I have a misfire on cylinder no.3. My truck shakes alot during idle, at about 1000RPM the its much smoother. and if i drive really slow the whole truck shakes, like its missing. It is incredibly unpleasant to drive.. but since im working full time and have 20 mile commutes, the shaking gets old. Ive tried plugs and wires, Checking vaccuum leaks, the plenum is fixed, doesnt use much oil, cylinder doesnt seem dead becuase if i unplug it the engine runs like crap, injectors are clean and ive moved them to check.. my next guess is maybe O2 sensors, a bad IAC valve, or a sensor, since i have no other codes other than a (inefficient catalytic converter code" that pops up if i drive crazy. truck seems to run the same other than the shuddering at super slow speeds and the crappy idle.

Any help?

 

If your truck has the original 02 sensors with over a 100.000 miles on them, then there bad and should be replaced. I would also recommend that you pull the throttle body off the engine and give it a good cleaning, including the IAC valve. Also check the map sensor and throttle position sensor, if there bad they can cause the problem your having.

 

Disconnect the O2 sensor, go for a drive, see if it's any better. (will set a code.)

 

Compression or leak-down test performed on that cylinder?

Unfortunately, my first misfire turned out to be a cracked cylinder head and burned valve.. I would definitely check it.

Oh and what plugs do you use? Stick with standard copper plugs. I've had the most success with the factory spec'd Champion units.

JT

 

I took it to work today and hooked it up to a live data stream scanner, The misfire was consistent and only happened at idle. turns out the last time i did the plugs a few threads got jacked up and only half the plug was going in. i figured this out after spraying liquid grease in the metal shroud and it bubbled when i turned the motor over. I found a tap in the shop i work in and rechased the threads, and to my suprise it threaded in all the way, and the motor ran MUCH better.

Im ordering new plugs and wires this week.. But im extremely relieved knowing my MPGs should increase ALOT, and i can actually pass people

Now i just have to weld up a small exhaust leak thanks guys

 

Thats a dumb *** move lol cant believe the plug didn't go flying out and if it wasn't for that exhaust leak you would of been able to hear the problem.. I remember I put a disc break pad on backwards before drove it a couple miles and it got louder and louder lol went home and flipped it over and kept truckin lol

 

Lucky Guy...Good Job!
Don't forget about TSB-18-48-98 while your in there working on plug wires.
http://dodgeram.info/tsb/1998/18-48-98/18-48-98-v8.htm
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