NBM-LS1

iTrader: (7)

Alright here is my problem. Installed headers a few weeks back. Never really put my foot into it until a few days ago. She misfires, occasionally. She drives normal at normal speeds but when its time to race she misfires up top. The other day I was on the on ramp in 3rd and was good untill i got up in the rpms and then she started to miss. I was like ok lets try again. Put it in 3rd on the highway going about 60mph and eased into it slowly. No missfires and shifted into 4th.

Went home checked all the plugs and wires to make sure and none of them ar cracked and all clipped on securly.

Not day. slow roll first gear to 2nd. No problems at all through the rpm range. Tryed it again to make sure and it started to miss. Went on the highway and it did it in 3rd again.

Not sure what to do. The other day had the car apart and was painting the valve covers and coil brackets. Had all the coils off the brackets and such. I checked and everything i unplugged is pluged back in. I dont think I missed anything.

So I am running off road header, ory with all o2s pluged in. Is that ok?

and my plugs are NGK-T55s gapped at .55 with MSD wires.

Why am I getting an occasional miss? It will normally do it when I mash the pedal but when I get into it slowly it wont do it.

I am changing out the fuel filter tomorrow and then I will check again.

Should I buy a new set of plugs? Its untuned as well and running on the rich side.

tennz28

IMO get new plugs and clean your MAF

NBM-LS1

iTrader: (7)

Anybody else?

NBM-LS1

iTrader: (7)

ttt

...

wicked z28

iTrader: (9)

Maybe Your O2 Are Bad They Usually Go Out After Headers And Ofry And Thats The Front O2 The Rear Ones Dont Do Anything But Tell The Pcm The Cats Are There Or Not.my O2 Went Out Not Too Long After My Header And Ofry Install It Slightly Would Hesitate When I Would Leave A From A Stop And Then It Just Started To Get Worse It Would Just Backfire Out Of Nowhere.a Loud Pop And Would Drive Fine Untill Later Weeks Of Driving Then It Just Started Misfiring Like Crazy.bought New O2 And Problem Solved.i Heard You Can Put The Rear Ones In The Front Also Maybe Swap Out And See What Happens Or Just Get New Ones Theyll Eventually Go Out If You Dont Get It Tuned Its Going To Be Running Rich And That Meses Up The O2.

NBM-LS1

iTrader: (7)

anyone else have an opinion?

pumkin rs

i got that same thing after i installed my headers. i just upgarded to high temp wires. It cleared it right up.

MagnaTransAm0098

iTrader: (10)

same exact problem here also, but I also get a miss at idle when its cold...has to have somthing to do with headers ive read a few different posts with the same problem all with headers..Ive tried 6 different O2's and the high temp wires wouldnt make sense considering I have the miss after about 30 seconds at idle. wish there was someone with the same problem who has cured it!

stangbangin69

iTrader: (26)

one of my msd wires were broken where it attaches to the plug. it still attached fine but at higher rpms it would break down and misfire... i just changed the whole set to a set of gm performance wires and no problems anymore .. runs like a raped ape

jmilz28

iTrader: (13)

Ignition misfires tend to get worse as the engine heats up. i.e. as temp increases, so does resistance. Fuel related misfires TEND to be the opposite.

You may have fouled the plugs running untuned, that's my guess. If you have cats, running rich will clog them and make them die prematurely.

~BuMps AloT~

iTrader: (5)

Get a tune. And it should clear things up. Like previously stated your running rich, fouling plugs and o2's.

93LEETZ

+1.......

NBM-LS1

iTrader: (7)

Well I cured the problem. It was either the plugs or fuel filter. I took the plugs out last night and gapped them from .055 to .040 and it runs smoother. I also changed out the fuel filter and runs like a champ. Maybe you guys should try regapping your plugs?

Now if only I can get my rasp fixed. LOL!

Sunset'01Z

iTrader: (10)

i'm not really sure those plugs are supposed to be gapped that small.. you still need to get the car tuned. goodluck

NBM-LS1

iTrader: (7)

Well it sure is running better since then.

What would be the disadvantage to having them gapped too small.