Hi Gang, We are on the road with our '09 E350 V10 pulling our travel trailer. Coming out of Illinois we were getting our normal 8mpg pulling the 8,800lb trailer, but after a couple days in Springfeild MO. we are getting 5mpg. as we have driven from there to central NM. Around 5 tanks of gas with no change.

I did run a tank of 93 octane through it to see if it helped.

The van has 21,000 miles on it and it is bone stock except for a K&N filter that I put on 5,000 miles ago. I plan to wash the K&N in the morning put it doesn't look very bad yet.

Even driving it around without the trailer is showing poor mileage - no full tank tests but the in-dash says 10mpg without the trailer. Previously I got 12-14mpg with it in town.

Could the K&N casued a problem? Or could it have been some bad gas? Or is it a computer thing - no codes?

Open to about anythingThanks,
Larry

 

most people here are firm beleivers in using the stock motorcraft air filter over anything K@N sells..

have you tried replacing the air filter/housing back to stock for a tank of gas ?

p.s. for that matter make sure the air filter/box assembly is properly attached/sealed up.

 

Does Illinois have real gas and MO. have E10?

 

Illinois is corn country - by law everything is E10.

Would that cause me to get better mileage there?

 

I was also wondering if altitude could be the problem. We were 500 feet above sea level back home and have been climbing since we left - now at 4500' above SL.

If so how do I do a reset to the system?

 

E10 would get less mpg compared to regular gas. Not sure on your altitude question.

 

Higher altitude will lead to less power your engine can produce.

 

My F-350 V10 has way more miles than yours but I had the same thing happen last year towing my trailer. Mine ended up being a manifold leak which caused the EFI to pump more fuel to compensate. I was down to 4 miles per gallon when this happened. A quick diagnostic check at a reputable mechanic will probably be able to tell you right away.

Vince

 

Thanks Vince and everybody else.

We made the pull up to Santa Fe yesterday after cleaning the K/N and MAF but it was no test because I was fighting a 35+MPH headwind 2/3rds of the way and a side wind the rest. Got 5mph with the wind and making the climb to 7,200ft ASL. On monday we are heading down to Albq. so that should see if my cleanings made a difference.

 

Welcome to NM, hope you enjoy your time here plenty to do and see here. The wind seems to blow this time of the year, be careful the gust through some of the canyons and out on the plains can really move you around when towing. We are still running the winter blend fuel around here which can hurt MPGS by a couple miles per gallon too. But I have not seen numbers that low towing with my F350.

 

I think you are on the right track with the altitude being at least part of the issue. Less air density = less engine power = more right foot on the throttle to maintain highway speed.

BTW, I have K&N air filters in every rig I own and have always seen a 1-2 MPG increase. I know some people hate them and say they don't filter well, but my experience shows otherwise.

 

As far as gas mileage, winter blend and E10 have contrived to lose me about 1-2 mpg in NY State to about 10.4/6 regular driving to about 12.4 open road. When I travel South of here, i.e. PA, regardless of the time of year, I will always pick up most of that mileage per gallon again - to 14 or better open road. When I'm pulling my 11,000 5th wheel camper - it's even more evident. The wife's V6 Escape will also pick up 1-2 mpg going South(and it's not because I'm going downhill).