Irregular Misfire Mystery

Story Time:

I bought my car from a dealer about 2 years ago with around 90k on it (123k now). During the test drive the car seemed fine, but the day I went to purchase it I was informed they needed to keep the car long because there was a misfire in one of the cylinders. A few hours later the dealership got back to me and said it was a timing issue but was corrected and the code was cleared.

Fast forward to my first oil change (I do them myself), shortly afterwards my car starts to bog down a lot and near stalls out while driving, then the check engine light pops on. I read it using a scanner at the local parts shop and it says there's a misfire in the 4th cylinder (I think 4th). I change out the spark plugs with Autolite junk (foolish I guess) and the problem stops and doesn't kick in again.

A few months later I'm driving a really short distance and the car totally bogs out like I've never had a car. It felt like I was driving on one cylinder, the car would barely drive 10mph and was struggling. I quickly pulled into a parking lot and shut the car off. Check engine light on again. Turn the car back on a few minutes later... it's as if nothings happened. I'll note this is a nice sunny day too and I was driving about 30mph when it did this.

So I go back to the auto parts store (same code as before), get more plugs, replace them all, and drive again. No more issues for a few months. I think this rinses and repeats another 2 more times over the next couple of months. Last misfire was a day after I put new plugs in.

I finally think "Hey maybe this is an issue that's serious and needs a mechanic to look at" . I take it to a well respected shop nearby and they give me the car back two days late with NGK plugs in it, telling me I'm an absolute idiot and to never buy Autolite again. They also wrote a 3 and 4 on the coil packs and switched them so I could later decide if it was a bad coil pack I could easily change that out. I'm charged about $280 for this, which sorta bummed me out.

A while goes by, the car I still think feels weak to drive, and eventually the misfire happens again. And again. And Again. I haven't changed the spark plugs because at this point I'm really not thinking it's them. I'm guessing next it might be fuel injectors, but I'm not sure what my best recourse is for those. Should I change them out with new/remanufactured ones myself? Should I go to a mechanic and get one of those $200 fuel injector cleaner services done? Use Seafoam through my vacuum line? I've had literally no experience with solving this kind of an issue before. On my older cars usually a swap of plugs and/or wires would always fix the issue. I'll note too I've ran a bunch of different gas tank mechanic-in-a-bottle fuel injector cleaners through the car too (Techron, Seafoam, Etc) on an empty tank. I sorta wanna try running Seafoam straight through my vacuum line but I don't know what one to use or how to locate it. Or I guess should I take it back to the dealership and have those mechanics look at it?

I hope someone on here has ran into something like this or has an idea of what my next steps on tracing the issue might be. I'm frustrated and the car runs really great besides the fact it seems to be running a little weak and really occasionally has the misfires.

On this last time it happened did you get a code?

Sounds like a coil going bad.

I'm curious, did you ever inspect the spark plugs for possible fuel contamination? Or did you ever notice if the plugs were burned?

The code it's throwing is always P0304 (Cylinder 4 Misfire) even after switching coil packs 3+4 it's tripped this code twice now (which is why I'm debating on trying a new fuel injector).

As for inspecting the spark plugs... I haven't checked them lately (I will over my weekend), but last time a few of them (especially 2,3,4) were pretty fouled/black. I think last time I looked into it that it's possible I have a bad seal of some sort? It's been awhile since I've messed with it... This happened pretty quick after changing the plugs too, like within a few hundred miles. After the mechanic charged me 280 to replace the plugs I quit looking at them.

- - - Updated - - -

Another weird thing... that I'm not sure has relevance or not, it almost always has this issues in the 2-3k rpm range. If I'm driving and only press on the pedal a little so it floats in that RPM range it triggers the misfire more often then other driving times.

Also wondering, could my Cold Air Intake have anything to do with this? I bough the car with an Injen CIT in it already. I don't know if it was professionally installed or anything. It appears to be connected to my electrical as well. Is this something that requires some ECU changes or anything? Just wondering if it's running lean or something from it.

Quote:

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Originally Posted by mcshinigami

The code it's throwing is always P0304 (Cylinder 4 Misfire) even after switching coil packs 3+4 it's tripped this code twice now (which is why I'm debating on trying a new fuel injector).

As for inspecting the spark plugs... I haven't checked them lately (I will over my weekend), but last time a few of them (especially 2,3,4) were pretty fouled/black. I think last time I looked into it that it's possible I have a bad seal of some sort? It's been awhile since I've messed with it... This happened pretty quick after changing the plugs too, like within a few hundred miles. After the mechanic charged me 280 to replace the plugs I quit looking at them.

- - - Updated - - -

Another weird thing... that I'm not sure has relevance or not, it almost always has this issues in the 2-3k rpm range. If I'm driving and only press on the pedal a little so it floats in that RPM range it triggers the misfire more often then other driving times.

Also wondering, could my Cold Air Intake have anything to do with this? I bough the car with an Injen CIT in it already. I don't know if it was professionally installed or anything. It appears to be connected to my electrical as well. Is this something that requires some ECU changes or anything? Just wondering if it's running lean or something from it.

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Your CAI is fine. Like said above, pull the plugs and look at them. If the valve cover is leaking along with the rings on the spark plug tubes, you can keep replacing the plugs, they will always fail sooner or later. The seals are super easy / inexpensive to do on the I4 anyways, hardest part is to carve out the old one if it's baked in there. For plugs always use NGK or DENSO on these cars.

Also for diagnosing purposes before you start throwing parts at it, I would swap injectors and see if the code follows. So take injector 4 and swap it with let's say injector 6. Let the code come back and see if it follows that cylinder 4 injector. Also, I've seen this on a lot of v6 Hondas but check compression and make sure the piston rings aren't blown, highly unlikely but it's worth a try.

Quote:

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Originally Posted by mcshinigami

The code it's throwing is always P0304 (Cylinder 4 Misfire) even after switching coil packs 3+4 it's tripped this code twice now (which is why I'm debating on trying a new fuel injector).

As for inspecting the spark plugs... I haven't checked them lately (I will over my weekend), but last time a few of them (especially 2,3,4) were pretty fouled/black. I think last time I looked into it that it's possible I have a bad seal of some sort? It's been awhile since I've messed with it... This happened pretty quick after changing the plugs too, like within a few hundred miles. After the mechanic charged me 280 to replace the plugs I quit looking at them.

- - - Updated - - -

Another weird thing... that I'm not sure has relevance or not, it almost always has this issues in the 2-3k rpm range. If I'm driving and only press on the pedal a little so it floats in that RPM range it triggers the misfire more often then other driving times.

Also wondering, could my Cold Air Intake have anything to do with this? I bough the car with an Injen CIT in it already. I don't know if it was professionally installed or anything. It appears to be connected to my electrical as well. Is this something that requires some ECU changes or anything? Just wondering if it's running lean or something from it.

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Do you have access to a datalogger? If so, you can install it on the car, and drive it around for a day or so and see precisely what the car is doing at 2k to 3k RPM. Don't forget also, it may not be a part per se, it could be the wiring itself.

I haven't switched the fuel injectors yet. I'm actually not really sure how to do that properly. (Tools needed, fuel pressure lowered?, etc.) I have a 4 Cylinder

Also, no access to a datalogger. I looked at the wiring today as much as I could see and everything looks really new and clean. It's mostly wrapped up in tape though along the fuel rail I think it's called (along the fuel injects taped on a flat bar above them). As seen here: http://i.imgur.com/WLscytG.jpg

To update: Before work I really quickly pulled out the 4th coil pack (technically the 3rd in the 4th's spot) and it was dripping with what I assume to be oil. Here's a pic: http://i.imgur.com/jlIWGnr.jpg

The spark plug looked like this: http://i.imgur.com/5XrO6js.jpg

And the 3rd coil pack looked similar to the 4th: http://i.imgur.com/EWswyRE.jpg

The 1st and 2nd were clean and dry, aside from the red residue on the tip area which I'm assuming is normal from age and it's location? I didn't have time to pull the plugs in any other cylinder as the damned rubber part kept sticking to the spark plug socket and I didn't have the time to waste playing around with it on the other plugs. This is pretty much par for the course with this issue though and from past experience the plugs look shitty to better going in order from 4-1.

The problem was is that last time I changed out the plugs and cleaned off the oil from the coil pack the check engine light clicked on really quick after and when I took it to the mechanic they didn't see the oil and pretty much said I was wrong about it being oil and that all I needed was spark plugs. This is endless frustrating to me as I feel like my car is lamer then it should be (not that it's super awesome or anything) and there's so many variables as to what could be causing it. I've read wires, gaskets, spark plugs, timing, airflow, compression, cylinder ring size, and even overtightened brakes could cause these issues. It's insane. I'm sorta figuring out why the last owner traded the vehicle in...

I guess I'll look into what it takes to switch around the 3rd and 4th injectors (thought I read something about needing a tool to remove them safely and doing something with the fuel pressure) and then maybe look into a new crankcase gasket? It's even more frustrating to switch stuff around because sometimes the issue won't even trip the check engine light for months. I think it has been 5 months since the last time it went off.

Also, this is sorta random, but the issue used to happen (and technically just did again), right after oil changes. Any chance it's because there's a leak and the fresh oil is thin and leaking through the leaks into that area causing the misfire? I suggested this to the mechanic and he thought I was nuts so maybe it's silly to even ask here.

Also I read that putting Seafoam in the Brake Booster line can help burn a lot of carbon out (plus it sounds fun). I'm gonna change out the plugs before I drive to MT from WA so I thought it'd be a good time to do this. To add to my list of questions for you fine folks, where is my brake booster line or a line that feeds all 4 cylinders or how do I find that said line? Thanks

I would say replace your spark plug seals since it needs to be done anyways. Brake booster line is the big rubber hose by your brake master cylinder. ive used seafoam a few times and I cant say its worked or not but it has removed an egr code temporarily til I actually cleaned my egr. about switching the fuel injectors, its pretty easy, just some simple ratchet tools. don't remember but I think I probably just used a 10mm or 12mm to pull the fuel rail and all you have to do is swap the injectors. tbh I really think its just your spark plug seal. That's a lot of oil on the coil pack boot. hopefully that cheap fix will do it for you.

Quote:

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Originally Posted by mcshinigami

I haven't switched the fuel injectors yet. I'm actually not really sure how to do that properly. (Tools needed, fuel pressure lowered?, etc.) I have a 4 Cylinder

Also, this is sorta random, but the issue used to happen (and technically just did again), right after oil changes. Any chance it's because there's a leak and the fresh oil is thin and leaking through the leaks into that area causing the misfire? I suggested this to the mechanic and he thought I was nuts so maybe it's silly to even ask here.

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I suggest you download the FSM, everything you ever wanted to know is in there as far as how to do things. Otherwise you pull the relay for the fuel pump, try to start the car a couple times, this relieves pressure in the line. Than unclip the injectors, and unbolt the rail.

You see the issue more after an oil change because your oil is leaking, but when you do a change you put the right amount back in there again -> more intense leak for a short time. Change the the o-seals on the tube and the valve cover gasket if your doing plugs again anyways. It's an easy and cheap fix to start with, it's a quite normal issue on these cars at this age (as I'm sure on many others too).

Here you go, Felpro part No. VS 50562 R, $23, less whatever coupon you can google right now.
http://shop.advanceautoparts.com/p/f...e+cover+gasket

I've been meaning to get the FSM but every time I go to download it there's an error. I'll try again tomorrow because all this work I've been doing on the car lately would be helped a lot by it.

I'll try the gasket, looks like NAPA by me has them for 17 even. I'll attempt to Seafoam for the hell of it (there's an extra can in my car. They were on sale the other day), and then drop new plugs in.

Hopefully I can report good news, though the issue is so intermittent I might not know.

Thanks for all the help, I'm really loving this forum.

So the Service Manual here..the link doesn't work. I tried googling and that wasn't helpful either. Any ideas of where I can go to get this? I love how well loved the 9g is on the internet...har har...

It's for the 3g, but what you need is in there: http://tearstone.com/factory-service-manuals/

Ha, funny. I buy parts for those, but never thought to use the FSM for them. Thanks for the link!

Replaced the gasket today and degreased the top cover and cleaned stuff up while I was at it. The 3rd and 4th cylinder seals were way jacked up. Hard as rocks and warped into an oval. The car has a lot less hesitation now. Time will tell, but so far so good. I'll throw next plugs in in a few weeks before the trip.

To add an additional funny story... I tried Seafoam the next day. I read online to put a funnel into the booster brake line and let the car take sips. From what I saw online the car produced a small amount of a smoke during this. Then I read at the end of the bottle to dump it in and let it kill the engine and let it sit like that for a half hour or so. When you started the car again it would produce a decent smoke show.

In actuality... during the sipping process my car made so much smoke I literally covered the street I was parked on and across both sides of the street. Our poor neighbors next to us were having a BBQ and all the kids were running around screaming things (they were speaking Spanish so no clue what it was). After the wait I produced so much smoke it looked like a massive war zone and in embarrassment I drove down the block and parked street side. While idling the smoke covered the street area so much I couldn't see anything behind me for about 2 minutes. A few people drove by and stared in horror as if my car was about to explode. Then when I drove around the neighborhood I couldn't see much behind me for quite awhile. I honestly was not expecting that much smoke, that thick, for that long. No clue if it did anything for the engine or not, but wow. That was sorta crazy to experience. I wish I had one of those lighted cameras you can put down the cylinders so I could have seen a before and after.

Which is why they instruct to do it in a well ventilated area. Preferably nowhere public.

Yeah... woulda been nice to still live in MT for that one...
The videos really didn't look that bad. At least the ones I watched it produced just a tiny bit during the sipping, then after turning it back on it was like a little cloud for 30 seconds. This was just massive and never ending. I wasn't expecting that.

Well dang... so the car has started to act up again. It's starting to falter/stutter more and even almost died on me a few times. Triggered a CEL again and after scanning it I got: P0172 Bank 1 and P0175 Bank 2 (System too Rich). I did some searching online. Looks like cleaning out the MAF sensor with compressed air is the best way to start this hunt?Any other suggestions welcome. I'll update the progress.

Cleaned the MAF. Like an idiot I took apart the top half of my CAI to get at it instead of just unscreweing the two little screws. Oh well. I cleaned the pipe up all shiny since it was out. So I bought some CRC Electronic cleaner and hosed everything out really good, I let it sit overnight and dropped it back in. Now I'll just get to wait again until it throws a code I guess. If it throws the misfire in cylinder 3 code again I'll swap out the injectors then look at replacing. If it throws the system too rich code again I guess I'll replace the 02 sensors upstream? On the plus side with this issue I guess it's not such a massive problem that I can't drive the car, but on the downside it's STUPIDLY frustrating to not have immediate results. Sometimes it doesn't act up for throw a code until months later.

On a semi related question: Anyone have any advice for cleaning CAI piping on the exterior? I used some windex and scrubbed it with a paper towel. While it got it shinier it really only took off the dusting. There's a lot of spots of crap on the tube I'd like to remove if possible. It's cosmetic though, so if I can't ohhh welll.

all those misfires will or are destroying ur cat converters. have u had any more problems?

I have a few small hesitations during initial acceleration on random occasions. I need to do further investigation on it, but it's added to a list of things I need to work on. For the last near two months I've had nothing triggering the CEL and no massive bogging down for periods of time like before. I have to get my timing/serp belts replaced, work on my suspension/get an alignment, then I'll look into this more. I'm actually not really sure where to go from here. O2 Sensors? Fuel Injectors? New cat?