Poor mileage loss of boost issue

[draxxus131]

Hi there folks, recently ran into a slight issue with my 2015 FiST. It seems to be eating up the fuel way too much with a slight loss in power. Usually sits around 25-26psi on avg at WOT, lately only hitting 23.75 max even with the warmer weather. A full tank of gas goes by in about 3-4 days now, I do not drive fast generally, max 20 miles. Just performed a spark plug change moments ago, gapped to .026 ruthenium 1-step colder, previously had denso iridium gapped to .028. Checked boost hoses, passenger side was severely loose, fixed that just a moment ago. My setup involves an X37 turbo, and the usual bolt-ons minus a downpipe(stock). Fiesta has 46k miles right now with a fairly fresh oil change. Lastly, I have no check engine lights and 0 codes being rendered,

Any suggestions wonderful forum creatures? I have not checked MAP or MAF sensors yet. The original O2 sensors are still installed although the X37 has been on for roughly 16k miles. I'm pulling my hair out over this right now.


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[TyphoonFiST]

Have you test drove it yet after just fixing the loose hose a moment ago? If NOT...please go test drive and report back.

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[draxxus131]

Just drove it around town, slow first then in sprints. Did about 15 miles, still seeing the same boost loss and fuel economy issue. I did notice during the spark plug change that the COP rubber boot is starting to look very worn!

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[draxxus131]

Have you test drove it yet after just fixing the loose hose a moment ago? If NOT...please go test drive and report back.

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Good to see you in the forums still

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[TyphoonFiST]

Who is your tuner?

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[TyphoonFiST]

I'd suggest doing a KAM reset also* It can be done through the AP3 if you have one*

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[draxxus131]

Tuned by tune+, currently have an AP3 as well. Would a KAM reset be necessary? I've only done 1 KAM reset since I purchased the car new.

Just remembered that the other day I was going down the freeway, and something made me want to check my fuel maps. Hit my cancel/cruise control button to check which map I was on since I had just noticed the car eating up fuel. Magically the car could not change maps oddly enough. Pulled over checked which map I had installed, although everything looked peachy I chose to reinstall the exact same map that it stated was already loaded. On-the-fly map switching came back, fuel consumption stayed. I have absolutely no idea why or how I could not switch my fuel maps on my steering wheel at that exact moment on the freeway.

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[TyphoonFiST]

I'd try it....you just changed plugs....right? Id do it so the car can relearn itself.

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[draxxus131]

Alrighto, just did the KAM reset. Will be driving in the AM and reporting back early afternoon.

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[Ricky ST]

I am interested in a reply. I would figure after plugs, and swapping tunes I would do an OG battery terminal pull to reset the basics. What exactly is a KAM reset?

 

[Se7eN]

Did you check the hoses close to the throttle, one of them has check valved that might blow for the Purge Valve. The second one is the PCV system also has a check valve. Do you have purge valve codes? Is the manifold and turbo tight?

 

[TyphoonFiST]

Forgot to ask* Do you have an OCC? IF so make sure the check valve is closed all the way....this can cause a boost leak also*

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[draxxus131]

No codes, manifold and too are tight from what I can tell. I have no OCC, none whatsoever. Going for a drive in a minute, thinking of cleaning MAP and MAF sensors right now before I go.

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[TyphoonFiST]

No codes, manifold and too are tight from what I can tell. I have no OCC, none whatsoever. Going for a drive in a minute, thinking of cleaning MAP and MAF sensors right now before I go.

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Just go drive it now before all that other stuff*

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[haste]

It could be the "winter blend" fuel. It's definitely that time of year....

 

[draxxus131]

Did a 22 mile drive, everything seems to be fine now. I'm not sure if it was the KAM reset or dirty sensors.

Thank you everyone for the input, it is very much appreciated. I love you all in a very human way.

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[TyphoonFiST]

Did a 22 mile drive, everything seems to be fine now. I'm not sure if it was the KAM reset or dirty sensors.

Thank you everyone for the input, it is very much appreciated. I love you all in a very human way.

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Good to hear!

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[EscoFist]

Did you check the hoses close to the throttle, one of them has check valved that might blow for the Purge Valve. The second one is the PCV system also has a check valve. Do you have purge valve codes? Is the manifold and turbo tight?

Where are those check valves on the pcv? I'm losing some pressure and hear a hissing around that area

 

[Se7eN]

Where are those check valves on the pcv? I'm losing some pressure and hear a hissing around that area

Front of the manifold on top of the throttle is the Purge. One to the passanger side is the PCV. They both have check valves to keep the boost from leaving. The check valves can break.

 

[draxxus131]

Update:.

Seems to still be using excess fuel despite the efforts. If I did the math correctly with my recent long distance drive, I'm achieving 300 miles to the tank which equates to roughly 24mpg, even outside of boost on the drive. An instant occurred where I could smell a slight wif of gasoline when leaving from a dead stop at an intersection, nothing out of the ordinary that sticks out in the engine bay; besides mods of course.

At barely 46k, would a slightly stuck open fuel injector be probable?

Another area to note, a friend of mine hooked up a $8k snap-on scan tool to my FiST and it showed no codes either, except one small thing, my AFR sensors (O2) were reading slightly higher by what he called "2 points". I will have to verify this tomorrow though on exactly what he was describing.

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