Mileage drop after new injectors

[Richard05]

So My 05 3500 has just over 300k on it and was in dire need of injectors. Bought 6 new Bosch injectors, connector tubes, hp pump, FCA,from a very reputable company. Did a valve adjustment on the way out.
My fuel mileage dropped from 19.4 to 13.8.
Anyone else ever run across something like this??
Truck runs great, no miss or smoke. No more rough idle, no more rpm hang on the highway.
No codes, no check engine light.

 

[AH64ID]

Is that had calc or off the overhead?

 

[Richard05]

Is that had calc or off the overhead?

That is off the overhead. I've never really hand calculated it ever. Also I know it's not from summer to winter fuel because I buy it 500 gals at a time and am still on the same load of fuel as before.

 

[AH64ID]

It’s very hard to judge actual mileage difference off the overhead. The truck doesn’t measure fuel burned it’s just going off the amount it thinks it’s burning.

Old worn out injectors can let more fuel thru than the computer thinks so it gives a falsely high mileage.

I would hand calc a tank or two and see where it’s at. If you have any old records you can compare them.

 

[sag2]

When we put injectors in the neighbors 2006 the overhead changed fairly dramatically. It was the overhead, not the actual mileage that changed.

 

[AR Treefarmer]

Did you put reman or new injectors in? And where did you buy them from?
I'm at a point where I need to do mine, but having trouble finding new injectors that are not $$$$.

 

[Richard05]

I bought brand new bosch 505 injectors from injectors direct. I bought new connector tubes and a reman hp pump at the same time.
I think it was about 3900 all said and done.
then i did the upper valve cover gasket and an oil change too so add another 100
4k all done

 

[chunter]

I put new Bosch injectors in my truck back in October 2020 and my mileage dropped from the low 19's to the 14's (calculated not using the overhead console)
I moved to Northern Idaho about the same time, so I have been attributing my lower MPG due to the colder climate.
It will be interesting to follow your post and see what you determine to be the cause.

 

[cerberusiam]

I bought brand new bosch 505 injectors from injectors direct.

505's are not new injectors, those are remans. For the 04.5-07 the 238's are new latest revision injectors.

 

[Regcabguy]

Mads told me they can supply some new ones straight from Austria.
Anybody in California can get any of their higher hp injectors sent to their California residence directly and not going through a friend out of state. Too many rules here.

 

[NIsaacs]

Here is a link to Injectors Direct, they appear to sell brand new Bosch injectors for the '04.5-07 5.9.

https://r.search.yahoo.com/cbclk2/d...DMgRydAMw?IG=0afd0edfb1da4343a7000000001f9276

 

[Darkbloodmon]

Is your ECM flashed to the latest DRB III updates? My 03 was so far behind on updates the new injectors and FCA weren't recognized when installed and displayed the same idle hang symptoms as the set and parts that came out. When I did my research on these forums there was mention of a service bulletin for a flash update on hanging idles. Flash solved my issues post install of new parts.

I agree on keeping a mileage log though, I have a captains log for every key on key off trip/ repair/ modification/maintenance item, etc. Just for diagnosing things. It really helps you back track and isolate issues and trends.