2006 Dodge Charger SXT 3.5L V6
Hello so one day I was on my way to work and my car was running fine got off the interstate to the stop sign and it started to shake really bad so I put my Bluetooth U-Scan in and it came back with the code P0300 (Random- Multiple misfire detected) so I stayed at work got off and started my car still shaking really bad got to the interstate had hesitation unless I got into second gear then started to run a little smoother. Next day started to diagnose this issue first started with checking for vacuum leaks, the EGR tube in the back of the air intake manifold was sucking a lot of air so got a new gasket on it still sucking a little air ( this I can fix, willing to take suggestions tho) second thing I did was check the spark plugs the right half 2, 4 and 6 look like they are functioning normally light brown/grey don’t smell of fuel but the left half 1, 3 and 5 look black, wet and smell of fuel. So I then switch around the ignition coils all three on the left for the three on the right put the air manifold back on started the car still has the code on and shaking. (Note just changed spark plugs two weeks ago did a oil/filter change and transmission filter/fluid change) Now I start to pull the wire connectors off individually to see if any coils are bad (only able to take off 1, 2, 4, and 6 coil 3&5 being under the manifold) coil 2, 4&6 all made the engine start to stall out or changed how the engine performed. Coil 1 however made no change so then I switch coil 1 with coil 4 I know was working thinking that coil 1 was bad, but no what had happen was the same result being coil 1 now worked but coil 4 did not so I switched for another coil same results. Not being able to check coil 3&5 with the manifold on and the engine running troubles me because now I can’t find out if it is the wiring harness! Any suggestions would help I bought the car not because I liked it but kind of was anticipating it to have problems randomly down the road but ended up getting a problem that is frustrating and complicated for me not a mechanic haha but working and solving my own car problems has always attracted me.
FREEZE FRAME
Trouble code- P0300
ABSLT TPS- 14.5%
ENG SPEED- 138 RPM
BARO PRS- 28.1 “HG
CALC LOAD- 45.9%
MAP- 14.8 “HG
OUT TEMP- 66 DEGF
COOLANT- 189 DEGF
IAT- 68 DEGF
IGN ADV- 14.5 DEG
ST FTRM1- -33.6%
ST FTRM2- -9.4%
LT FTRM1- 5.5%
LT FTRM2- 7.8%
VEH SPEED- 3MPH
ABS LOAD- 32.2%
FUEL SYS 1- CLOSED
FUEL SYS 2- CLOSED
REL TPS- 2.7%
THROT CMD- 2.7%
ABS TPS B- 13.7%
ACC POS D- 9.0%
ACC POS E- 4.3%
EGR ERR- 0.0%
EGR CMD- 0.0%
EVAP PURGE- 0.0%
CMD EQ RAT- 0.999
FUEL LEVEL- 93.0%
VPWR- 12.569 V
ENG RUN- 07:44
Did this happen soon after a fuel re-fill? If so, consider the possibility you got a tank of bad or water contaminated gas. If you can figure out a safe way to get a sample of the fuel in the gas tank, put it in a clear container and observe if it separate into layers over a few hours time…
If it is possible that somebody pulled a prank on you and swapped the ignition wires so they no longer match up with the correct cylinder, check for that.
I did have a full tank of gas I already have a new fuel pump from when I bought the car so gonna replace that and will get a turkey baster or something like that and deposite into a container it is possible the gas was bad at that station or someone decided to pull a prank and put something in my gas I stay at a hotel need to get a gas cap with a lock. Highly doubt the Wires got switched around on the coils they only reach to that coil being wrapped up with the fuel injector harness and being hard to reach with the intake plenum is covering it. Being said the fuel filter is actually in the fuel pump module itself I was told so that will clear the filter out the way when I go switch the pump I’ll check the gas in it. I am planning on changing out sensors as well everything is in rough condition. I am coming to a conclusion it is a fuel issues, I heard faulty purge valve can cause a vacuum leak if I am not
Mistaken. Being bank 1 is the side misfiring could be lack of fuel pressure as well I assume still few things to test I just don’t know how to test fuel pressure on this car can’t find a test port.
UPDATE on a code p2303 (ignition coil “A” secondary circuit, I notice a black box bolted the the left side of the engine (that I am calling bank 1, the misfiring side) the box is call a radio capacitor but when looking for it on auto part store under my car also says Ignition RFI Condenser it had another separate wire bolted with it assuming to ground that wire. The wire that connects onto the Ignition RFI Condenser (single wire) had a connector that was fried and the wire was exposed and moves loosely in the connector housing so I unplugged it and that’s when I got the new code p2303. So I cut the wire added a basic crimped plug( basic plug is temporary) reconnected it erased the code never came back till later this night got another one that’s similar p2308 (ignition coil “c” secondary circuit) now I would assume bank 1 left side is coils A, C & E (since its saying letters not numbers) bank 2 right side B, D & F. Still to believe it’s just bank 1 having issues with the misfiring. Tomorrow going to go back to that Ignition RFI Condenser and do a better wiring job doesn’t seem like the best I could have done wire was short to actually reach the connection comfortably so thinking it lost its connection again causing the new p2308 code gonna improve the wire more better and change few things out with the fuel system and few sensors do some more multimeter reading test again, the ones I do today seemed okay. What I did today was test the resistance of the coils, coil connectors and spark plug put a new intake plenum gasket on as well as that damn EGR tube going into the back of the intake plenum had put two of those gaskets on still getting a small air suction from it. Did clean the carbon build up on a lot of places as well. Car is starting to sound, misfire and shaken worse at idle every day(when I do rev the RPMS up kind of smooths out but can tell it’s still having multiple misfiring) hoping I don’t mess up the cat converter even those the whole exhaust from the headers to the exhaust tip look like there in bad condition trying to start with the small stuff first already know a lot needs to be done but I have the time to fix it after work and on weekend.
It depends on what that capacitor is for. I’m guessing it is a radio interference suppression capacitor. It’s purpose is to filter out electrical noise before it can prevent you from hearing Jimi Hendrix perform “All Along the Watch Tower” on your favorite classic rock FM station. If that’s the purpose, if it failed open it wouldn’t likely cause misfires. But it might cause static on your radio. If it failed shorted, no telling what that would do, probably blow a fuse.
The other potential purpose, it could be a required part of the ignition system. If you remember the now-obsolete contact-points style distributor, that design had a capacitor attached to the distributor. It helped produce the desired sparkplug input waveform so the spark plug fired correctly. Today’s electronic ignition systems replace the points with a transistor, but still require that capacitor. If that capacitor fails, it will cause misfires on either the older points style or the modern electronic ignition style. That capacitor was under suspicion on my points-contact style early 70’s truck’s ignition system last summer, but upon testing it turned out to be good. That problem then was an arcing high voltage wire instead.