2004 3.8l Dodge Grand Caravan with all sorts of quirks. Driving me mad!

ERIC1417

MEMBER
2004 DODGE CARAVAN
6 CYL
FWD
AUTOMATIC
116,000 MILES

We just got an 04 Grand Caravan w/ 116K on it this past month. The CEL came on about 100 miles after we bought it. It reads code P031 Cylinder 1 Misfire. Replaced plugs, wires and coil pack and had the PCM flashed. I also had compression checked and that was fine. Light still is on. Essentially, it runs really rough when idling. If I rev the engine slightly the miss goes away. When driving at highway speeds you can not feel any type of miss. Also, Im not sure if this is related but everytime I fill the gas tank up and drive maybe 500 feet the van will***** harshly then drive fine. It has even stahled a few times directly after filling tank and idling. We haven't gotten the title back from the state for this van, but we are seriously considering selling it already. I want to fix it but noone can tell us what is wrong! Any suggestions would be GREATLY appreciated! These are just the first two of it's quirks that we need to get fixed. Thank you!

Saturday, March 12th, 2011 AT 1:16 AM

3 Replies

CARADIODOC

MECHANIC
34,330 POSTS

Chrysler has extremely little trouble with injectors but you might consider swapping two of them to see if the misfire switches to a different cylinder. Some other things to consider include someone might have replaced the crankshaft position sensor and didn't use the required spacer to properly set the air gap. That can cause a dropout in the signal at low engine speeds. Thinned out or low oil could allow a hydraulic lash adjuster to bleed down at low speeds. They take the place of hydraulic lifters. That would make a valve not open completely. While that isn't common, you would likely hear it ticking loudly.

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Saturday, March 12th, 2011 AT 1:52 AM

ERIC1417

MEMBER
2 POSTS

Thanks for reply. I swappted #1 and #3 injectors and miss still present in cyl 1. Leaked down cylinder only showed 12% leak down. Vacume reading is pretty normal as well. Wondering if I should check running compression.

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Saturday, March 12th, 2011 AT 1:43 PM

RIVERMIKERAT

MECHANIC
6,110 POSTS

Spray all vacuum lines and fittings with carburetor cleaner with the engine running. Listen and feel for the idle to smooth out or get rougher. Also, spray around the intake manifold to cylinder head mating surfaces and the whole intake manifold. This will check for vacuum leaks. Disconnect the manifold absolute pressure sensor on the intake manifold to see if that clears anything up.

Try changing up where you get gas, this will eliminate the quality of the gas as the culprit. Run a bottle of injector cleaner through the fuel system to see if that clears up the problem, though I doubt it will.
You may also have a fuel tank that has contaminants in it that are being picked up by the fuel pickup immediately following a fill up. Lower the tank, remove the pump/pickup assembly and see if the filter screen has pieces of rust or metal in it. Filter the fuel into a clean gas can and clean the tank out if so.

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Tuesday, June 7th, 2011 AT 7:44 PM