98 century 3.1 missing after spark plug change

[bagwellbill]

i have a 98 buick century has around 180000 miles and it ran perfect, then two days ago i changed my spark plugs b/c they were 2+years old i got NGK Vpower and gapped them to .06. i had to roll the engine forward when i got to the back 3 plugs. so anyways after all pugs were changed i took it for a drive it was running fine, then i noticed when i got on the highway when i had to accelerate it missed a few times then on down the road it would go fine until i had to give it a little gas. it jerks a little bit and it sounds like shit. But it idles alright and light acceleration thru town is fine. i also had it tested at autozone and i got a bunch of stuff about vacuum something and 02 sensor but nothing about misfire or coil pack malfunctioning. all the vacuum tubes on the engine are all sealed that i can see. and like i said it ran perfect before hand so i know its nothing internal. i just cant figure what happened

[Tech II]

Did you have a misfire BEFORE changing the plugs?

If you didn't, then obviously there was a problem with the installation....

One thing I tell my friends....you work on a Ford, you put in a Ford plug....you work on a GM, use GM plug....always use OEM's.....

If there was no misfire before, you could have cracked a plug on installation(especially in the back) or had a bad plug.......

What about wires? Did you reuse the one's on the car? You could have damaged one or more of the wires, yanking on them if they were tight on the old plugs...Also, pull the wires, one at a time from each coil terminal and check for corrosion/carbonning.....


I think the purge valve is behind the ICM/coils....there is a vac line and purge line from the canister attached to it...make sure they are attached....

[bagwellbill]

no misifre before. the plugs are fine and not cracked, but i did use old plug wires but wouldnt the computer have saved a misfire code or something?

[Tech II]

There is no code for a coil misfiring.....as for a misfire setting a code, or P0300, it has to happen a certain number of times, in a precise time frame....if there aren't enough, the code won't set.....if there are, the CE light still won't come on until the second key cycle in which it fails.....however, if the misfires are so numerous they can cause catalytic converter damage, the CE light will begin to flash, to warn you to decrease the load on the engine......

While the plugs may be ok, if the boots were "baked on" the old plugs, and you had to twist and yank the boots off, you could have damaged the old wires......

Those rear boots can be a bugger to get off sometimes.......and sometimes the damage to the wires may not show up immediately.....could even have a coil problem......but I am leaning towards the wires.....

[bagwellbill]

i was kind of thinking it was the wires also because they were baked on pretty much but i was making sure not to pull the actual wire but the rubber piece that ur supposed to pull.. and also i was on the highway today and it tried to stall out going up an exit ramp so i gave it some more gas to get off the incline quicker after the acceleration it was misfiring constantly until i was on level highway again but as soon as i got to the top i smelled burnt rubber for a min or two