My 2005 SXT with the 3.3 V-6 has what seems like a "surge" issue. Under certain conditions such as driving on a level road between 40-50 MPH in top gear (4th), the engine's power delivery is unsteady. If this was a carburized car of the mid-70's, I would say it is running lean.

Symptoms started around 70,000 miles and were very mild after the first start of the day and was most noticeble when warming up. Starts easy, gas mileage is good (low 20's) and accelerates strong. Just this annoying cruise (light but steady throttle) condition.

The Caravan now has 91,000 miles. The spark plugs and wires have been changed. Plugs all looked similar. Never get a MIL light and no codes are stored. Transmission filter and fluid changed. No changes to the symtpoms which I didn't expect but performed as routine maintenance.

Thoughts, ideas and suggestions?

Sorry if this is a duplicate thread.

 

It could be an o2 sensor or the torque converter is going in and out of lock up.

 

Thanks. I'll double check the tach - but I've never seen it wiggle. I have felt the torque converter clutch shudder on the '93 Grand Caravan plus the '94 Vision ESi and '97 Vision TSi. But good point cause if I manually select drive (third gear) it immediately goes away.

Would a lazy o2 sensor provide a code or MIL? Would it be the upstream or downstream sensor?

Thanks

 

I may be really embarassed!

I finally got the van from my wife and drove it to work. I was doing a routine under hood check (fluid levels, etc.) I figured I'd double check the vacuum hoses and plug wires. When I pushed to seat the front center coil wire, it moved and "snapped" into place.

Either it had come loose or (more likely!) I didn't completely seat the spark plug wire on the coil terminal when I replaced the wire set. Duh!

The drive home tonight may confirm the surge was due to my own shotty workmanship! :-)