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Discussion Starter · #1 ·
Hey everyone, so I'm having a bit of trouble with a misfire.. I believe its cylinder #4. I did have it scanned and that is the code I got from it. The truck has been running a bit more sluggish and you can hear it backfire out of the exhaust and you can smell gas when I go hard on the accelerator. I've replaced all plugs, wires, cap and rotor, cleaned out the throttle body, and put some lucas injector cleaner in the gas. I figured it must be one of the injectors but I pulled the connector plug on each one as the truck was running and none of them seemed to be dead. I'm at a loss of what could be causing the problem, any ideas or suggestions would be greatly appreciated. It's a 97' 3.9L V6 magnum.
Thanks, Jerrot!
 

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Sounds like it could be a timing issue since its backfiring and you already done a complete tune-up.
 

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if you put bosche plugs then that'll do it..i had similar issue on my 99 3.9 and the plugs where new but pure junk. full set of champions (the oem plug) and new wires fixed it for me. mine was cyl 6
 

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Discussion Starter · #4 ·
I'll have a look at what plugs are in there now tomorrow morning, I cant remember.. hopefully thats all it is. If it were perhaps a timing issue, which i hope is not the case how would I find that out? thanks again for the help
 

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its not timing. if ur base time was off to cause a misfire it would be more than just that cylinder

if it is only one cylinder ur looking at either a plug, bad grounding wire, bad contact inside the cap for cyl-4, or ur injector is not firing.
 

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I had a 2000 jeep grand cherokee that I bought for my wife and it would do something similar but wasnt isolated to a certain cylinder. The code was for multiple misfires. I worked on it for about 6 months and it even went through 2 shops. I replaced coil packs, boots, plugs, pcm, cam sensor, crank sensor, iac valve, tps sensor, and it ended up being the oil pressure sensor was shorting out intermittently and pulling the ground from the cam and crank sensors inside the pcm, I never would have thought that to begin with. Anyways thats why I had mentioned timing cause if its only doing it under heavy throttle then a sensor could be going bad and affecting the timing but your right DRAGN94 it wouldn't be isolated to just 1 cylinder. And like DRAGN94 said it could be the plugs. If you have the autolite or champion plugs check the gap for cyl 4 and if its good try replacing just the cyl 4 plug and if you think it could be a plug wire swap the plug wire with another one on the truck and see if the misfire moves to that cylinder.
 

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Discussion Starter · #8 ·
so the truck does infact have a brand new set of the shitty bosche plugs you were talking about, im going to run out now and pick up the champion ones to match the wires. hopefully thats all ill need. ill let you know what happens with that
 

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yea the heat range on the bosche plugs are too harsh for the magnum engine. any time ive ever seen those plugs in a dodge they either knock or misfire
 

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code doesnt mean anything at this point..is the engine itself misfiring? if its not then the codes need to be cleared. unless u already did that prior to plug install

do u have a CPS code (crank position sensor)
 

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yea the heat range on the bosche plugs are too harsh for the magnum engine. any time ive ever seen those plugs in a dodge they either knock or misfire
Im not sure if it is true or not but I heard bosch plugs are oem in mainly high end imports like Mercedes cause the ignition system puts out so many volts and in a domestic vehicle there isnt enough voltage to make the plugs work properly.
 

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Discussion Starter · #13 ·
ahh im an idiot, no i didnt get the codes cleared. ill have to look for a scanner tomorrow and get that done. it does seem to be running a fair bit better though, doesnt sound as bad
 

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Im not sure if it is true or not but I heard bosch plugs are oem in mainly high end imports like Mercedes cause the ignition system puts out so many volts and in a domestic vehicle there isnt enough voltage to make the plugs work properly.
not true, yes they where founded in europe but their main lab is in southfield MI. we work with them sometimes to use their pre ignition detection equipment. basically knock that'll grenade engines

every engine made must go thru plug development to decide what heat range to use. a basic range 5 is nuetral. just depends on what the calibration and engine requires. all ignition systems are different but euro cars are the worst shitty wiring ive ever seen
 
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