Engine (2005 - 3.8 ) began running very rough after a transmission downshift while going up a hill. This is the first time this has happened. Engine codes show misfire on cylinders 3 and 6 (P0303 and P0306) along with a general engine misfire (P0300). I find it odd it started with a downshift. Since the engine began running rough I have replaced the sparkplugs (which al were worn down but looked fine- light tan with no deposits). Engine still runs rough as before. I did find a comment on this site that the coil pack for this engine has 3 coil modules. 3 and 6 are on the same module. I will test the coil pack tomorrow. Any links to coil pack testing are appreciated. Any guesses why this would start after a downshift?
shadow1
No guesses here, but I DO believe in FATE. 
DO inspect the spark plug wires, some owners have reported arcing. (The old water spray test in a dark garage is worthwhile, but good luck seeing the rear ones without first removing the cowl).
Coils have often been known to fail.
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easyautodiagnostics.com
DO inspect the spark plug wires, some owners have reported arcing. (The old water spray test in a dark garage is worthwhile, but good luck seeing the rear ones without first removing the cowl).
Coils have often been known to fail.
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How To Test The Coil Pack (1990-1998 Chrysler 3.3L, 3.8L)
Chrysler 3.3L, 3.8L Index of Articles
I had a similar problem. Lifted the hood and ran the engine at idle. In the dark [night time no lights] I could see a spark jumping to ground or one wire to the other at/near the coil pack. Wrapped the offending wires in electrical tape and the problem was solved. Ran like this for a couple of years.
Update: I removed the coil pack and tested the primary and secondary circuits for resistance. All were within specs. I inspected all sparkplug wires for cuts or cracks and tested for resistance. Wires looked and tested within specs. I reinstalled the coil pack but still ran rough. I started the engine and removed each plug wire at the coil. Cylinder 3 had no spark. I should have checked that first. I've ordered a new coil pack. I did notice there is only 4.5 volts at the connector for the coil pack with the ignition key in the "ON" position. Every article on coil pack testing I looked at talked about 12 volts at the connection, with one article saying that is "during cranking and running".
original on mine, seems to be a relative rare failure IMO, doesn't seem to fail any more than other things that cause similar problems
In the past 14 years I've had four 3rd gen vans, all with the 3.3 v6 and the coil pack we are discussing. Zero problems with the coil pack and I've never replace any of the spark plugs. When I scrapped the last van I kept a few parts included the coil pack just in case. I find these engines very reliable.
Never had a coil pack failure on mine, or any personal friends' vans. That's over 20 years experience with these vans. My two high mileage vans (2000 3.8 and 2001 3.8 parts van) still likely had the original coil packs in them, both with 225,000 miles on them. My 2004 3.8 has 204,000 on it, no pack failure as well.
Heat kills electronic things (and batteries too), so I would imagine more failures in the south. Where I am we might see 90-100* days 2 weeks out of the year. An interesting sidenote: in 2001 these vans came with a molded plastic battery heat shield between engine and battery, so Chrysler was addressing an underhood heat problem.
Heat kills electronic things (and batteries too), so I would imagine more failures in the south. Where I am we might see 90-100* days 2 weeks out of the year. An interesting sidenote: in 2001 these vans came with a molded plastic battery heat shield between engine and battery, so Chrysler was addressing an underhood heat problem.
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