2000 Dodge Grand Caravan 3.8 L Sport

Tiny
FARMBOYSURFER
  • MEMBER
  • 2000 DODGE CARAVAN
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 187,000 MILES
I just replaced my egr valve which did improve my idle rpm to a bit higher. I am still getting original symptoms of bucking motion while driving, and at times what seems to be some sort of combustion bang or back fire from underneath the engine while accelerating. What is my next course of action. The van runs great and smooth until engine temp is at normal temp. Then the symptoms appear.
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Monday, August 15th, 2011 AT 3:04 AM

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Tiny
CARADIODOC
  • EXPERT
There was a problem in the early '90s that matches your description except it occurred more under load or when accelerating. That was caused by the original set of spark plug wires. It only pertained to the 3.3L engine, but the 3.8L is basically the same thing.

A cracked core in the crankshaft position sensor can cause that too but it isn't real common.
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Monday, August 15th, 2011 AT 4:59 AM
Tiny
FARMBOYSURFER
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Thanks for such a quick response. I'm not quite sure what next to trouble shoot. The Van did have a tune up with new plugs and wires at 140,000 KM. The Van now has 187,000 KM. R u suggestiing to check the crank shaft position sensor? I did take the Van to a mechanic and he had the Van idling for 30 min while hooked up to computer. No codes tripped by PCM. Fuel Pressure was 50 PSI or something. Engine Temp was running around 194 degrees. Van has never overheated. I notice on cooler days the problem is not so frequent. HELP!
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Monday, August 15th, 2011 AT 3:17 PM
Tiny
CARADIODOC
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Intermittent problems are always frustrating and hard to find. I hate just throwing parts at a problem because that costs money and introduces new variables into the mix, but you might try a new crankshaft position sensor. They often fail when they get warm, but their air gap is critical too.

New sensors from the dealer will have a thick paper spacer stuck to the end to set that air gap. Many aftermarket sensors have a thin plastic rib molded to the end. It partially wears away during engine operation so to remove and reinstall those, you are to cut off the remaining part of the rib and use a paper spacer from the dealer.

When replacing transmissions at the dealership, I got "smart" and figured I'd save people a few cents by not using that spacer. I just shoved the sensor in as far as it would go, then pulled it back about 1/16th of an inch so it wouldn't hit the flex plate and be broken. Worked fine for the first dozen, but for the thirteenth one, I heard their engine stalled intermittently starting two weeks later and another shop replaced the crank sensor. I suppose it could have been coincidence that the sensor failed, but I suspect it was my fault for not using that spacer. The point is, the problem didn't show up right away.

I'd feel a lot better if there was a fault code stored indicating which sensor was the culprit. The camshaft position sensor could do that too, but they seem to cause a lot fewer problems.
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Monday, August 15th, 2011 AT 10:58 PM

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