chamber to knock out carbon.

This used to be pretty common in the old days, but I have no done it myself in years.

Any fully ported vacum line will do.

[JohnVT]

see http://www.ultimatesubaru.org/forum/showthread.php?t=23344

 

I used the vacuum port at the bottom of the throttle body, just above the intake manifold. Just stuck a hose in the can and sucked in some...

Seemed to work; my wife's been using the car today and says it's much better.

 

NOW, I just need to take the front off again and change the oil pump o-ring, and change the struts!!

[JohnVT]

so I've changed the PCV, air and fuel filters, plugs, wires, ignition coil - and cleaned the intake twice with sea foam.

 

but the car is still missing some, when warm and doing a slight climb, usually in 5th. sometimes downshifting helps, but not always.

 

guess I should change the O2 sensor? anything else. I have checked vacuum hoses, don't see anything there.

 

thanks