I have an '06, 6L F250 Lariat Crew with 16K miles. Idling about after a fill up I have hit up to 24mpg. That was cruising at idle for fifty miles or so, just letting the idle pull me out from a stop sign or signal light. And in this small burg, there are not too many of either.

Daily, hitting the Interstate at 70mph (cruise control), I average 18mpg. City driving, it drops to 16mpg. However, my wife, a conservative driver and one who has always been light on the throttle, sometimes has her city driving drop to 14mpg.

In the last 1K miles, I noticed a rough idle. It became so rough that the door panels would audibly vibrate.

Today, while I slaved away in the office, my wife took my truck to the dealership for an oil/filter change. Informed of the rough idle, they checked the computer codes. The result was identification of a 'carbonized' EGR valve.

The Service Advisor called me at that point and said they would need to remove the turbo in order to insure that it was not affected by carbon, also.

After several hours, my wife returned home with my truck, but when she shut it off, there was a distinctive, clattering/whirring noise coming from under the hood that lasted for a full 30 seconds.

I waited five minutes, then started the truck up and shut it down. The whirring/clattering noise returned. I called the dealership service advisor and he informed me that the noise was a result of PGM programing changes he made due to a Ford service bulletin. According to him, the noise was due to a forced continuation of injector activity in order to 'clean the oil' off of them to prevent carbon deposits.

Ok, is this legit or pure BS? Is my dealer just trying to silence my concern or is this to be expected?

 

Sounds like the reflash (#?) for better cold injector performance. It cycles the oil out of the injectors to prevent 'stiction' upon cold startup. Rough running cold engines were the reason for the 'fix'.

 

It sounds kind of odd, but it is a very effective fix for the cold start issues.

 

Also, to prevent the original problem you encountered, you may want to consider running it a little harder occassionally. Get it good and hot, forget about mpg, and let it clean out.

Mark

 

Cruising at idle for 50 miles or so.....man. I couldn't do that if I had to!!
dp

 

Well, it was a series of quiet country lanes. Sometimes it is nice to just count the deer instead of having to dodge them.

 

Point taken. I'll do just that.

 

Thanks for all the replies. The PGM change has produced a much smoother, and apparently quieter engine. I almost wonder if the EGR carbon was there from the beginning.

My wife ran an errand for me this morning, so she decided to fill up. She reset the computer MPG to see how the truck did today. After about 40 miles, she reported a significant increase in mileage. Mixed highway/city driving, she phoned and told me that the mileage had been hovering around 21mpg. We've checked the computer's mileage calculation and found it to be within 5% most of the time. So I'm pleased that the dealership found and remedied the problem.

 

awesome! glad to hear something positive for a change!