I have a P0303 error.... I did some checking and I have a blown head gasket...hoping not a cracked head. I bought a tester and checked the radiator for exhaust and it came up positive. Taking into a friends shop, he will replace both head gaskets and have the head worked for $750 so I can't complain.

 

ive got a 2005 3.7 Dakota misfire every month ive replace a coil different every time now ive got codes 300 and 303 misfire and #3 coil dont want to replace a new set of six coils what else can i be missing all new plugs also

 

How did you diagnose this problem, CULOSE? Was the engine making noise? I have a 98 Caravan with a 3.3L V6 that runs fine until it warms up and then it begins to misfire - but only when throttle is applied and above 1900 RPM or so. It has me baffled. YouTube video here if you care to see it.

 

I've been having a misfire issue with my 4.7 and running Seafoam through the fuel system and vacuum line seems to have cured it for the time being. I have a thread going right now if you want to read through it.

Sometimes an injector can be clogged and the Seafoam can help break that stuff up and it will begin to run better. I put some in the oil as well and it may have cleaned valves or ports that had build up. Anyway, it worked. You may have a similar problem. After I ran everything through it took 50-75 miles to go away, assuming it took some time to break down build up and clean everything out.

 

I have the same issue, replaced plug,coil,injector,and cam possition sensor. crank sensor is new. Im thinking Cylinder that works in conjuction with Cylinder 3. need to know which cylinder works in conjunction with cylinder 3. just to note that I have no more oil in wire harness, which it did have at one point. changed oxygen sensor upstream on bank 1. also did Compression test as well and holds at 150. it should cause after all piston and rings are brand new as well. did a leak test on heads as well. incase that question was asked.

 

If you have a blown head gasket in a 4.7 have fun paying to have that done i just dumped a ton of money into head gaskets heads timing chain sliders plugs injectors an coil packs it sucks 2850 dollars later.

 

first of all guys if you have a dodge or chrysler don't bother bringing it to a mechanic to diagnose it. Just turn the ignition on three times with out starting it and the code will come up were your mileage is, it will say done when it's done. If you have a miss fire code like i did, you should change you distributor cap and rotor. It's suppose to be done every 24,000 miles! I would do it at least every 40,000 miles. My truck was running a little rough and would stall some times. I changed the distributor cap and rotor for $20 and my truck ran smoother and the code was gone. If you have a rough idile, that should solve the problem also.

 

I have a 5.7 Hemi ram that has the same code. I ran a compression test to find I had little to no compression. Spark plugs was filled with oil. Also my air box has oil in it. Bad piston rings is the case. Run a compression test on all cylinders. If its only that one cylinder that's low. Only replace that one piston and rings. You might want to change the headgasket while you have it all apart. Don't let these repair shops fool you into getting another motor. A lot of shops don't want to break down a motor. Find a shop that can repair the problem you might come out a whole lot cheaper.

 

I have a p0302 misfire and truck will not pass smog. I've tried changing spark plugs, tested all coils, switched coils around, opened the valve cover but the rocker arm was in place. Now I'm going to try the seafoam to see if it works. Any other suggestions would be appreciated. I'm getting a little desperate because my smog is due this month. But I also don't make to make a bad call (like quarterbacks) because I'm under pressure.
Thanks

 

After many months of frustration, I managed to resolve my misfire detected code by re-installing my OEM crankshaft position sensor after replacing it with an aftermarket sensor during my many attempts of troubleshooting. I had to install/reinstall the OEM crankshaft position sensor to get it to go away - it took some fiddling. I should note that I did this after correcting my real problem, which was a cracked flex plate. However, I dealt with the misfire for months after repairing the flex plate, only to find out it was my crankshaft position sensor.