misfiring at WOT, changed plugs
 

Engine starts to misfire a little under heavy acceleration. Its not very loud, sounds like popcorn popping. No backfires.

I didnt have much time tonight so i was only able to change all the plugs on the driverside, and took it for a drive and its still occurring. The plugs i took out werent worn that bad really, but the gap was huge! i put in new bosch platinum plus plugs with .050 gap.

tomorrow evening im gonna switch out pass side and hope that helps. i checked the intake side of things and the filter was clean, and the maf (which i descreened long ago) was clean, and the wires looked fine.

Anything else i should check? how do i know/check to see if a coil is bad? all my wires are tight, already checked that.

car idles really smooth and runs well until you floor it and then it starts to pop as the rpms climb

thanks fellas

Here are the four plugs i took out from the drivers side. plugs 1,3,5,and 7 last plug is a new one gapped at .050 to show difference
http://i55.photobucket.com/albums/g1...g/DSC01945.jpg

i ended up gapping mine abit smaller then that, quite abit actually. Gapped mine at .035, and it runs like a top now. had the others at .060, and was having bad misfiring/backfiring. Yours look huge tho, im sure the new plugs will help out a ton man!

hope so

Bosch platinums suck, before you lose the skin off the back of your thumbs, I would take them back and get NKG TR55ix. I would get new ignition wires also. I had a bad connection to a coil pack and mine had a studder around 1500 rpm. You would probably have to use a volt meter to check the coil packs. I would do the plugs and wires and go from there.

You know one other thing you mentioned was descreaning the MAF. Man, Im a firm believer in not doing that. For the gains, if any, that you get from doing that, and the chances of throwing garbage in that engine is so not worth it. If I were you I would consider putting that screan back on. And I love the NKG's by the way, I think they are tops for plugs. Good luck. Keep us posted on if you get the problem fixed.

it seems people either love or hate descreening the maf, and people love or hate bosch plugs.

personally i think that if many aftermarket mafs come descreened(which they do) then taking it out of the stock cant be that bad.

second, i think a platinum plug is a platinum plug is a platinum plug. i could see if you recommended iridium vs copper, or platinum vs iridium. the ngks and bosch are made out of the same materials, they are close in price, and are the same size/fit. any differences between the two are minimal im sure, and are probably mostly due to marketing if anything.

but anyway im not here to debate brands, so ill keep you posted on this...

thanks for the input tho

o yea, both plugs have the "V" in the tip also

I would certainly change the wires too. You can't really tell by looking at them if they have small breaks. Wires going bad will tend to show up under a load, and since your misfires are at WOT you should do the wires too.

As for Bosch platinum plugs, I used them when I had air cooled VW's hot rodded and they were good, put them in the first Firebird I bought and the lasted 20k only. Tried again, same result. Staying with what I knew was a bad decision. Lot of experience on this site and you will find that people either use the NKG's or the Irridiums. I use the Irridiums. Just advice.

whenever u change the plugs, if that doesnt help and your car still misfires, put some Lucas injector cleaner in your fuel, that stuff helped my car alot,thats all I've used in all of my vihecles,I personally love it!. good luck

Are you throwing any codes? My car started doing that and it got progressively worse. I spent alot of money replacing O2s, plugs, etc and it turned out to be a bad crank position sensor. If you have disconnected it for any reason, you may need to have a tuner do a relearn on that sensor.

First off let me say thanks guys. this is why i love this site and our community. we are always willing to help each other. :thumb:

yes, new wires are gonna be going on next when i put in the rest of the new plugs. time is a killer for me during the week, but this weekend i should be able to find time. im hoping this fixes my problem but even if it does not, im not too upset because the car is a 98 with 70,xxx miles on it and they had never been changed before. its probably time for new ones anyway.

I did a search on here earlier and saw some people had this problem caused by either dirty injectors or a clogged fuel filter, i forgot to mention i ran a bottle of injector cleaner through it on monday and tuesday of this week and it didnt help. the fuel filter is new as of 10,000 miles ago, so i doubt its clogged already.

so to recap: finish plugs and wires next, go from there to more serious issues...

forgot to mention, not throwing any codes, and im still on the stock manifolds, cats, and 02s, gmmg is the only exhaust mod. ive read some people get this problem after a header install, which then is fixed by a tune, but i doubt this is related.

I see it says you have a stall, what size and how long has it been in there? If it shows you what cylinder it is misfiring from you could change that coil with another and that will tell you if it is bad.

Could bad plugs cause a wierd vibration at only a certain amount of throttle? My car feel like its a diesel when you hit about 10-15% throttle and then it goes away.

3200 2.0str why does that matter?

Well after changing all my plugs and wires i think there should be a new posting rule. no one can post until they have changed their own plugs and wires!!!! damn that was a bitch. number 8 is hell. had to get it from the bottom. took about 3 hours to do them all cause i had to run to autozone to get a 1 3/4" extension. to do it again would only take about 45mins to an hour i bet. all in all im glad i did it and learned from it.


but back to the problem. after changing the plugs and wires the problem is SOLVED. not misfiring at all now. runs smooth starts faster and sounds better. none of the plugs looked really bad as pictured above, but they were all gapped at right around .070. anyone know why factory ac delco plugs would be gapped so high? did they just wear out and open up that big? my guess is that a wire was bad as was mentioned above. but at any rate, im happy thanks boys