Hello, I am new to the forum, and I hope some of you will be able to offer me some advice. I have a 2005 Dodge Caravan with 86,500 miles on it. I was getting some fault codes, P0301 (cylinder one misfire), as well as P0456 (leak in the evaporative system). So far here are the new parts that I have fitted: new spark plugs, new leads, new coil pack, new fuel cap, new IAT sensor (intake air temperature), PCV valve (positive crankcase ventilation), EGR valve, MAP sensor (manifold absolute pressure), 6 new injectors, and a purge valve. I am still getting a cylinder 1 misfire?? With all of these new parts, the car is definitely running a lot better and for the most part feels very smooth, but I can feel that a cylinder is occasionally not firing. I have checked the vacuum hoses and they all look good. I am at a loss as to what to repair/replace next. The only thing I have not done is check the compression in each cylinder compared to the number one cylinder, in case there is something with the cylinder head gasket or a valve. Please help. Thank you! Joe

 

I forgot to mention that I also replaced the TPS (throttle position sensor)

 

I felt as though I was running out of options, and although there were no signs of a leaking head gasket (oil in the water, poor performance constantly or at least until warmed up, etc), I felt I should perform a compression test. So I went to my local Autozone and borrowed a compression checker (a fantastic service btw). When I removed the relatively new spark plugs, I noticed the problem right away. The gap on the number one spark plug was way too small. So, I re-gapped it, and performed a compression check anyway, since I had the tool. All six cylinders checked out fine, within 5 psi of 160psi. I don’t regret putting in most of those parts, as the new injectors (only $36 for all 6!) made the car run smoother, the PCV valve was long past it’s recommended 60,000 miles/60 months period, the new fuel cap eliminated the EVAP fault code I was getting, and of course, the plugs/wires/coil pack were all needing to be replaced. So, a happy ending to this saga, thank you DodgeForum for the moral support, I hope this helps someone else!