Have a2000 v 6, and for quite a while ive had a misfire issue..ill try to explain but im sure ill end upeaving some things out, please just bear with me..


First off it was an intermittent issue, which was fixed by cleaning up and greasing the coil pack terminals. Fine and dandy for a couple months when it got really bad, and i pulled one wire at a time, and turned it over not fully starting it, from my 2/5 coil pack and neither were sparking, where as you probably know, they will usually arc out. So i replaced all 3 coil packs which was great, most power its had and great gas mileage, but by the end of that month i began to have serious issues, due in part to a failed egr valve which has been replaced. Misfire continued. I did the same test as before on all 6 wires at the plug and all were firing. Now one thing that confuses me, and i was doubtful of for a while ia ths fact that the higher the humidity, the better the car runs (less appearant/no misfire). I finally was convinced when today after it had rained there was no issue at all on my way to work. (its only a couple miles, but there are a few stop signs, which taking off and accelerating are where i see my main issues.)

Plugs and wires were replaced and the issue stayed
No cel light since egr valve was replaced (it was only an egr code anyways)

Im sort of stumped and getting tired of the headache soo..thanks for any help.

 

Check wire routing for arcing... How old are the plug & wires? Did you have the injectors NOID tested?

Also, do you still have the heat shields on the plugs at the block? I was told by a GM Service Tech that they are a source of problems too -- I removed mine when I added MSD wires and Denso plugs...

 

Misfires can also be caused by fuel issues. If you get no fuel you get no bang and that acts like a misfire, actually it is even if the plug fires. Injectors that have bad coils in them will trip codes but clogged injectors usually do not. I would try cleaning your fuel system, check your fuel pressure regulator (pull off the vacuum line and see if fuel is coming out of it. If so replace, if not apply a vacuum pump and gauge and see if it holds vacuum, is should). If you suspect clogged injectors they may need to be properly cleaned by an injector specialist. Check the phone book for your local shop.

Massey

 

i agree with massey deff sounds like an injector problem but you should start it at night open the hood and see if you see any sparks maybe a wire melted or new wires arnt always perfect but ill deff say im thinking fuel

 

I sez clogged fuel filter ^_^

 

I agree with Massey, check the fuel system, if it checks out, try your ICM. I had an ICM (ignition control module) go out on my 3.8 firebird and when I scanned the code it came up as Random Multiple Misfire. I happened to have an ICM laying around from another engine, so I swapped it out (it only takes about 20mins) and that fixed the problem. New I think they are in the 125-150 range. You can pull yours and take it up to autozone and have them test it to see if it's good. Just incase you didnt know, the ICM is what your coils plug into. There's a screw on the back side of it that holds the plug in. It took me a while to figure that out when I was pulling it. But other than that, its easy to pull. And it wont cost you anything to have it tested.

 

Ahh Ahh great to see so many replies, thanks to all who commented.

Liberty, plugs and wires are around 8-9k miles so i suppose they could stand to be changed, but have been changed just after i first noticed the issue, and was not bad at all. Havent had them tested, all the work has been done by me..which is likely half my problem lol..and iit seems like i reat that about the heat sheilds every time im on here and never think to take them off, but i will try that.

Massey, i will check that this weekend, the manual is at my parents house, and if i dont have pictures, im usually not gonna be able to tell anything apart from anything when it comes to vacuum lines, and i dont THINK its the injectors, but its very likely that im wrong haha

Basic, i did that and didnt see anything, but i do think i can hear the arc sometimes, but my power steering pump is so damn loud i cant think

Evikal, i have actually been meaning to check this haha..also changed it when i first noticed the issue, and it was so clogged a hooker couldnt have sucked air through it, so im sure it probably needs it again haha.

Torque, i do suppose it could be the icm, being that i had a coil pack go bad, maybe its allowing too much (oltage or something, and thanks for the heads up on that screw, i about lose my mind every time i mess with those coil packs..no room for my fat hands lol..

But again, im confused about the humidity causing things to run more smoothly..would any of these things allow that?

 

Ahh Ahh great to see so many replies, thanks to all who commented.

Liberty, plugs and wires are around 8-9k miles so i suppose they could stand to be changed, but have been changed just after i first noticed the issue, and was not bad at all. Havent had them tested, all the work has been done by me..which is likely half my problem lol..and iit seems like i reat that about the heat sheilds every time im on here and never think to take them off, but i will try that.

Massey, i will check that this weekend, the manual is at my parents house, and if i dont have pictures, im usually not gonna be able to tell anything apart from anything when it comes to vacuum lines, and i dont THINK its the injectors, but its very likely that im wrong haha

Basic, i did that and didnt see anything, but i do think i can hear the arc sometimes, but my power steering pump is so damn loud i cant think

Evikal, i have actually been meaning to check this haha..also changed it when i first noticed the issue, and it was so clogged a hooker couldnt have sucked air through it, so im sure it probably needs it again haha.

Torque, i do suppose it could be the icm, being that i had a coil pack go bad, maybe its allowing too much (oltage or something, and thanks for the heads up on that screw, i about lose my mind every time i mess with those coil packs..no room for my fat hands lol..

But again, im confused about the humidity causing things to run more smoothly..would any of these things allow that?

 

Humidity can cause corroded connections to make better contact and work while wet. This is not uncommon and can be fixed with a wire brush and some dialectric grease. do not use bearing grease or any other type of grease other than dialectric it is not conductive, made for electrical parts. This stuff is usually milky clear or white and will keep out moisture, and dirt and also help displace heat faster. I would start checking for corrosion on your ICM and coil packs.

Massey