people w/ a P0300 code come on in
#1
TECH Fanatic
Thread Starter
iTrader: (12)
Join Date: Jan 2006
Location: sw fl.
Posts: 1,899
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
well i have a bolt-on 01 z28 with NO CATS and its been running great... i changed the plugs and wires about 15k ago with NGK tr55's and MSD 8.5mm wires (when i did my headers) along with bosch 13111 o2's.. then the other day i started to get a slight miss at idle and then the SES started flashing then after a minute or so it turned solid...
i went out of town for a few days and when i started it back up it ran fine w/ no lights or nothing... this morning it was running great and the light came on, it blinked for a minute or so then went solid, and after work it came on solid right at startup
i drove it to discount auto for a free scan and it came up w/ p0300 (random/multiple cylinder misfire detected)
after that i drove it for another 15 minutes or so testing how it idled, how it did just cruising and also at WOT.. everything was nice and smooth and i got no lights.. i have noticed that ive been using up some oil between changes, but there is no smoking.. anybody else have similar symptoms (ive searched but couldn't find exactly what i was looking for)
i have stock coils so hopefully its as simple as a weak coil
they are also stock injectors would buildup in the injectors do this at all??
im going to check all my wires to make sure none are loose or burnt, and im also going to check my grounds..
i hope its not a broken valve spring or bent pushrod (i doubt it is since it still runs great and doesn't smoke or backfire and i havnt seen a decrease in fuel economy)
any ideas/help/suggestions would be greatly appreciated
i went out of town for a few days and when i started it back up it ran fine w/ no lights or nothing... this morning it was running great and the light came on, it blinked for a minute or so then went solid, and after work it came on solid right at startup
i drove it to discount auto for a free scan and it came up w/ p0300 (random/multiple cylinder misfire detected)
after that i drove it for another 15 minutes or so testing how it idled, how it did just cruising and also at WOT.. everything was nice and smooth and i got no lights.. i have noticed that ive been using up some oil between changes, but there is no smoking.. anybody else have similar symptoms (ive searched but couldn't find exactly what i was looking for)
i have stock coils so hopefully its as simple as a weak coil
they are also stock injectors would buildup in the injectors do this at all??
im going to check all my wires to make sure none are loose or burnt, and im also going to check my grounds..
i hope its not a broken valve spring or bent pushrod (i doubt it is since it still runs great and doesn't smoke or backfire and i havnt seen a decrease in fuel economy)
any ideas/help/suggestions would be greatly appreciated
#2
Staging Lane
iTrader: (1)
Join Date: Apr 2004
Location: NC
Posts: 58
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Check those wires real good. That message is really a generic message meaning there are a ton of things that could be causing it. Last time I had it, my accident I happened to notice that one of my wires had layed up on one of the exhaust manifolds. I happened to have the hood open in shaded light and the spark jump caught my eye. Based on the fact that you just replaced wires, I would look there first.
#3
TECH Fanatic
Thread Starter
iTrader: (12)
Join Date: Jan 2006
Location: sw fl.
Posts: 1,899
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
well its been about 15,000 since i replaced um.. im going to be replacing the wires, plugs, and injectors in a few weeks (doing a turbo install) so hopefully one of those is the problem.. ill check under the valve covers to make sure nothing is bent/broken
#4
TECH Fanatic
Thread Starter
iTrader: (12)
Join Date: Jan 2006
Location: sw fl.
Posts: 1,899
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
well its gotten worse.. the light is on 24/7 and misses more at idle then before.. still runs strong under throttle though...
fuel mileage went down a few mpg and i can smell unburnt fuel from the exhaust...
still no smoke or backfiring so im pretty sure its an ignition issue and nothing involving the valve train.. im changing the plugs tomorrow so hopefully that will fix the problem (fingers crossed)
fuel mileage went down a few mpg and i can smell unburnt fuel from the exhaust...
still no smoke or backfiring so im pretty sure its an ignition issue and nothing involving the valve train.. im changing the plugs tomorrow so hopefully that will fix the problem (fingers crossed)
#5
TECH Fanatic
Thread Starter
iTrader: (12)
Join Date: Jan 2006
Location: sw fl.
Posts: 1,899
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
hmm doesnt look to good right now...
all the plugs on the drivers side look perfect, but on the pass. side the first 3 are completly black
i havnt taken the back one out yet but im assuming it will be too ![Sad](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_sad.gif)
any ideas on what this could be... all the plug wires were fully on and were not burnt cracked dried or discolored...
what could be causing the entire side to do that??
all the plugs on the drivers side look perfect, but on the pass. side the first 3 are completly black
![Icon Eek](https://ls1tech.com/forums/images/smilies2/icon_eek.gif)
![Sad](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_sad.gif)
any ideas on what this could be... all the plug wires were fully on and were not burnt cracked dried or discolored...
what could be causing the entire side to do that??
#6
TECH Senior Member
iTrader: (24)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
when the light is flashing it means that damage is happening to your cats, usually unburnt fuel going down stream. anyways the msd wires you need to be really close to make sure that there are two clicks. and those two clicks are solid and not weak *** clicks. on my friends car, he had the EXACT same problem. i already knew it was plug related since he had done plugs a while back. anyways when we got stranded for the 3rd time we started to pull the plugs out and the way he was pulling them out was by the wire and not the boot. when he got them off we could BARELY see the strap that goes into the coil, it had been buried deep inside of the boot. we ditched the MSD's and got some Taylor wires that another friend had in the back of his trunk. After that everything went back to normal and no problems
#7
TECH Fanatic
Thread Starter
iTrader: (12)
Join Date: Jan 2006
Location: sw fl.
Posts: 1,899
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
my cats are a few hundred miles away in texas, i sold them when i indtalled my LT's and ORY lol.. and i the wires were all the way on.. i changed out all the plugs and fired it up, it isnt missing anymore and the is non SES light on..
im hoping that was the problem, i guess ill find out in a few days
thanks for the info
i also plan on switching to taylor wires in a few weeks anyways..
im going to have the valve cover off so im gonna do pushrods and rockerarms while im in there so ill find out if one is bent
im hoping that was the problem, i guess ill find out in a few days
thanks for the info
i also plan on switching to taylor wires in a few weeks anyways..
im going to have the valve cover off so im gonna do pushrods and rockerarms while im in there so ill find out if one is bent
Trending Topics
#8
Banned
iTrader: (10)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Originally Posted by reject
when the light is flashing it means that damage is happening to your cats, usually unburnt fuel going down stream.
And yes, you are correct that its the raw fuel that causes the damage, and what the flashing light is trying to alert you to so you can get service ASAP.