#7 misfire on my 2002 Dodge Ram 1500 4.7 replaced with ne...

Q: #7 misfire on my 2002 Dodge Ram 1500 4.7 replaced with new spark plugs nd replaced coil still getting error

asked by on October 22, 2017

Replaced my lower radiator hoselower radiator hose,After that I started getting a #7 misfireWhen ahead and replace that spark plug along with my coil’s and it still coming up as a number seven misfire and my truck now has, no acceleration it doesn’t run as smooth as it used to it runs rough and it smells like gas at times because I have a hard time starting and also smells like radiator fluid

My car has 134000 miles.
My car has an automatic transmission.

Check compression in that cylinder to rule out a mechanical issue such as stuck valves or very low compression. Another possibility is a vacuum leak around the intake to that one cylinder. If so, that can cause a misfire. If the lobes on the camshaft are worn, that can cause a misfire and other inefficiencies as well. I would first check for a vacuum leak. If no leak, secondary firing patterns on the misfiring cylinder should be examined on an oscilloscope. The waveform will help narrow the potential causes to fuel versus ignition. Another possibility is the misfire is due to intermittent faults in the injector and/or ignition components so although these components appear to be in spec during static testing, in fact they are not reliable and are later, in service, operating intermittently. Finally, the ignition and fuel driver circuits in the PCM for the misfiring cylinder could be faulty; that is the absolute last thing to test though unless you happen to have handy a known good PCM that you can substitute. If none of these possibilities pan out, you can request a misfiring diagnostic and the responding certified mechanic will get this resolved. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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