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Dodgerench
Dodgerench, ASE Certified Technician
Category: Dodge
Satisfied Customers: 3399
Experience:  30+ years Dodge/Chrysler exp., ASE Master with L1 certification. Driveability/ combustion specialist
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Own a 2002 dodge ram truck it seems to cut out when I

Customer Question

own a 2002 dodge ram truck it seems to cut out when I accelerate from a dead stop and while crusing if I give it throttle seems normal starts fine and idles at 1100 rmps not using any excessive fuel engine has 13200 not sure whats up the weird thing is it always have the cutting out issue
Submitted: 2 months ago.
Category: Dodge
Expert:  Dodgerench replied 2 months ago.

Hi, my name is Ed. Welcome to JustAnswer!.

If - by cuts out - you mean that you have a momentary or repeating misfire, chances are good that it's being caused by a flashover condition at one or more spark plug-coil assemblies. Each cylinder gets its own ignition coil that's installed directly atop the spark plug, shortening the path that secondary ignition (spark) has to take. That's all good until electrical resistance needed to jump the spark plug gap exceeds that of just having the spark leak down the outside of the plug. Each time spark "flashes over" the spark plug, it will etch a little bigger track in the upper spark plug insulator and inner coil boot, making it just a little easier for the next spark to follow the same path. Flashover tracking is usually pretty load-dependent in its earlier stages, preferring to leak to ground under circumstances like you've described, but not be felt otherwise. When it gets bad enough, misfire will happen almost continuously, setting a code and turning the MIL on.

A visual inspection or replacement of the spark plug set would likely turn up the offending parties. Any black mark on the spark plug upper insulator that won't scratch off with a fingernail IS flashover tracking and there's no fix for it. You need to replace the plug and coil at the same time or the tracking left in the other part will just cause immediate failure of the new one. These engines run a very long time on a set of plugs and it becomes easy to forget that we used to replace them at 30,000 miles (as is recommended with the 4.7 still). But they'll just keep plugging along until flashover begins and that could be well over 100K miles worth of wear, which is considerable.

If you happen to have a CHECK ENGINE light illumination now, you likely have a code relevant to the problem stored and waiting to be read. Let me know.

Another situation that can better be called cutting out can be caused by a wiring abrasion that happens on the passenger side-top-rear of the engine, where a large wiring harness trunk drops down from the wiper cowl and disappears behind the cylinder head. It's right back there - where you can't see very well - that a sharp machined edge of the cylinder head can gnaw into the wiring loom, shorting selective circuits in circumstances such as yours.

To help diagnose, start the engine and pop the hood. Place a stool on the passenger side fender area.

Reach over the air cleaner duct and lightly tug forward and down on the wiring harness. If the engine exhibits ANY displeasure with what you've done, by all means do it again. Be careful to avoid over-manipulation of the wiring because it can momentarily reposition the loom, temporarily putting the problem into remission (only to return later). If you identify a wiring problem back there, the easiest fix would be to wire-tie the loom up and away from where it lies naturally to prevent shorting. Pulling the loom out physically to locate and patch the problem area would be better and this would weather-seal the loom, but it's not easy of course.

Check these couple of things out and let me know if you have any questions or problems.

Good luck!

Ed

Customer: replied 2 months ago.
have no engine light on and the only reason it comes on is because i forget to tighten gass cap is it plug wires or possibly plugs had them replaced at 95000 miles
Expert:  Dodgerench replied 2 months ago.

Thanks.

With no codes stored - at least relevant codes - check that wiring harness tip I sent. Shorts on the back side of the passenger side cylinder head happen often enough that it merits a try.

You don't have plug wires on this engine, but flashover can strike a 4.7 engine pretty much any time (it just gets more common with higher wear on the plugs). The rubber insulation on the plug end of the coil tends to become stiffer and less forgiving with time and heat, so the grip and insulating quality of the coil boot may have eroded. I like to use silicone dielectric grease on the inner coil boot contact surfaces for this reason.

If what you feel is consistent with a single cylinder misfire, I'd consider pulling the plugs and coils for an inspection.

Ed