x_orange90_x Posted March 12 Report Share Posted March 12 (edited) Last Wednesday I stopped at my local gas station and put $30 in the tank. 10 minutes later I noticed the idle was a little rough, and later that evening getting off the expressway it started shaking badly, making a strange sound under acceleration, and the CEL started flashing. 10 minutes later it was back to running smooth. I checked the code and it was P203 and P303. The light went off on its own the next start up and it ran fine for a couple days, then Saturday it started misfiring horribly for about 5 minutes and then smoothed out again. The same codes as before plus a P202 this time. Got it home and replaced the spark plugs and Cylinder 3 coil on Sunday. Ran really smooth and idled steady at 625rpm. Drove it yesterday for about 20 minutes with no issues. I started it up this morning and from the get go it was shaking, sputtering, and overall really rough. I backed out of the driveway and pulled forward just a few feet before deciding it wasn't going to stop so I pulled back in and parked it. At the very beginning i swore it was just bad gas and I even talked to the owner of the station a couple days later and he said no one else complained, and if his gas was bad he would've voluntarily shut down. My buddy who has worked on dozens of these engines said the P202 was likely only caused by cylinder 3 running so rough. He said if the plugs and coil didn't fix it then we would likely have to replace cylinder 3 fuel injector. He also recalled changing that exact injector on a lady's caravan after plug and coils didn't stop her misfiring. I can't afford a shop bill, and we can tackle the injector in the driveway no problem. My question is does this really sound like the issue? I still have an 1/8 tank of that gas so that's still a factor, but I'm not seeing issues with the other cylinders (besides what I stated above). Can the injector cause misfires for a short period of time then go back to normal for one or more days? If it's plugged, it's plugged. Shouldn't come and go from what I'm thinking. Could it be electrically failed and cause this? We've played with the wires and they don't change current run conditions at all. My buddy also noted how clean and like new the valves and seats looked, so there's that FWIW. I was not able to pull the codes this morning, but I imagine they are the same. Fwi, the spark plugs I just replaced only had about 10k miles on them. I replaced them last spring. Edited March 12 by x_orange90_x Quote Link to comment Share on other sites More sharing options...
2late4u Posted March 12 Report Share Posted March 12 (edited) I would def remove as much fuel as possible/and or add a dry gas additive to help before i would throw any expensive parts at your journey,,, i am assuming you have the 2.4 eng,might not hurt to throw in some new plugs as well since they are easy and cheap but if you do only use the OEM plugs..good luck and hope it was only some bad gas...........sorry just seen where you said you did just replace the plugs.oh well Edited March 12 by 2late4u Quote Link to comment Share on other sites More sharing options...
x_orange90_x Posted March 12 Author Report Share Posted March 12 16 minutes ago, 2late4u said: I would def remove as much fuel as possible/and or add a dry gas additive to help before i would throw any expensive parts at your journey,,, i am assuming you have the 2.4 eng,might not hurt to throw in some new plugs as well since they are easy and cheap but if you do only use the OEM plugs..good luck and hope it was only some bad gas...........sorry just seen where you said you did just replace the plugs.oh well 3.6L. I previously put Champions in but my buddy laughed when he pulled one out. I replaced them with NGK per his recommendation. I checked the gaps and they were all correct. I did add an octane booster and 5 gallons of premium the night I started having issues in hopes of "sprucing" up the alleged bad gas. When I got down to about 1/4 tank I put in a water remover. If it really is bad gas wouldn't I have issues with ALL cylinders, all the time? Quote Link to comment Share on other sites More sharing options...
tsteves5 Posted March 12 Report Share Posted March 12 You could swap the injector to another cylinder and see if the other cylinder starts misfiring. Then you'll know for sure if it's an injector before buying a new one. If the misfire doesn't move after swapping the injector, then try swapping the coil. I've seen bad "new" ones of these. I've had a few of the 3.6 engines. I've had misfires due to the wiring harness. In my case, the injector harness was not plugged in tight to the upstream harness. I've also had a misfire caused by a bad ECU. I was able to purchase a used/pre-programmed ECU online for a reasonable price. I had one engine with a persistent misfire that ended up being bad piston rings. A pressure leak-down test found that one. The 3.6 engine is also susceptible to the rocker arms issue. I've had this issue and it didn't cause a misfire condition because I caught it early enough, but I've read cases where it can cause a misfire issue. I'm not trying to scare you here, just listing some other causes of misfires that I've personally seen. 2late4u and larryl 2 Quote Link to comment Share on other sites More sharing options...
2late4u Posted March 12 Report Share Posted March 12 7 hours ago, x_orange90_x said: 3.6L. I previously put Champions in but my buddy laughed when he pulled one out. I replaced them with NGK per his recommendation. I checked the gaps and they were all correct. I did add an octane booster and 5 gallons of premium the night I started having issues in hopes of "sprucing" up the alleged bad gas. When I got down to about 1/4 tank I put in a water remover. If it really is bad gas wouldn't I have issues with ALL cylinders, all the time? i was just going by what you said i just put in 30 gas and then it started misfiring,, i would concentrate on bad gas before throwing money at parts... like i said add some gas treatments for water in the gas and try to run it all out and then add some injector cleaner as well i like using chevron brand myself, and like others have said switch the injector/coil to a different plug to see if the code changes of course on a 3.6 this involves a lot of work to check but would be the cheapest way to start,,, and as tsteves5 mentioned the new coil could be bad ...i have been watching a lot of you tube mechanics i follow and almost all of them have been saying lately to stay away from amazon ebay and all mail order part suppliers due to cheap chinese junk parts Quote Link to comment Share on other sites More sharing options...
x_orange90_x Posted March 13 Author Report Share Posted March 13 2 hours ago, 2late4u said: i was just going by what you said i just put in 30 gas and then it started misfiring,, i would concentrate on bad gas before throwing money at parts... like i said add some gas treatments for water in the gas and try to run it all out and then add some injector cleaner as well i like using chevron brand myself, and like others have said switch the injector/coil to a different plug to see if the code changes of course on a 3.6 this involves a lot of work to check but would be the cheapest way to start,,, and as tsteves5 mentioned the new coil could be bad ...i have been watching a lot of you tube mechanics i follow and almost all of them have been saying lately to stay away from amazon ebay and all mail order part suppliers due to cheap chinese junk parts Just finished replacing the #3 injector. Also replaced the o rings on 1 & 5 while the rail was off. Ran smooth at idle and was good on a test drive. But then again it was the other day too, so we'll see. As for the coil I got, it's a Blue Streak from Advance Auto. Made in Poland if that makes any difference. The injector I got was a Carquest Remanufactured, which was actually a Mopar part. I'll update when I have some results. 2late4u 1 Quote Link to comment Share on other sites More sharing options...
x_orange90_x Posted March 14 Author Report Share Posted March 14 On 3/12/2024 at 9:49 PM, x_orange90_x said: Just finished replacing the #3 injector. Also replaced the o rings on 1 & 5 while the rail was off. Ran smooth at idle and was good on a test drive. But then again it was the other day too, so we'll see. As for the coil I got, it's a Blue Streak from Advance Auto. Made in Poland if that makes any difference. The injector I got was a Carquest Remanufactured, which was actually a Mopar part. I'll update when I have some results. I've driven about 1.5hrs yesterday and this morning and so far it's still running great! The CEL went off on its own yesterday. It's running better now than it did before the misfires started. When we went to remove the injector it was loose/wiggly. The other two were nice and solid. My buddy says too much pressure may have been building up behind it when it wasn't working, which could have started pushing it out some. Thanks for the help guys! Off topic question: what engine/trans mount typically fails on these cars? I know I have at least 1 bad one because the engine shifts forward/backward shifting, and while driving it will jerk left slightly if it shifts too hard. Quote Link to comment Share on other sites More sharing options...
tsteves5 Posted March 14 Report Share Posted March 14 4 hours ago, x_orange90_x said: Off topic question: what engine/trans mount typically fails on these cars? I know I have at least 1 bad one because the engine shifts forward/backward shifting, and while driving it will jerk left slightly if it shifts too hard. I've had issues with all of them, but mines is a bit older (2011). Quote Link to comment Share on other sites More sharing options...
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