I will start by saying I have searched. I have read. I am posting to see if my specific combo of things might help with the diagnostics or a starting point. apologies in advance. i didnt see these specific things and it seems these codes have a ton of different causes.
now. for whats up. I just purchased this jeep wednesday night. looked at many and finally settled on this one. 2003 rubicon. 160k miles. manual trans. 4.0L. the only issue it seemed to have mechanically was axle lockers not working and you have to prime to fuel to start it up (use the key to get the fuel pump to run a couple times). after you do this it starts up fine. idles fine. runs fine. if you shut it off and start it right back up its fine. if you go in the store, shop around, come back. you need to prime again. PO said his thoughts where vacuum leak (he said why he thought this.... i remember it sounded reasonable... but I dont remember what it was... I just remembered the hilights... needs priming... check for vacuum leaks first to fix)
so anyway. I drove it home from the seller. about an hour drive. ran over something and got a flat. (this is my type of luck) so it stayed home yesterday. took it today for a patch and run a few errands. while out today check engine light came on (steady.. not blinking). so when I got home I connected my scanner and I got the following codes:
Current faults:
P0300 - Random/multiple cylinder misfire detected.
P0301 Cylinder 1 misfire detected.
P0455 - Evaporative emission control system leak detected.
and finally...
Pending fault:
P0302 cylinder 2 misfire detected.
my first wonder here was "did the previous owner just swindle me? clear the codes and let me ride off?" however. he was honest about everything else. even the axle locks not working which he could have easily kept to himself and most people wouldnt know until its too late... anyway... I tried to clear the codes myself to see how long until they pop up again. (idk if its right... but its my go to for a new code... my way of seeing if its some weird one off thing... or a reoccuring issue). and it basically doesnt clear. check engine light stays on. check codes again and they are there. so... i figure he couldnt have cleared them and kept them away while I test drove and then drove an hour home.
so... my question here is... could there be something that matches the misfire codes with the priming fuel issue that gives an indicator for first try? what about that evap code exactly? googling it seems like its kind of a vaque code (truth is they all do... wish I had an actual diagnostic scanner.. but thats a pretty penny). I figure i would ask because.. on one hand... I dont want to chase down a vacuum leak if that actually seems like its unlikely here. on the other.... no need to spend $200 replacing coil rail and plugs first if these signs lean towards vacuum leak ( which, BTW, the coil rail does look somewhat new. so at least its not the original and this has obviously had a tune up...... seemingly in recent history. though exact time would be unknown). seems like the priming and misfires could be related to a fuel delivery issue? but then... it would have me wondering why the first cyl is taking the brunt of the misfiring?
also. I wont say I have an ear for saying yes or no to a little difference in sound given that i am not familiar with this motor and only drive it for an hour prior (with the top back and other noise for good measure). but I can say... that driving it today after the light... there was no backfireing or poping or anything obvious going it. it idles steady at about 800rpm and if this light wasnt on... i wouldnt have thought any issue (but again... 1 cylinder could be completely dead and my ear wouldnt know without having a good reference for this motor prior... I noticed a misfire on a truck once before but I had driving it daily for a couple years and was very used to its sound. im no mechanic. I do most of my own vehicle repair work... but... there is plenty i dont know.
now. for whats up. I just purchased this jeep wednesday night. looked at many and finally settled on this one. 2003 rubicon. 160k miles. manual trans. 4.0L. the only issue it seemed to have mechanically was axle lockers not working and you have to prime to fuel to start it up (use the key to get the fuel pump to run a couple times). after you do this it starts up fine. idles fine. runs fine. if you shut it off and start it right back up its fine. if you go in the store, shop around, come back. you need to prime again. PO said his thoughts where vacuum leak (he said why he thought this.... i remember it sounded reasonable... but I dont remember what it was... I just remembered the hilights... needs priming... check for vacuum leaks first to fix)
so anyway. I drove it home from the seller. about an hour drive. ran over something and got a flat. (this is my type of luck) so it stayed home yesterday. took it today for a patch and run a few errands. while out today check engine light came on (steady.. not blinking). so when I got home I connected my scanner and I got the following codes:
Current faults:
P0300 - Random/multiple cylinder misfire detected.
P0301 Cylinder 1 misfire detected.
P0455 - Evaporative emission control system leak detected.
and finally...
Pending fault:
P0302 cylinder 2 misfire detected.
my first wonder here was "did the previous owner just swindle me? clear the codes and let me ride off?" however. he was honest about everything else. even the axle locks not working which he could have easily kept to himself and most people wouldnt know until its too late... anyway... I tried to clear the codes myself to see how long until they pop up again. (idk if its right... but its my go to for a new code... my way of seeing if its some weird one off thing... or a reoccuring issue). and it basically doesnt clear. check engine light stays on. check codes again and they are there. so... i figure he couldnt have cleared them and kept them away while I test drove and then drove an hour home.
so... my question here is... could there be something that matches the misfire codes with the priming fuel issue that gives an indicator for first try? what about that evap code exactly? googling it seems like its kind of a vaque code (truth is they all do... wish I had an actual diagnostic scanner.. but thats a pretty penny). I figure i would ask because.. on one hand... I dont want to chase down a vacuum leak if that actually seems like its unlikely here. on the other.... no need to spend $200 replacing coil rail and plugs first if these signs lean towards vacuum leak ( which, BTW, the coil rail does look somewhat new. so at least its not the original and this has obviously had a tune up...... seemingly in recent history. though exact time would be unknown). seems like the priming and misfires could be related to a fuel delivery issue? but then... it would have me wondering why the first cyl is taking the brunt of the misfiring?
also. I wont say I have an ear for saying yes or no to a little difference in sound given that i am not familiar with this motor and only drive it for an hour prior (with the top back and other noise for good measure). but I can say... that driving it today after the light... there was no backfireing or poping or anything obvious going it. it idles steady at about 800rpm and if this light wasnt on... i wouldnt have thought any issue (but again... 1 cylinder could be completely dead and my ear wouldnt know without having a good reference for this motor prior... I noticed a misfire on a truck once before but I had driving it daily for a couple years and was very used to its sound. im no mechanic. I do most of my own vehicle repair work... but... there is plenty i dont know.
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