inspiredbykev

iTrader: (35)

Started up my car yesterday and noticed the ses light came on. Went to autozone and the code was P0300 (multiple cylinder misfire) and I had the guy clear it and light hasn't come back on.

I have hotshot headers installed with the o2 simulator.
L-SPEC ecu and safc-II untuned. I know our cars run rich factory and even more with headers installed but with the ecu my revs are up to 7100 now. I took it up there lots of times so could this have fouled my spark plugs.

I never replaced any coil packs or the spark plugs or any o2s.

Should I just keep driving around until the light comes back on or do something now?
Even though the ses light was cleared could I be damaging the motor by driving around?

I planned on getting my car tuned later on this month but I don't want anything affecting my motor when I'm on the dyno. I just want everything to be running right when I do the dyno so I get the best results.

MAXRB8

iTrader: (19)

Do you notice any missing? I don't have headers etc, but I got that code, I could bring it on by flooring the car under load, turns out I had a bad coil pack with only 50,000miles on the engine. Not sure which one it was as I replaced them on all thanks to a sweet deal from Steven88, I should really find out which one it was so I will have 5 good ones for backup.

inspiredbykev

iTrader: (35)

yea I have 52k right now.

Should I go and get my car tuned then replace all of my spark plugs and coil packs?

MAXRB8

iTrader: (19)

If you are going to change the coils you might as well change the plugs as the intake manifold needs to be removed to change the back three, but coils are big $$$ so see if you can source out a used proven working set first, just incase the coils are not your problem.

inspiredbykev

iTrader: (35)

just ordered new coils $400

Already had new ngk plats in my closet because I was planning on changing them. Good thing this code popped up now so I can one shot everything. I think that when I replace the coils and plug it will fix the problem because I know my car is running rich and it probably fouled a spark plug.

Should I get my car tuned first then replace my coils and spark plugs so they dont get fouled?

steven88

iTrader: (28)

kev, do you actually feel the misfire under load? if you don't know what it is, its basically a big lag....for example...if you normally shift at 3k....and the misfiring happens around 2 to 2.5k...once you hit around 2-2.5k, it will lag & feel weird like its "missing" then all of a sudden pick up again after 2.5k....

you know, i read a few posts of members have 0300 codes just pop up randomly....especially if your modded...as for me, i use to get this code here and there but never experienced any sort of misfiring under load....

whats important here, is the actualy misfire...if you don't physically feel it under load, don't worry too much....the code is annoying tho...

inspiredbykev

iTrader: (35)

i don't feel anything.

If my car is neutral and I rev it up high I get some crackle. If I had a test pipe I bet flames would shoot out. Right now the car seems fine so I am going to get it tuned sometime soon and then replace the coils and spark plugs so I know my cars running efficient. I just want my car to be running smooth. Don't want it to eventually burn the valves or pistons from being too rich.

I am also running 93 octane do you think that adds to the richness. When I got the ecu back from technosquare it said 92 or higher only.

steven88

iTrader: (28)

if you don't feel anything...don't worry...the misfire is probably just a ghost code....just moniter your SES light and see if it comes back...if it comes back every few months, dont worry about it...if it comes back every week...then something is wrong

inspiredbykev

iTrader: (35)

thanks steve for the feedback

when I get my car dynoed I'll post the #'s

steven88

iTrader: (28)

nice...when are you dynoing? and what is your mod list again?

inspiredbykev

iTrader: (35)

either this tues or thurs
hotshot headers, cattman fastcat, cattman catback, unorthodox udp sc, berk intake, l-spec and many more

steven88

iTrader: (28)

didnt u have safcii as well?

i'm betting 240whp+ if everything is in working order....maybe even 250 if u get lucky

inspiredbykev

iTrader: (35)

yea got that in the sunglasses holder

im gonna be sellin my old coil packs soon how much u think I should try and get them 4?

also one of my boys told me to replace the o2 sensors after I get my car tuned. I told him that I gonna wait until them codes pop up. You think I should get new ones. All I would need are the two primaries because I have the o2 simulator tricking the last two o2s

steven88

iTrader: (28)

I say dont bother with the coilpacks until you actually feel the car misfiring....i don't as many vq35 coilpacks failing versus vq30 ones....but since you said you bought them already....then go for it...i guess $150 would be a good starting price

you don't have to replace the o2 sensor...unless its actually bad...even if it was bad, it won't affect the tune that your s-afcii is doing....o2 sensors only modify closed loop tuning....afcii only modifies open loop tuning and the o2 sensors DO NOT change the afcii's tune....i ran my car on the dyno with BOTH o2 sensors disconnected and still pulled the same #s with them connected....i tuned on the dyno for quite awhile and nothing changed...