Hi, I have a 2001 grand caravan sport. 3.3 liter engine. It started running rough a few weeks ago and is getting worse. I know I need to take it in to the shop but I wanted to get opinions on the problem before I do that. It is probably just in need of a tune up, whatever that entails, timing and plugs? When you first start it up it runs rough and is "missing". And occasionally misses when driving on the freeway. If I turn on the AC the missing gets much worse, not just hesitation but obvious missing. Should I just ask for new plugs? What about timing? Could it be something else? I have 105K on it and it has been probably since 60K that the plugs were changed. I'm not sure.
Also, I assume I should get platinum plugs?
thanks!

 

If platinum plugs are in it they aren't due for a change till the 100K mile mark. That said, they could still be the culprit and are a comparatively cheap option. Sounds like it's ignition system related meaning plugs, plug wires or coil pack but could be caused by any number of things. Best to have them scan it looking at real-time data to determine what it wrong.

Timing is not adjustable on your engine. The PCM (engine computer) determines timing based on sensor inputs. Yes, use Champion or AutoLite platinum plugs. Avoid Bosch. Anymore, a "tuneup" is really just changing the spark plugs, maybe the plug wires, maybe the PCV valve and the air filter. Not like the old days when everything was changed and adjusted.

If you are seeing the check engine light a fail code is stored in the PCM. You can cycle the key to read the code but it's best to read it with a scanner - free at most parts stores. The code will lead you to the culprit.

 

At 150k, you're surely due for the front O2 sensor if it hasn't been done. Avoid Bosch as mentioned on the plugs.