Bad mpg and boost control valve problem

[Jasonz28camaro]

jasonz28camaro
jasonz28camaro
New Member
Wondering why my wife's 2014 sport gets bad fuel mileage. She drives 80% highway and only gets 14.5mpg. We took it on a trip once and got 17 somehow highway only.

Recently I purchased a CAI for the car and I just drove it for the first time and noticed a strange sound like the BOVs opening under boost right away. With the stock intake I could not hear this noise but the car is no faster or slower with the CAI so I'm assuming the noise has always been happening. I ran the car with my phone app and OBD2 to monitor MAP levels and it spiked and fell off fast (up to 180kpi then around 100kpi) . Turns out under the engine cover (I have never removed it) there was a vacuum / boost hose disconnected from the pressure side piping to the Pierburg boost controller valve PA6-GF30. The valves were in fact bleeding down the pressure right away and might have been doing this since day one.

I fixed the problem, no more noise and it holds around 10-12psi (170-185kpi). The car now drives good and has a good amount of power now, still not a racecar but better for sure. Attachment photo shows hose that was disconnected. It's the one with the new clamp installed all bright and shiney.

Now my question, would this be the cause for crummy fuel mileage? I'm assuming ecoboost means better fuel economy and I didn't use the turbos hardly with the disconnected hose but at the same time more air means more fuel.

 

[Gjkrisa]

I guess for having so much power it's Ecoboost I get 16mpg with my sho I would get 19 in city  with my 95 tbird 4.6v8 but that was a lot slower.

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The tbird could idle for 5 hours and use a quarter tank the sho idles for an hour and uses close to a quarter tank so I started driving my Subaru for small trips where I high idled it for 8 hrs  at 2500rpm used an 8th of the tank

 

[Jasonz28camaro]

It's sad because my 2007.5 Duramax gets better mileage, 21 highway and 17 combined.

 

[SHOdded]

That hose has been known to come loose frequently of its own volition, good you found it and clamped it down.  Haven't heard anyone complain of bad mpg with it though, but your XSport may have been driven longer with this hose popped.  Turbo piping tends to come loose or split at the clamp, etc.

http://www.ecoboostperformanceforum.com/index.php/topic,4872

How has the mpg been since you secured the hose?  Have you pulled codes from the PCM?

And, welcome to the community, please do make an intro thread for yourself here:
http://www.ecoboostperformanceforum.com/index.php/board,14.0.html

 

[MiWiAu]

I've never averaged anywhere near the EPA highway rating of 22 MPG on my XSport since I got it in August.

If I stay out of boost (rarely), I average about 17.5 MPG combined. Usually I'm closer to 16.5-17 MPG. My last road trip (80% highway, 1000 mi) I averaged about 19.5 MPG.

I got similar mileage on my 01 F150 Supercrew (4.6L V8) that the XSport replaced, but I have gobs more power now. A little disappointed, though, since I thought I'd get a minor improvement in economy vs the truck it replaced.

Seems at 60-65MPH on flat ground with no head wind, my fuel economy gauge hovers around the 22-23mpg mark. Which is probably where they ran it on their treadmill for EPA ratings. LOL As soon as I hit a slight increase in grade, the meter drops below 20 MPG.


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[derfdog15]

I get a whopping 13-16 mpg in the city currently (but I am on E20 so my MPG is skewed a bit).

As far as that hose, it is the TIP sensor reference, so I could see it affecting MPG as the throttle may have been fluttering under certain conditions causing MPG issues.

I would do a trip reset of MPG and monitor that vs. your all time, to see if it has improved.

Highway I got close to 25mpg on my SHO when I was stock, now I get around 21mpg.

 

[Jasonz28camaro]

That hose has been known to come loose frequently of its own volition, good you found it and clamped it down.  Haven't heard anyone complain of bad mpg with it though, but your XSport may have been driven longer with this hose popped.  Turbo piping tends to come loose or split at the clamp, etc.

http://www.ecoboostperformanceforum.com/index.php/topic,4872

How has the mpg been since you secured the hose?  Have you pulled codes from the PCM?

And, welcome to the community, please do make an intro thread for yourself here:
http://www.ecoboostperformanceforum.com/index.php/board,14.0.html

My wife just drove 35 miles with a great trip started and got 17mpg. Roughly 60-70% highway. Not sure if it's an improvement but I'll check it when she gets home tonight to see if it dropped more.

 

[Jasonz28camaro]

I get a whopping 13-16 mpg in the city currently (but I am on E20 so my MPG is skewed a bit).

As far as that hose, it is the TIP sensor reference, so I could see it affecting MPG as the throttle may have been fluttering under certain conditions causing MPG issues.

I would do a trip reset of MPG and monitor that vs. your all time, to see if it has improved.

Highway I got close to 25mpg on my SHO when I was stock, now I get around 21mpg.

Funny that you say TIP because while I had the engine cover off I noticed the throttle blade cover was missing. It's a black o-ringed circular cover on the side of the TB. Not sure how it came off because I can't even get it back on all the way, I'll need to mess with it more. I'm assuming it's just a dust cover but if it's something more someone please let me know.

 

[camthman]

Missing screw on MAP sensor?

 

[ZSHO]

I get a whopping 13-16 mpg in the city currently (but I am on E20 so my MPG is skewed a bit).

As far as that hose, it is the TIP sensor reference, so I could see it affecting MPG as the throttle may have been fluttering under certain conditions causing MPG issues.

I would do a trip reset of MPG and monitor that vs. your all time, to see if it has improved.

Highway I got close to 25mpg on my SHO when I was stock, now I get around 21mpg.

Funny that you say TIP because while I had the engine cover off I noticed the throttle blade cover was missing. It's a black o-ringed circular cover on the side of the TB. Not sure how it came off because I can't even get it back on all the way, I'll need to mess with it more. I'm assuming it's just a dust cover but if it's something more someone please let me know.

Its only a dust cover,you can try to put a tiny tab of crazy glue along the inner edges for good measure but would not worry about it. Z

 

[Jasonz28camaro]

Missing screw on MAP sensor?

Nope. Saw that too lol. From factory it's not tapped for a screw so it's not missing I guess. The majority of carts I have came across only have one screw area where most all MAP sensors have provisions for two screws.

 

[metroplex]

I put a clamp on that hose, but honestly it was very difficult to pull off that hose even without the clamp. The oil is from the turbocharger seals allowing some oil to escape. My rear charge pipe hose connection is always seeping out oil residue, even after I swapped clamps. It's leaking from the connection so it's not a hose or pipe failure, rather inadequate sealing. I'm going to swap out that section of hose for a silicone reducer coupler and use constant-torque liner clamps - all of which is not cheap (roughly $60 worth of parts). I've seen others with similar leaks at other parts of the charge piping.