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Discussion Starter #1
Im a noob to the site but have had my cobalt for awhile. I have a 2006 ls 2 door with 59998 miles. Recently I've been having this p0300 code pop up but its only in the morning about once a week,I have the elm327 Bluetooth scanner and the torque app and I've watched it closely and have even recorded a 25 mile logging in which each cylinder missed about 16 times. So far I've tested cylinder pressure and its fine,pulled fuel rail and cleaned injectors individually by soaking inlet with seafoam,checked fuel pressure and its exactly where its suppose to be, this is kinda driving me nuts because the cars running great,I feel no miss at all. I have ordered a new icm and coils and I should get then by tomorrow but thought maybe someones had this headache and can lead me in the right direction in case the icm and coils don't work. thanks in advance.BTW I also put ac delco iridiums in thinking that would help but the only thing that I've noticed is that my car starts a split second after I hit the key, instead of crank crank crank vroom its more like cra-vroom...lol
 

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put the coils on and then let us know how it works. if you have the big one piece coil then its extremely common to have it act up.
 

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Yeah its the big one piece deal,I think my problem is that my hoods scoop opening is letting water just slosh over my motor when it rains because I didn't have this issue until I bought this hood at the beginning of spring. Thanks and I'll let you know.
 

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Yeah that might be it, i dont think water is supposed to just "slosh" over the motor :p i know some water is ok, but not too much. did your hood come with inserts to plug the scoop in the rain? i know some do
 

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Yeah its somewhere in the abyss that my garage has become. Im actually making a clear fiberglass insert that I'll tint then I'll put my knight rider light behind it. And I put on new coil and icm and haven't had the code pop up yet,and if it doesn't within a week im gold. Now its just a waiting game.
 

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what scoops? mine doesnt have scoops
 

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Yeah its somewhere in the abyss that my garage has become. Im actually making a clear fiberglass insert that I'll tint then I'll put my knight rider light behind it. And I put on new coil and icm and haven't had the code pop up yet,and if it doesn't within a week im gold. Now its just a waiting game.
I think thatll look pretty bada$$ man, youll have to put up some pics when its done :)
 

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Discussion Starter #8
Yeah for sure,but first I gotta figure out how to post pics! Lol
 

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i believe you can use photobucket and use the img portion to post them
 

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DTC P0300
System Description
The powertrain control module (PCM) uses information from the crankshaft position (CKP) sensor and the camshaft position (CMP) sensor in order to determine when an engine misfire is occurring. By monitoring variations in the crankshaft rotation speed for each cylinder, the PCM is able to detect individual misfire events. A misfire rate that is high enough can cause the 3-way catalytic converter (TWC) to overheat under certain driving conditions. The malfunction indicator lamp (MIL) will flash ON and OFF when the conditions for TWC overheating are present. If the PCM detects a misfire rate sufficient to cause emission levels to exceed mandated standards, DTC P0300 will set.
 

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Discussion Starter #12
Well so far so good,no codes so far.....knock on wood! Just got my 3 gauge pillar and a/f gauge. what other gauges could I use.

---------- Post added at 02:53 PM ---------- Previous post was at 02:03 PM ----------

I was thinking crank and cam sensor so I put a bottle of marvel mystery oil in the crankcase to desludge everything and the p0300 hasn't came on since!
 

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Discussion Starter #13
Spoke too soon! Rrrrrr,this code is driving me bat shit! It only sets when I first fire it up after sitting,but only once a week. so thats open loop right? Hmmm I'll have to clean the maf again,freakin k&n oil.
 

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Discussion Starter #14
Solution found: replaced all injectors and everything's gravy baby! Also cut dlp tv plastic screen to fit scoop hole. That shimmer effect will make my knight rider light look sweet shining through.
 

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Since it is a six year old car...and if you haven't done these things yet I would:

Fuel system treatment...

Fuel filter change...

Seafoam it too.
 

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Discussion Starter #16
Already did fuel filter,and treatment is a monthly thing. When I pulled injectors I sprayed seafoam in the ports and cleaned valves,then I turned engine over till the closed valves dumped the seafoam ion pistons and let it sit an hour or so then cranked it over and drove it while fogging the neighborhood.
 

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You didn't put the bottle in while it was running?

Like, half through the brake booster line, 1/4 of it in the oil and the other 1/4 in the gas tank...?
 

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Discussion Starter #18
I did it that way a few months ago,but since I had direct access to the ports I had a bottle of the spray seafoam and sprayed the valves directly and then turned over motor to open valves that were closed and let it all wash down into the cylinders and let it sit on the rings for about 2 hours then fired it up and rev'd it till it would idle by itself then drove it on the highway,opened it up in 1st,2nd,and third to clean out whatever was left in there. still running beautifully!
 
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