2006 175K miles. I seem to be using more fuel that usual.

New o2 sensor in 2015
New Plugs/Wires top quality NGK
No CEL
K&N Air Filter
Mobil 1 oil since new.
New tires, balanced, over inflated a few lbs.

All fluids, belts tensioners new greased etc...

How long do the catalytic converters last? Getting clogged maybe?

Appreciate any ideas.

 

Coolant temp sensor maybe sending info to the ECU of your engine being still cold or heating up when its up to heat. So more fuel would be added. Worth a try.

 

I just filled it up tonight. 340 miles in 19.4 gallons.

Plugs are clean
O2 sensor new oem 3/2015
Brakes new not dragging
New tires
Just aligned

New water pump, radiator. Coling system cleaned and flushed.

I just filled the tank with 92 octane. See what I get. I'll check the temp sensor but the gauge is correct.

 

Not sure but think there is two temp sensors.
Checked and there's only one coolant sensor. 2004 part no is 5269 870AB

 

I only see the one for the coolant but I can check the book.

 

There's an ambient air temperature sensor that could be off. If you have a readout in the car for exterior temperature, check the readout. It uses the same source, so if it's off, get it fixed. If it's correct, then you can rule that out.

 

Yes, that is correct. I checked it and it is correct.

 

If everything on the ignition side is good then the next thing I'd be looking for is vacuum leaks.

Now the 3.3 and 3.8 V6's have an issues with the intake valley gasket breaking down over time and this can result in a drop in economy. On mine it was a fairly quick process. within about a week or two. However, before I ripped it apart I'd do a vacuum check. with good compression it should pull between 17 and 19 inched. If its below this then I'd be looking for leaks.

Another thing thats worth doing if it is a leak is the vacuum pipes.

I've had to do this twice. On my own and on my girlfriends 2006 3.8.

depending on where you are, prices for gasket sets can vary. Felpro have a good set with everything in there for around $25 from Autozone. I purchased a set of replacement vacuum pipes on ebay for around $15.

Honestly if I ever buy another one of these vans. If its running more than 100,000 miles I'll just do it anyway.

 

I checkfor vacuum leaks all of the time. I took a few recordings and we are getting about 17.4 mpg combination highway/local but did notice my wife cruisin at 90 so there is my answer.

She complained last week.... said she got in and couldn't even hear the engine running.

I just flushed the power steering fluid, added a filter, cleaned the resivoir and relocated the p/s cooler. Atf +4 Synthetic.

The engine is running flawlessly, perfect idle, pickup etc...

Maybe just a little old age?

Injectors are original so is the cat, figured maybe a cat getting clogged or dirty injectors?


BTW: Unlike my VW. MPG stays the same with 87 89 and 92 octane fuel.

 

Hahah yeah that will do it. Although these vans are surprisingly stable at high speed so I can understand. LOL! I've had mine on the German Autobahns a few times and they'll pull way past what Chrysler say they'll do. Though fuel and economy no longer fit in the same sentence at that point!