Eiyse98ls1

well as the title says i got a p0300 engine misfire code. i pulled plugs 1,3,5,7 and i think they look alright. i took pics that can be seen in my sig. please adivce to what i should look at next after i check the remaining plugs.

thanks

CHRISPY

miss a shift lately? rev limit a lot higher than stock? If so you might have bent a pushrod

Eiyse98ls1

actually my freind was driving the other day and he did rev it pass redline. and even told him to shift cuzz he was past 6000-6100rpm. did you see the plugs? how do they look?is there a distinct sound when you have bent pushrod? i have had the car on since then but it sounds normal. it idles real rough and the car starts to shake occasionally while im trying to scan.
i hope its not a bent pushrod

thanks
TTT

SmokingWS6

iTrader: (1)

Nothing wrong with 6000-6100. I believe he means a miss shift such as going from 3rd to 2nd instead of 4th at wot, which would put your rpm's well over 7000.

Check your plugs and wires, clear the code and see if it comes back.

Eiyse98ls1

alright the rpms didnt go past 7k. it did past 6100 though. i got the driver side check next ill check pass. side. driver side looked fine.

SmokingWS6

iTrader: (1)

Best of luck, maybe it was a fluke, bad gas ect.

6100 is ok on an internally stock motor, my 2-3 shift occurs at 6150 - 6200rpm.

gillbot

iTrader: (27)

P0300 is a random misfire. Do you have a cam or anything or is the car basically stock?

Eiyse98ls1

car is basically stock

Eiyse98ls1

alright i checked plugs 1,2,3,5,7 and all look good. i hooked up the scanner (atap)and showed that all cylinders are misfiring. everytime i rev up the engine the misfire counts increase. what should i look at next.?

thanks

SmokingWS6

iTrader: (1)

More importantly how does it run? Any lack in performance or does it feel fine? Try using a different gas station next time you fill up.

If everything mechanically checks out, motor runs good ect i'd look into disabling your missfire counts or raising the limits. Methods on how to do it can be found in the pcm tuning sticky.

Eiyse98ls1

havent ran it since the code come on. when the code came on it was running real rough and no throttle response. so i parked it. after a couple of days i scanned with atap. i logged 3 seperate times and out of the 3 times 1 didnt havent any problems then the other two it idled rough for a few seconds a couple of times.


what are all the coils connected to0?ecu?ckps?

Y2K SS

iTrader: (1)

I had that code before my updated mods every now and then. The past weekend I added heads, ls6 intake, ported TB, PCV conversion, MSD wires, plugs, and new pushrods as well. Ran it this week and got the code again. My car runs fine and when I dynoed it with just the cam and LT's I got 350 rwhp. I've been told its a bogus code sometimes and guys just delete it.

Eiyse98ls1

another log and the idle pretty bad the whole time. i recognized that the ftlt bank 1 was at 25% and -9-10% on bank 2 this is at idle

gillbot

iTrader: (27)

bad gas perhaps? You run premium?

SmokingWS6

iTrader: (1)

could be a sign of a bad o2, or perhaps a stuck or static injector. Something is happening on the drivers side of the motor that is causing big problems. Time to pull all the plugs and see how they look.

Eiyse98ls1

premium gas it is. and plugs i have pulled and look good. hopefully a freind that works at dealer can piont me in the right direction. he cleard the code and it came back as we were driving . car ran good for 2-3 miles then gave a hestitation and started running bad and code agian. would not have no response then half a mile later back to normal

gillbot

iTrader: (27)

check to be sure you are getting good spark on all cyls. Something is randomly causing all cyls to not fire. P0300 is harder to trace because it's usually random and in all cyls not a specific bank or cyl.

What do your o2 readings look like (high or low millivolts)? LTFT and STFT's high or low?

Last time I had a p0300 code, it was a loose connection on the main harness that fed all the coils.

gillbot

iTrader: (27)

I missed this post. You need to find out why that LTFT is at 25%.

Eiyse98ls1

if the o2's were bad wouldnt it set a code for bad o2's and not the random engine misfire? a freind of mine the works for chevy said i can be my front o2's or fuel injector problem. y would these set the random engine misfire code?

thanks

Pendragon

iTrader: (1)

My Quess would be an o2 problem, its putting in too much fuel and choking the motor out. so there for it cant fire right and so you get a misfire.