Crankshaft sensor causing misfire

Tiny
MALLORYPCOE
  • MEMBER
  • 2002 DODGE DURANGO
  • V8
  • 4WD
  • AUTOMATIC
  • 138,000 MILES
Hello, right now it is currently throwing six codes. I have been chasing a misfire all over this engine and cannot seem to get it under control. It is throwing a cylinder five and six misfire as well as a random misfire. It is also throwing and cylinder two and seven fuel injector circuit malfunction code. Everyone has said that the problem is occurring from the crankshaft sensor going bad. The original misfire was two and four, then five and seven. Now this! Please help? Also, if you go to drive after starting the engine as soon as you go into gear the engine stalls and you have to hold the gas pedal down all the way to get it to start and you have to keep pressing the gas until the engine finally idles on its own. What is going on?
Tuesday, January 9th, 2018 AT 11:55 AM

3 Replies

Tiny
STEVE W.
  • MECHANIC
  • 14,526 POSTS
I would start checking the wiring harness on top of the engine and where it drops over the heads in the rear for damage. The injector circuit codes would be my first target. Poor injector control or a bad injector(s) will cause misfires.
I would also check the actual running fuel pressure and look for vacuum leaks around the intake manifold. If you have access to a scope it would be a good idea to scope the ignition firing synced to the crank and cam sensors. I also doubt that it is a bad crank sensor. They are usually good or bad on that engine. No in between area.

When was the last time it had the plugs changed? The 4.7 uses common copper core plugs that need to be changed every 35,000 or so, they do not like any of the other high life types and will cause odd misfire patterns if they are used. The 3.7 is the same way.
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Tuesday, January 9th, 2018 AT 1:02 PM
Tiny
MALLORYPCOE
  • MEMBER
  • 2 POSTS
Hi, Steve thank you for answering so quickly. The spark plugs and all the coil packs were changed less than 2,000 miles ago after the engine overheated and burned them all. My catalytic converter is plugged severely causing the engine to constantly overheat itself until it reaches a certain temperature and cool itself down. I have a lot of problems with this vehicle but am trying to fix it one thing at a time. I believe my valves are burnt as well from when the engine overheated and eventually stalled the truck and made the transmission very sluggish and hesitant to moving at all. At the point I am ready to just get a new vehicle.
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Tuesday, January 9th, 2018 AT 1:12 PM
Tiny
STEVE W.
  • MECHANIC
  • 14,526 POSTS
The 3.7 and 4.7 are very sensitive to overheating, they usually warp the heads and have valve seat issues from it. The only real cure is to overhaul or replace the engine.
From your description it sounds like you need transmission work, converters, and major engine repairs. Even if you DIY all the repairs and went for a used engine you will be putting a lot of money in it. If it were mine I would very seriously look for a different vehicle unless the rest of that thing is in very good shape.
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Tuesday, January 9th, 2018 AT 3:22 PM

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