On a 6.7. .

Which sensor has the most impact on MPG?

 

With all the sensors in the system now, it would be hard to pick just one. Maybe the MAP?

 

Yeah I heard that

On a gas job it would typically be a MAP and/or an O2. But you are right, they all intermingle.

I am trying to figure out which one has the most impact

 

The mass air flow sensor can have a big impact on how the truck runs as well.
At least I think thats the one in the air stream that has the small white scoop on it. If its not getting a straight shot of air, the truck will fall on its face.
Part of a science experiment I have been working on.
Next test is to see what a larger scoop will do...more air might mean more fuel from the ecm.

 

I have to look at the MAF and see if it's in the right direction. I have an H & S, I scrapped the scoop and put a 3" tube right out to the grill instead. With a screen of course

I had an injector line weeping on #5, so today I redid the intake side and I guess found a boost leak somewhere. So the boost is up now and I am hoping that fixes the MPG. I fell off around 6 MPG several months ago anhd have been struggling with it since. Haven't broken 20 in months.

I figured I'd explore the sensors. I think the MAP amd MAF are behind the air filter. Then there's another one that looks like a MAP in the air horn. I am assuming that is the boost sensor.

The boost reading on the Black Maxx is about 4 PSI higher than me gauge. That's allot. I noticed the boost readings are more active now, but a short cruse didn't tell me much. So until I go on Vaca Wednesday, I won't know for sure

There's allot of variables that's for sure.

 

Check all the intercooler clamps. Those can appear tight but can require some tightening.
I replaced the boost sensor and the maps on my truck when I had issues with a a 2nd hand turbo I put on the truck. It did not help. Turned out to be fried electronics on the vgt. Turbo would not spool and whenever I came to an idle, the turbo would continue to spool down like the exhaust brake was engaging...more and more and choking the engine. I had to really coax the throttle before the vgt would respond. This turbo was cleaned thoroughly prior to install.

Like you said, there are several variables.

Are you running summer washer fluid? Change out the winter air in the tires?

 

No I'm still on the winter stuff and I just put Fall air in

The truck runs really great. Doesn't seem to be doggy or anything like that. I checked the couplers yesterday. I also have my boot between the tube and the turbo wrapped. That thing is so spongy I'm afraid it might blow out, so I shoved it into another piece of Boost tubing. It actually made a difference.

Yesterday was a bad day for me to feel it with the jeans gauge and we have more rain today. It will have to tait until Wednesday when we leave

 

The bost tube couplers seem really weak on these trucks. I was checking them yesterday, might order some after markets as preventive maintance.

 

Yeah they are

You need an accordian type. Otherwise you'll have to pull the intercooler out. Been there. That's why I took a larger piece and slopped it over the outside. Prevents it from expanding too much and blowing out

 

The MAF sensor is in the filter cap horn, the other sensor is an absolute pressure sensor, but for air filter restriction. The MAP is in the intake horn IIRC. As far as the Maxx reading, its just plugged into the MAP readout from the ECM, so who knows if thats after it has messed with it or the actual reading.

 

Exactly. The parts guy at the dealership couldn't tell which was which. The parts manuals leave much to be desired for the 6.7

I wonder if it's fueling when it reads higher. That's my guess

 

Hard to tell which route they would go when programming a power level. I thought boost fooling would go the other way where the program is trying to reach a boost pressure and it only sees an arbitrary number, not the actual boost.

That would explain why guys are telling me they are seeing 40psi boost with the BlackMAxx and my Smarty maybe hits 34. I have standalone gauges. They are making the same boost, just one displays a larger number. Wonder why?

 

It's believed the engine would be fueling with more boost

Anybody happen to know the part number for the MAP sensor?