Unknown source of misfire/backfire
Thread Starter
Joined: May 2006
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Unknown source of misfire/backfire
Possible fix solution in post #12 and #18
So let's take this back a few weeks. My car was misfiring due to a stripped spark plug. I timeserted my head and made a timesert DIY a few weeks back. I had bought all four brand new coil packs and four brand new sparkplugs. Installed it, drove fine for a few days. One day, I noticed a little misfire but no CEL. It went away and I didn't experience anything else.
A couple days ago, misfiring came back and it came back really bad. While cruising, the car would misfire and that in turn would cause a couple backfires due to the unburnt gas. Still no CEL. I shut off the car, turned it back on, completely normal. I drove to a restaurant to meet my friends with no hiccups. Started the car cold, bad misfires. Sounded like a Subaru with unequal length headers. No CEL. Revved it up, goes away, idles, comes back. So I
decided to just drive home because no CEL and the issue goes away with some throttle.
Yesterday, 1/2 mile away from home, it starts misfiring really bad on the freeway. Sounded like a Subaru again. This time, CEL starts flashing. I shut off the car and roll it off the freeway. I caught the green light on the offramp and rolled to the side of the street. Put the ignition on the on position, no CEL. Turned the car back on, COMPLETELY NORMAL. This is driving me nuts. Pulled all plugs and packs. #2 coil pack has some oil on it. This shouldn't be the cause as the sparkplug is completely dry and the inside of the coil pack is also dry of oil, just the outer shell of the pack.
Any ideas? Faulty pack? Something causing the pack to go bad? I have the NGK iridiums and I am not supposed to gap those and they all seem to be within spec. This wouldn't be so difficult if there was a CEL telling me where to start. I don't even know which cylinder to start at. Looking forward to your guy's ideas .
So let's take this back a few weeks. My car was misfiring due to a stripped spark plug. I timeserted my head and made a timesert DIY a few weeks back. I had bought all four brand new coil packs and four brand new sparkplugs. Installed it, drove fine for a few days. One day, I noticed a little misfire but no CEL. It went away and I didn't experience anything else.
A couple days ago, misfiring came back and it came back really bad. While cruising, the car would misfire and that in turn would cause a couple backfires due to the unburnt gas. Still no CEL. I shut off the car, turned it back on, completely normal. I drove to a restaurant to meet my friends with no hiccups. Started the car cold, bad misfires. Sounded like a Subaru with unequal length headers. No CEL. Revved it up, goes away, idles, comes back. So I
decided to just drive home because no CEL and the issue goes away with some throttle.
Yesterday, 1/2 mile away from home, it starts misfiring really bad on the freeway. Sounded like a Subaru again. This time, CEL starts flashing. I shut off the car and roll it off the freeway. I caught the green light on the offramp and rolled to the side of the street. Put the ignition on the on position, no CEL. Turned the car back on, COMPLETELY NORMAL. This is driving me nuts. Pulled all plugs and packs. #2 coil pack has some oil on it. This shouldn't be the cause as the sparkplug is completely dry and the inside of the coil pack is also dry of oil, just the outer shell of the pack.
Any ideas? Faulty pack? Something causing the pack to go bad? I have the NGK iridiums and I am not supposed to gap those and they all seem to be within spec. This wouldn't be so difficult if there was a CEL telling me where to start. I don't even know which cylinder to start at. Looking forward to your guy's ideas .
Joined: May 2004
Posts: 1,531
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From: Tucson
Have you read all the threads on misfires in the stickied DIY area? There is a lot of good info there. No sense in repeating it here. 
https://www.s2ki.com/s2000/topic/548...d-maintenance/
https://www.s2ki.com/s2000/topic/548...d-maintenance/
Joined: Sep 2002
Posts: 1,938
Likes: 4
From: Sydney
When its running on 3 cylinders, unplug the coilpack socket or injector while the engine is running on the one you timeserted and see if it gets worse. The misfiring one will make no difference to the idle when you unplug it.
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Joined: Jul 2002
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From: Long Island, New York
Your problem seems to be electrical to come and go like that.
First off, fix the obvious. No oil should be present in the tubes, and if it is your tube seals in the VC are bad. Thorough inspection will reveal a bad tube seal, and you can just change the ones that are damaged (it is common to damage them upon install, it is very UNCOMMON for them to ever just go bad)
Remove the plastic injector cover and leave it off for now. This will give you access to the injector clips for the future test.
Follow chris_barry's advice. Next time you can get it to misfire, disconnect each injector electrical connector one at a time. The cylinder which shows no change while disconnected is your misfiring cylinder.
I would also get a cheap code reader, to monitor which code is setting first.
First off, fix the obvious. No oil should be present in the tubes, and if it is your tube seals in the VC are bad. Thorough inspection will reveal a bad tube seal, and you can just change the ones that are damaged (it is common to damage them upon install, it is very UNCOMMON for them to ever just go bad)
Remove the plastic injector cover and leave it off for now. This will give you access to the injector clips for the future test.
Follow chris_barry's advice. Next time you can get it to misfire, disconnect each injector electrical connector one at a time. The cylinder which shows no change while disconnected is your misfiring cylinder.
I would also get a cheap code reader, to monitor which code is setting first.
Thread Starter
Joined: May 2006
Posts: 567
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All of this information is great, except I never know when the misfire will occur, nor does it stay misfiring. It usually goes away before I can pull over. It comes and goes that quickly. Hopefully it'll misfire again as I turn the car on so I can just pop the hood, but that only happened once. I just want to know why I don't have a CEL. As bad as it misfires, it should have thrown a code. The tube seals in the valve cover went bad probably due to the fire. Spark plug came off, combustion burnt up the coilpack and in turn, im sure it burned off the seals. This is becoming a headache. I still have to fix my blown second gear. HAHA this is so bad. Hondas are unreliable. 
Even if I were to find which cylinder is the misfiring cylinder, how do I find out whats causing the misfires?
*Edit: Read the misfire thread. If none of those suggestions help, I will come back. Thanks Billman, Random, chris, and starchland.
Even if I were to find which cylinder is the misfiring cylinder, how do I find out whats causing the misfires?
*Edit: Read the misfire thread. If none of those suggestions help, I will come back. Thanks Billman, Random, chris, and starchland.
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Thread Starter
Joined: May 2006
Posts: 567
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Thread Starter
Joined: May 2006
Posts: 567
Likes: 0
Found it. Sat there with the hood popped and injector cover off for God knows how long. Started misfiring and I jumped up and started popping the plugs off. #2. I'm still stuck. Brand new coilpack? Brand new spark plugs? Injector? MAP has been whacked. Can't be the alternator. Not the TPS. POSSIBLY the oil leak in the coilpack tube.