Irocwagon

99 z28 6spd, slp air intake

I changed the plugs and wires and fuel filter. The car was running great before any work. Now at idle it misses. Sounds like light popping. Driving it still has power under acceleration, when cruising it'll feel like light miss firing, no cel. I used ac delco platinums with the .40 gap , and ac delco wires. It had ngk with a lil over .60 gap in it but were severely worn but it ran great. I have no idea why it's running bad. I've double checked everything I took off. I've checked The exhaust manifolds for each cylinder with a heat gun and they're all within 20 degrees of each other. Could the .40 gap be causing the problem even though that's what the 98 called for?

gbrooks91

well my first question is what mods have you done first

Irocwagon

Just the slp intake and it has a flowmaster on it.and ls7clutch

gbrooks91

Ok well that doesn't make sense why it's doing that the first thing I would do is check and see what type of codes it's throwing mine did that when I first bought it about 4 months ago and it turned out to be bad gas but I would also check the coil pack as well once you figure out which cylinder is miss firing

Irocwagon

That's the problem. It's not throwing any codes. I took it on three 30 mile drives with mixed driving. I tried unplugging coils, that threw codes and ran rough as expected. With everything back toghether it's the same. I see people saying they've ran from .40 to .60 without any issues. Any problems with the platinum .40.

gbrooks91

Thats really weird it should throw a code with a miss fire does it shake under acceleration

Irocwagon

Every now and then but normally it pulls hard as normal, it'll light the tires up effortlessly (I have 275/40)

King Nothing

iTrader: (9)

Did you clean your MAF and IAT also?

Irocwagon

No I didn't clean anything.

gbrooks91

i was about to ask that cause if it's not throwing a code the it's either trash in the gas which is possible or something is clogged

Irocwagon

It actually smells like it's running richer

Irocwagon

Exhaust smel was clean before, now it kinda smells like gas

gbrooks91

yeah mine does that too butt I'm also running no cats just a flow master

gbrooks91

check and make sure all your plug wires are on all the way and then if that doesn't work I would say regap the plugs and try again it's always something simple we over look

Irocwagon

I'm debating on the plug. I see a lot of people run that ngk plug

inrechecked all wires. I checked all gaps, they were dead on .40. What's gaps do y'all run?

gbrooks91

yeah I've heard the ngks are the beat for ls cars but I'm running Bosch double platinum plugs with no problems and royal purple 5w20 or 30 I can't remember now but it runs great

Irocwagon

Spending New Year's Eve working on this car, no parties for me

gbrooks91

trying to think here it's possible of the plugs could be filed out already I've seen that before where a spark plug is bad out the box

Irocwagon

Well I guess I'll buy some Ngks , I didn't think I could go wrong with the ac delcos

gbrooks91

lol well I'm not really sure on what to tell other than it may your gap on the plugs may need to be slightly bigger