Can't figure out misfire
Thread Starter
TECH Enthusiast
Joined: Aug 2003
Posts: 546
Likes: 3
From: Northeast TN
Can't figure out misfire Hey, I was out driving around with friends on Sat, and my car started running really rough and surging and such. We stopped by a local parts store and had the codes ran in it. Said I was misfiring on #6. The wierd thing was that the longer I drove the car, the less it would do this. On my way home, the car ran perfect. Yesterday on my way to work, it drove perfect.
So last night, I swapped the plug wires in it, and now its doing it again. We were sure it was the wire, since it would come and go. Wouldn't think a coil or plug would do that, figured it would be more consistant. Am I wrong? Gotta fix it today... Thanks.
Kelly
So last night, I swapped the plug wires in it, and now its doing it again. We were sure it was the wire, since it would come and go. Wouldn't think a coil or plug would do that, figured it would be more consistant. Am I wrong? Gotta fix it today... Thanks.
Kelly
Thread Starter
TECH Enthusiast
Joined: Aug 2003
Posts: 546
Likes: 3
From: Northeast TN
Think I may have found something useful. I hope this isn't it but we'll see...
http://obdii.com/articles/Engine_Misfire_UC.html
http://obdii.com/articles/Engine_Misfire_UC.html
Well, if it is an intake manifold leak, it is pretty easy to fix.
I'd replace all 8 individual gaskets (which is not that expensive) and within 2 hours, you'd be set.
Good luck.
I'd replace all 8 individual gaskets (which is not that expensive) and within 2 hours, you'd be set.
Good luck.
Thread Starter
TECH Enthusiast
Joined: Aug 2003
Posts: 546
Likes: 3
From: Northeast TN
Well get this:
Last night I decided to look around a little more on the motor and see if I could track down any kind of leaks. My car had been making a very audible hissing sound for a while now, and so I knew it was sucking air somewhere. I was looking with the engine running, and happened to put my hand down at the base of the intake to throttle body area on the pass side, and I felt air. I touched a hose there and it sucked my finger to it, and the engine idle dropped a little. Turns out the little 2" piece of hose that connects from the PCV to the intake had a hole in the bottom side of it. I replaced it with a small piece of heater hose and it was done.
Since, my car has ran perfect. I started it this morning to go to work, and let it idle for a minute before taking off. The SES light was on, but there was no stalling or misfiring that I could hear. This afternoon when I left work, I started the car, SES light still on but no misfire. I let it idle for a few minutes while I was making a call. Then when I got ready to take off, I noticed the SES light had gone off, and all the way home there was not one hint of anyting being wrong. Now, how could this vacuum leak cause my #6 to misfire, or was it even the cause of it? Is there maybe something else wrong as well?
Last night I decided to look around a little more on the motor and see if I could track down any kind of leaks. My car had been making a very audible hissing sound for a while now, and so I knew it was sucking air somewhere. I was looking with the engine running, and happened to put my hand down at the base of the intake to throttle body area on the pass side, and I felt air. I touched a hose there and it sucked my finger to it, and the engine idle dropped a little. Turns out the little 2" piece of hose that connects from the PCV to the intake had a hole in the bottom side of it. I replaced it with a small piece of heater hose and it was done.
Since, my car has ran perfect. I started it this morning to go to work, and let it idle for a minute before taking off. The SES light was on, but there was no stalling or misfiring that I could hear. This afternoon when I left work, I started the car, SES light still on but no misfire. I let it idle for a few minutes while I was making a call. Then when I got ready to take off, I noticed the SES light had gone off, and all the way home there was not one hint of anyting being wrong. Now, how could this vacuum leak cause my #6 to misfire, or was it even the cause of it? Is there maybe something else wrong as well?
Trending Topics
I would bet that it had something to do with it. Vacuum leaks will kill you. Un-meter'd air, i.e. air that is being inahled past the MAF will reek havic on your pcm and engine management.
I'd give the car a week and see if you have any more SES lights.
I'd give the car a week and see if you have any more SES lights.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Thread Starter
TECH Enthusiast
Joined: Aug 2003
Posts: 546
Likes: 3
From: Northeast TN
Well, I drove it some more tonight, and it never once stumbled or misfired (at least that I could tell). I know I do have an O2 sensor problem, cause it threw a code about it. But, I am wondering if the leak could have caused my car to lean out, also causing the o2 code to be thrown. Anyone? Car did seem like it was idling a little rough, but as soon as I start moving, it is perfect.
TECH Resident
Joined: Jul 2004
Posts: 813
Likes: 0
From: It's hard work to look this good
when i had a misfire on #6 I replaced everything under the sun, plugs, wires, injectors,
coilpack (coilpack/ swapped with a different cylinder to see if the code would fallow) nothing worked. It ened up being bank2 oxygen sensor had freyed melted wires so it was grounding out every now and then. You might as well replace that also. You also might want to clear your SES codes now that you think you got it fixed. this way if it pops up again you will know.
coilpack (coilpack/ swapped with a different cylinder to see if the code would fallow) nothing worked. It ened up being bank2 oxygen sensor had freyed melted wires so it was grounding out every now and then. You might as well replace that also. You also might want to clear your SES codes now that you think you got it fixed. this way if it pops up again you will know.
Teching In
Joined: Sep 2003
Posts: 20
Likes: 0
From: Antioch,Ca
I had the same problem, except it was the #7cyl. I changed everything under the sun. I had a 02 sensor crap out also. The fix????? The o-ring on the egr tube which goes into the throttle body was sucking in. The brass insert into the intake was pulling out. I got it back in and haven't had a problem again. You definately have a vacuum leak prob. I had a bunch of different codes and the problem was never consistant. Hope this helps.
Thread Starter
TECH Enthusiast
Joined: Aug 2003
Posts: 546
Likes: 3
From: Northeast TN
actually that helps a lot. The car is still doing this crap. The thing is, it only does it at startup. After it idles for about a minute or two, it will start to misfire. If I take off then, it will continue to do so. If I wait about 30-45 sec, it will clear up completely and run perfect until the next startup. It's soo wierd! Would it be smart to just do an EGR delete, or should I keep it and fix the o-ring (cause I have noticed every time I have pulled it out of the intake, the ring is lopsided, or pulled down on usually the drivers side.)?
Teching In
Joined: Sep 2003
Posts: 20
Likes: 0
From: Antioch,Ca
The EGR seal should not pull down at all in the intake. Make sure the brass insert is flush with the intake and not pulling out. Also, you should probably change the seal if it has stretched. The whole setup with the 1 bolt holding the tube in is BS in the first place. Good luck...
