I have a 2008 Grand Caravan SXT 3.8L engine with 84k. It performs good around town and on the flat highway. However, when I start up a hill (on the highway) I start loosing power. I can hear it drop out of overdrive into what I think is 3rd gear. But it still seem sluggish. It the hill is long enough or steep enough it will eventually drop down to 2nd gear. At which point I'm down to about 45mph and 4k rpm.

I know this is not right as it has always had plenty of power to make it the hill that I normally drive.

My fuel mileage has not shown any significant change; 23-26mpg on the highway.

I did get a P0420 code right after this started. Not being sure if it was related I cleared it to see if it would come back..

I did clean and test the MAP sensor thinking that was the problem. The sensor appeared to test good. The sluggishness went away but then came back.

The P0420 code came back and the van is still wimpy going up hills.

Thinking the MAP sensor was intermittent I decide to replace the MAP sensor and to address the P0420 code I replaced the DownStream O2 sensor. I reset the code and took it for a short test drive. It looked like I had fix the problem.

Yesterday the wife and I took a trip 30 mile trip to go shopping. Well the P0420 codes back and the vans sluggish again.

Can anyone point me in the right direction? I'm thinking the cat is starting to fail.

Any help would be greatly appreciated!

P.S. I have the freeze data from the P0420 code if that will help.

 

Yup, from reading a P0420 is usually a plugged cat. A competent shop can pressure check the exhaust and determine if it is plugged.

Why am I reading about 4-5 year old vans with plugged cats so often and not so much on older vans? Hmmm

http://www.obd-codes.com/p0420

 

Thanks for the reply Cougar.

Ooops! I don't know why I said the vans was a 2008; it's actually at 2006.

We bought the 7yr/70k extended warranty so that long gone.

I don't think the cat is completely plugged. But it may very well be partially plugged; thereby only causing enough back pressure to cause performance issues when under a load.

I was looking at a Bosal cat through RockAuto. Its a complete one piece unit which would make it simpler to change out since this van has the Stow-n-Go seats.

It this a good choice or would I be throwing Good Money after Bad?

Any recomendations?

 

Some states have an 8 year or 80k emission warranty. You may want to check that first unless you are over the 80k.

 

Jeese ya I forgot. I'm thinking it's a federal warranty. Might check into it if your under the 8 yr 80K marks.

 

Thanks guys for the information.

But, just as my luck goes the van has 84k miles on it even thought its only 6yr old.

So I guess its on me for any parts.

Any recommends on a good brand of cat?

I was looking at the "Bosal" and the "Eastern Catalytic" brands through Rock Auto."Bosal" has a direct fit unit while "Eastern" has a two piece unit.

I like in Arizona so I don't have to be concerned with a California certified cat.