Diesel Question

[Phillip Franklin]

As I'm sure everyone knows that when a vehicle is built, the manufacturer loads a standard program and tune into the ECM. On gas engines, the ecm has the ability to do fuel trim to adjust the fueling to meet the target map requirements. It uses the O2 sensors (amongst other sensors) to calculate required injector time to get the Fuel/Air ration. That is why when you get a new vehicle you don't get the best fuel efficiency until around 8000 miles.

So, I have been told by other diesel owners that it takes around 16K-30K on a diesel before you know how fuel efficient it will be. Does anyone know why this happens......far as I know there isn't an O2 sensor on the diesels.

 

[Travelin Ram]

What you’ve been told is wishful thinking. Mostly offered with the belief that a diesel takes tens of thousands of miles to break in.

Used oil analysis tells the truth.

Gasoline needs a narrow range of air/fuel to burn cleanly and make power. Diesel does not.

Also FWIW the short and long term fuel trims on a gasoline injected engine adjust a lot faster than 8k miles. I say this based on experience using HPTuners and other tuning tools to observe that activity when tuning vehicles.

 

[RedneckHippy]

Maybe it takes 16k- 30k miles to stop smashing the go fast peddle everywhere you go.

 

[MADDOG]

I'd say it doesn't happen. Those other diesel owners are smokin' something.

The Hwy & Combined mileage on my truck hasn't changed since the truck turned over 3k miles. The first road trip, at about 1500 miles on the odo and almost 1500 miles long, evidenced a change for the better.

Now at 27K miles I'm getting the same mileage as I did when the truck was almost new.

 

[WY-Dave]

Im @27k and same 16.5-17 (gauge) that it always has been on my daily drives.

 

[leeroy300]

with all the pollution control crap on vehicles all l ever notice is no change or lower mileage as they age and l have owned new vehicles since 1994 every 2-3 yrs cars, trucks v6-v8 gassers and now 2 diesels all but 2 were like this the only exception was my 2000 Nissan frontier went from 17.5 mpg to 22 and my 1996 sonoma with an almost identical jump as the Frontier