Dpf cleaned and mileage dropped 1 mpg

[Rawze]

Sometimes replacing sensors with new ones that are updated part numbers require a software update too. This is especially true of emissions system components. Running the latest version of software in your ECM?.


It could also be that the old sensor was allowing the Emissions system to be too lenient, raising fuel mileage? and now it is working normally?.

For all anyone knows the CAC could have cracked, or EGr valve started sticking, or some other unrelated problem or sensor reading wrong out of sheer coincidence.

I know one guy who had his clutch replaced and lost 2+ mpg. 5 different shops could not find anything wrong with it. the guy was convinced there was something wrong with the clutch install or that it was slipping sometimes, or some other thing. -- He came over here and while his truck was idling, I just happened to see fuel dripping from a leaky fuel line down onto his exhaust then evaporating away. It was a wonder his truck did not burn to the ground.

Like I said,.. it is any ones guess.

Has your boost and pyro readings changed?. a sudden 1 mpg change in efficiency would show up on those gauges unless perhaps you had a fuel leak somewhere.

You said the DPF was cleaned, anyone inspect the SCR face?. Did anyone inspect the decomp tube? Did anyone clean the DOC? - Were they flow tested before the re-install?

did they do other service to the truck? replace fuel filters? or other things?

[snailexpress]

I would start from simple things. Are all exhaust gaskets installed new and properly? DPF gaskets? Leaking exhaust will screw up everything.

[bossboy2]

(05-08-2018 )Trucker750 Wrote:  

(05-08-2018 )Rawze Wrote:  There are a lot of causes for fuel mileage dropping. Simply cleaning the DPF properly is not one of them. Something else caused it. Perhaps they worked on something else or replaced a sensor with a defective one?. Maybe a leaky doser injector?

Is it possible that a clogged intake system could account for the instant drop of 1 mpg just because the dpf was cleaned? Maybe the egr valve is so clogged it can't open normally, and the change is exhaust backpressure is now requiring more or less flow that the clogs will allow, equaling lost mpg? All without throwing codes? I'm a mechanic as well as a driver, but the computer systems nowadays are new to me.

Yes, it is possible. Earlier this month a forum member here asked about my oil sample and why the soot level was so low. That got me thinking perhaps it was clogged somewhere and no exhaust gas was coming thru the EGR system. I opened it up and found the venturi port clogged so tight it took a pic to get it open. I cleaned up the delta-p and the IMAP sensor. I didn't see any difference in mileage. About two weeks later I replaced them both due to a recommendation by someone on this forum. Last week I had the best fuel mileage ever. 9.1mpg. Prior to that I was at 8.2 mpg. Take it apart and change the sensors.