Misfire in #4 code, can't solve

[garthpro]

2k obw

EJ 25

215k miles

 

I replaced the HeadGasket last April, ~9 mos. 190k

also replaced everything else that was looking worn

Had it running great now I keep getting the misfire code. replaced plugs and wires again, NGK pltinum and Belden 7mm

 

So this week I tried the Ignition Coil. same thing.

I can feel a rough spot on acceleration SOMETIMES. that is when the idiot light returned.

[eagleb]

This was happening to my 96 obw before my headgasket went out, I thought it was dirty/sticking valves on cylinder 4, so I had the heads checked out and cleaned, and haven't had the code return since. Maybe try running some techron, clean up the combustion chambers and valves to see if that helps?

[garthpro]

I cleaned everything when I did the rebuild. but I will try again when I get the time

thanks

[nipper]

When was the last time the plugs were changed, and the wires?

 

nipper

[WAWalker]

If you did the head gasket work yourself.

 

What did you set the valve clearance to?

[tcspeer]

If you have changed plugs and wires why not get a set of noid lights and check the injector plugs, that is where I found the misfire on my # 3 cyclinder. Turned out my problem was the E.C.U.

[garthpro]

I did the plugs and wires same as HG, april 07, 190k

then plugs again at 204, NGK platinum

[garthpro]

I had a guy who basically I was helping. I don't think we changed anything, as no upper work was required. so we thought.

heads were flat on check.

but the problem wasn't there immediately, it took a few months

[Cougar]

You may have some carbon buildup causing the problem. I suggest you try try running some Seafoam through the intake while revving the engine to see if that clears things.

[garthpro]

darn. NAPA! I didn't realize/know Belden was a NAPA product. I don't trust NAPA stuff.

But can someone please tell me why the wires, as long as they are somewhat acceptable, same resistance, etc, would cause this issue?

I want to know the answer, just not fix the problem! I could do that by buying a new car.

[Cougar]

Beldon makes quality wiring in my opinion. If the wires you are using are in good shape then I doubt the trouble is coming from them. If you want to prove it you can try swapping the lead with another one and see if the trouble moves with the wire. A bad wire could be damaged by having an intermittent break in it.

[WAWalker]

Just one of my experiances to back up my valve adjustment theory.

 

Because it was after head gasket work, I find it to be relavant to your situation.

 

Had been doing all the maintenance and repairs on one customers car starting at 59,999 miles.

 

Head gaskets had external coolant leak. Dealership blew him off, did not repair.

 

Buy the time the "campaign" letter about the head gasket leak came out, the car was at 97 some thousand miles.

I showed him the letter told him he had better get to the dealer and "ride their a$$" to get them to fix it, as once he reached 100k, all bets would be off.

 

So right around 100k they replaced his head gaskets (both sides) under warranty.

 

He brings his car to me after another 3k miles for a regular oil change, complaining of a rough idle and CEL. Misfire code.

 

I had been doing all the work on this car except the head gasket work. Plugs and wires were new as of the 90k mile service. Had never set a misfire code, had always idle fine.

After checking the car out I told him that the only explanation I could give is that the valves were not adjusted properly during head gasket work. He said he had talked to the dealership and they had told him the problem was either ignition related or something with the valve train.

I told him to go back to the dealer and have them check their work as far as the valve adjustment, as that is part of a head gasket job.

He said "the dealer would never touch his car again", and how much would I charge to check/adjust the valves.

 

Long story short, I got paid to fix the dealers mistake. I adjusted the valves.

 

80K miles later the car is still running like a top.

 

I can't guarantee this is your problem (without looking at your car myself), but I've said it before and will say it again.

Adjustable valves need adjusting.

It should be done at Subarus recommendation of 105k miles and/or any time the heads are removed from the engine and reinstalled.

If not done, and no problems arise as a resault, consider yourself lucky.

[garthpro]

Actually I remembered the switch trick from another job and did that today, swapped 2 to 4. same feel.

so perhaps the valve adjust is the way to go.

any idea what this costs? roughly?

I have never done it.

and should I go to a dealer?

[WAWalker]

Mitchell flate rate time is 1.8 hrs. If anyone quotes you much more over 2hrs. Kindly decline.

Valve cover gaskets, bolt, and spark plug tube seals, $60ish.

 

I personaly think this needs to be done. Most people resist due to cost.

 

But as always it may not be the fix.

[garthpro]

Mitchell flate rate time is 1.8 hrs. If anyone quotes you much more over 2hrs. Kindly decline.

Valve cover gaskets, bolt, and spark plug tube seals, $60ish.

 

I personaly think this needs to be done. Most people resist due to cost.

 

But as always it may not be the fix.

 

I replaced all this stuff when I did the HG. Will it need to be replaced again?

 

again, I don't claim to know this stuff, so if I make a mistake here or call something wrong, please tell me

[WAWalker]

No it probably will not be necessary.

A shop will probably include it in a quote though.

[garthpro]

I just thought of one more thing,

this last time when the light came back on, it was when I started out from a stop light, and I really under accelerated. not paying close attention. I was probably texting :>

I somehow think this little tidbit is an important clue, but the double IPA is flowing so .....

 

I also am getting crappy gas mileage, down around 22 city. way low for me.

[WAWalker]

I just thought of one more thing,

this last time when the light came back on, it was when I started out from a stop light, and I really under accelerated. not paying close attention. I was probably texting :>

I somehow think this little tidbit is an important clue, but the double IPA is flowing so .....

 

I also am getting crappy gas mileage, down around 22 city. way low for me.

 

Any information you can give my contain important clues.

 

The more info the better.

[WAWalker]

Manual transmission or automatic transmission, would be a very helpful peice to the puzzle also.

[garthpro]

Stick

sorry.

[nipper]

I used to work for Blue Streak/Standard motor products. We made our own wires. We would test them against OE, and all the competitors wires. The test was 300 hours at 300 degrees with 100,000 volts runniong through the wires, bent over a 2 inch diameter pipe (SAE Standard test). Beldesn Wires always failed very quickly. With us, when we made our wires, we made sure that they exceeded OE specificcations. Belden seemed to build to a common denominator. Also not all silicon is the same. The Higher the resistivity of the silicon, the thicker it is, and the more expensive it is to make. Also the Silicone can not be contaminated during production. Again this is a cost issue. Cheap wires, lesser materials, less attention to the details.

 

Wires are one of the few places where you get what you pay for.

 

Subarus use a waste spark ignition system. This means that two plugs fire at once. Electricity wants to travel the path of least resistance. If anything is out of balance or mismtached, the electricity will choose that path instead of the spark plug in the cylinder that is ready to fire. Contaminated spark plug insulation is a big problem for almost any iginition system, but even more so with a waste spark

 

Also if the wires are not insulated properly , a voltage can be induced in a wire. This doesnt happen as much as it used to, but is easy to do in a car with ires that run parallel to each other. That is why wire trees are important. They keep the wires away from each other reducing this.

 

http://www.magnecor.com/magnecor1/truth.htm

 

NOw the reason why older wires fail is that the silicon starts to break down. The engine compartment is a very hostile place for almost anything. The Silicon breaks down, and it will creat a path for voltage to leak.

 

nipper

[Cougar]

That is pretty interesting Nipper. The testing you did seems extreme to me. If you made wires that could handle that it is pretty impressive and way beyond what the normal operation would be, voltage wise at least.

[nipper]

That is pretty interesting Nipper. The testing you did seems extreme to me. If you made wires that could handle that it is pretty impressive and way beyond what the normal operation would be, voltage wise at least.

 

Opps checked my notes, it was 50,000 volts. We tested the distrubutor caps at 100K

 

No amperage, but the smell of Ozone was horrible.

 

And yes it hurts like hell.

 

Just tripped over this Ignition 101.

 

http://www.jetav8r.com/Vision/Ignition/CDI.html

[Cougar]

That's a lot of good reading there Nipper.

[OB99W]

[...]Just tripped over this Ignition 101.

 

http://www.jetav8r.com/Vision/Ignition/CDI.html

Yes, Nipper, that link does cover a lot of basic info. Most of it is accurate, but there are a few errors and misconceptions. Some aren't too important (it's "Tesla", not "Teslar", and electromagnetic interference is "EMI", not "EMF", which is electromotive force).

 

Some statements are misleading. An example from the section on point dwell is "The ratio of closed points to open is usually about 3:1.". While that ratio can vary depending on application, it's more typically about 2:1. Under "Common problems with a conventional ignition system are:" is "Timing belt (chain) wears and/or breaks "; well, as we know, that isn't limited by the type of ignition.

 

Still, not a bad article, but I'd suggest reading it with a grain of salt.