420A 2gNT Code P0300

[MurkinStock]

Looking to bounce an idea off you guys. I just bought this car(97 eclipse gs) pulled CEL codes, fixed o2 sensor code and now i'm getting the the p0300 code. Fuel system has been ran through and vacuum lines all checked. I ran some sea foam into the vacuum system and as it usually does it started smoking. As i'm standing there i noticed smoke coming from where the header meets the next pipe that houses the upstream o2 sensor. My question is, if there is no gasket or a bad gasket where these two meet could this be causing the exhaust system to pull in air and mess with the o2 sensor reading thus triggering the random misfire because the computer cannot keep up with the fluctuating air intake through the bad gasket?

Thanks for any help!

 

[sbz0kgx]

If I'm not mistaken, I believe p0300 is a random misfire code.

 

[MurkinStock]

it def is, was wondering if the bad exhaust gasket right before the o2 sensor could be causing a misread in the fuel to air ratio and telling the computer to compensate causing it to misfire. Is that a thing? hahah

 

[sbz0kgx]

Thanks for the speedy reply RadDsm. According to the list here is where I have gotten.

•Faulty spark plugs or wires - -replaced
•Faulty coil (pack) - -replaced
•Faulty oxygen sensor(s)
•Faulty fuel injector(s)
•Burned exhaust valve
•Faulty catalytic converter(s)
•Stuck/blocked EGR valve / passages
•Faulty camshaft position sensor
•Defective computer -checked no problems.

 

[sbz0kgx]

Id start with the easier stuff first. Check plugs, wires, and coil packs. Just my 2 cents, I'm am not an expert I did some research and there are a few possible causes "listed above"

 

[MurkinStock]

Ha me either! Appreciate the help though. So i went ahead and put the exhaust gasket on while i was down there i went looking for an oil leak. I pilled the oil pan and that wasn't it, i then saw that one of what I'm assuming to be is an oil pressure sensor half way screwed in and drenched in oil. In my pursuit of trying to reach behind the engine and tighten it with the incorrect tool I broke the yellow wire that goes into it. Fixed that, put everything back together, added the oil and proceeded to start the car only to have it turn over and not start! Of the symptoms that you listed do you think one or many could cause this?

Plug wires replaced
o2 sensor replaced
fuel pump replaced
fuel filter replaced
spark plugs checked and are fine

 

[sbz0kgx]

Did the no start happen before or after you replaced the fuel pump and filter?

 

[MurkinStock]

The kid i bought the car from said it was replaced along with fuel pump, fuel filter, and i think he said fuel pressure regulator. yesterday I got underneath it and replaced the exhaust gasket at o2 sensor, engine mount and found the oil pressure sensor in the back of the block was half way screwed in causing an oil leak. attempted to screw it in (pain in the ass to get to) ended up snapping the wire and had to re-wire it. There's only one yellow wire going into that right? while i was down there i noticed that the sensor, about the same size as oil pressure sensor and more towards passenger side of the block, has some pretty horrible wiring done on it. Not sure what this sensor is, maybe knock sensor? Either way, if somehow i knocked theses wires lose could it case a no start? Also, I don't know if this helps at all but when I attempted to start it the rpm gauge doesn't show the engine rotating. Not sure if these eclipses do that or not. Again, thanks for the reply!