P0300 trouble code.

My car has been idling erratically, misfiring, spitting/sputtering and bucking while driving. It is running extremely rich with a very strong gas smell. I've parked the car since it started. It never threw a trouble code up until yesterday and it was a P0300 but that's the only code. Multiple random cylinder misfires. From my understanding, P030x (X being a number other than 0) will tell you which cylinder is misfiring. I hooked my SCT x4 up and data logged and sent it to my tuner. He said Lambda bank 1 (drivers side o2) was reading very erratically and it was all over the place. He told me to replace both o2 sensors and the car will be fine. I'm just wondering if anyone else has experienced this? I've seen a Crankshaft Position sensor o-ring TSB that was related to P0300 code? Thanks for the help!

I've been fortunate to not have this issue, however it would benefit the thread to state year make and engine/trans configuration along with modifications especially those most recently performed.

My 5.0 was part of that crank position sensor TSB. Some of the early 2013 5.0s didn't get crank position sensor O-rings from the factory. Mine they found by accident trying to figure out my P219 (think it was) for air imbalance in right bank. But that never throw a code. My P219 air imbalance finally got trouble shot down to a bad 02 sensor. But mine didn't have P300. I will see if I can pull out my old paper work to see what codes where on there. But P300 means multiple cylinders are randomly miss firing.

I found my paper work. My codes for a bad 02 sensor was P316 miss fire at start up, P301 cylinder 1, P303 cylinder 3, P219 air imbalance.

They first put the O-ring on as they saw my car didn't have it from factory per TSB. At least they told me it did not have the O-ring from the factory. Then cleared the codes and about 2k miles later the exact codes came back and they had to data log the car to find a 02 sensor was "lazy" at times as the paper work says.

Change the O2s and check the alt voltage.

I'm battling a similar situation.

P0305 - Cylinder 5 misfire
Misfire comes and goes

I've replaced spark plugs, coil packs, swapped 5-6 injectors (to see if it was injectors fault and the code moved), and ultimately changed my Crankshaft Position Sensor. My original one did not have the O-ring so I thought that it would be the reason of my misfires...nope!

I honestly am lost right now. How can I check for faulty o2 sensors?

joeymustang said:

I'm battling a similar situation.

P0305 - Cylinder 5 misfire
Misfire comes and goes

I've replaced spark plugs, coil packs, swapped 5-6 injectors (to see if it was injectors fault and the code moved), and ultimately changed my Crankshaft Position Sensor. My original one did not have the O-ring so I thought that it would be the reason of my misfires...nope!

I honestly am lost right now. How can I check for faulty o2 sensors?

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I am having the exact same issue! Mine only happens if I maintain revs at 4000 rpm. Subscribed.

Sad to say I'm glad I'm not the only one lol

Mine comes in mostly at startup. You can hear and feel the misfire as the car shakes and there is a easily heard "knock" coming from the engine. After about 15-30 seconds, it goes away...no shaking, no discernible knocking, and the car drives fine. Sometimes if I do a throttle blip it will come back, misfire for 10-30 seconds and go away. Sometimes it will flash the CEL, other times it will turn on and give the P0305 code. It's always P0305.

Mine is always #5 too. Changed plugs, coils, injectors, evap solenoid, crank sensor, checked compression, and cam sensors.

My bad. I just noticed this was 5.0 tech. I have a 3v.

seems like all generation of stang 05+ are having misfire and p03xx codes lately (y) wonder whats going on.

06monera96 said:

seems like all generation of stang 05+ are having misfire and p03xx codes lately (y) wonder whats going on.

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I'd take that over a stupid gas gauge that goes to empty randomly. Although I did have to chase a misfire code for a bit. Ended up being a plug.

i have a 2011 and just replaced the clutch.. oddly enough now i am getting these codes as well for both # 3 and 5. ive cleared the code checked the plugs which look good. i can run a bit then the light comes on again?/ car has only 26k on it.

Did anyone find a fix for this? I'm having the same issue.

Jasontreff said:

i have a 2011 and just replaced the clutch.. oddly enough now i am getting these codes as well

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Did you do a crank relearn after the clutch work?

TSB 21474.......published on 8-26-2010.

If you own a SCT X4 you can perform the crank relearn for Coyotes yourself....otherwise you know where you gotta go................

Hope this helps.