I could have sworn I hit the 'post button'...

Where'd it go george?

Anyhow, I'll try posting this again.

I'm getting terrible fuel mileage on my new-to-me 2006 CTD Mega cab. Empty it isn't bad at all.. 20mpg according to the overhead computer... when I stay near the speed limit of course. What I'm not impressed with however is the mileage towing!

I have a 19ft Travel Trailer and I just finished a 1000km round trip. I averaged about 9.6-10mpg hand calculated. The overhead computer agreed.

I spoke with the local shop and he suggested that at 80,000kms that my Cat may be plugged, or getting close. He suggested a 4" exhaust, removing the cat. He said I should see my mileage return to acceptable plus 1-2mpg. I already have a CAI so it makes sense to me.... I'm not crazy about chipping the truck as I just dropped $3500 on a 'service plan' from Dodge when I bought the truck. At least the exhaust only voids the warranty on the exhaust..

Am I barking up the right tree with this issue? The truck just came out of the shop from their 10,000,000 point inspection.. I'm assuming a failed injector would have come up if that's what it was.. no?

Any other ideas would be greatly appreciated. We are going on a 3700km tour in 2 weeks and I don't want to be blowing through fuel like I did with my Hemi!!!

 

Your truck already has a 4" exhaust from the factory.

If it hasn't been tuned, I guarantee the cat is not plugged on it. The cat's on them aren't much of a restriction at all. Even when the cat's do get partially plugged, one good stomp on the skinny pedal blows it right out. Normally you hear a POP and then a large puff of smoke.

If it still has the stock exhaust, the best thing to remove / replaced is the stock muffler. The rest of the system is fine.

It's not really going to net you a big mileage increase, but it will help a bit with the EGT's.

The best way to improve mileage on a diesel is with a tuner. The big money maker is advancing the timing.

There are two things on the common rails that kill the mileage and the exhaust temps.

1 - the electronic timing and 2 - the cam timing.

Both are set to reduce emissions, not make good power and economy.

Adjust the timing, swap in a new cam and that's as good as it'll get.

 

Alrighty...

#1 Thanks Coaltrain for the help on realizing my truck already has a 4" exhaust... next time, I'll go look at my truck before someone sells me some pixie dust.

#2 The truck must have had some f...ed up programming in it. I had Dodge reflash the PCM, and the Transmission as it was shifting REALLY hard and searching from 1st to 2nd.

The truck drives way nicer now. No more jerking through the gears.

Empty mileage dropped a touch.. 18.5-19mpg (Computer) with 3 adults in the truck on a 2 hour round trip. I used to see 20mpg on the same trip... could be driving style however.

I haven't towed the trailer since re-flashing it.

Now that I know the 'starting point', we'll be able to make smarter decisions moving forward.

 

stock exhaust is 4 inch like coal train said
i had a magnaflow and a MBRP and i like the MBRP a little better 4" turbo back with a 5 inch stainless tip. It gives that low diesel romp! I love it

 

I would go with a cold air intake, programmer, and either a 5in exhaust or delete the muffler. With just a cold air intake and 5 in exhaust on my uncle's 2006 2500 2wd we are getting 21 around town and 19 on the highway pulling a 3000lb trailer with a 5600lb car on it.

 

5" exhaust does nothing on a truck with a stock turbo expect increase the volume of air that needs to be moved.

Unless you are over the 550 HP mark and are using a turbo bigger than a 64, you'll see no benefit in a 5" exhaust.