Fuse 24 (Emissions System) keeps blowing

[Turbodhi]

I've been having issues with this fuse popping. Not really doing anything demanding, just rolling off a red light. I recently installed an access port and the stage 1 91 octane map that came with it. I installed the stage 0 map and it let me limp it back home. Any idea why this might keep blowing and is there anything I can do to stop it? The first thing that comes to mind is the fueling system pulling too much current. It's going to cause an issue with future tuning if I can't even get the "stock but better" map to play nice.

 

[SteveS]

Shorted O2 sensor?

 

[Turbodhi]

Shorted O2 sensor?

The car ran like a champ for the past 2 years on an injen intake and mbrp exhaust, both from the previous owner. Plugging in this Access Port and installing the tune are the only Non Maintenance things I've done to this car. Would the O2 sensor just suddenly start shorting like that?

 

[SteveS]

Not necessarily, but fuses generally blow from too much current, and usually that means something is shorted and flowing too much current.

 

[Turbodhi]

Not necessarily, but fuses generally blow from too much current, and usually that means something is shorted and flowing too much current.

any idea on what else is protected by this fuse that I can check for shorts?

 

[Capri to ST]

This is what is in the manual for fuse 24, but it says coils not emission system.

 

[Turbodhi]

This is what is in the manual for fuse 24, but it says coils not emission system. View attachment 55796

my owners manual says emissions system so that's the one I'm going off of. I'm not next to it right now so I can't take a picture but I will when I get a chance.

 

[Capri to ST]

my owners manual says emissions system so that's the one I'm going off of. I'm not next to it right now so I can't take a picture but I will when I get a chance.

Maybe it's different for different years? I have a '16 just for reference.

 

[Turbodhi]

Maybe it's different for different years? I have a '16 just for reference.

So it seems...yeah I have a 14. Rolling back to the stage 0 map got me home. But the fuse popped again almost instantly after trying out stage one again. It really seems like something about that map is causing a lot of current draw through that circuit.

 

[M-Sport fan]

my owners manual says emissions system so that's the one I'm going off of. I'm not next to it right now so I can't take a picture but I will when I get a chance.

Technically, the ignition IS part of the emissions system.

 

[Turbodhi]

Technically, the ignition IS part of the emissions system.

Technically correct, the best kind of correct haha

 

[Turbodhi]

Update: did some more testing and the issues still shows up on the base map. So it looks like I'm still at square 1. Does anyone know what's on that circuit? I'm finding conflicting info with later model Fiestas.

 

[Turbodhi]

Another update: I did some more reading and chatted with a guy on Reddit. I decided to unplug the evap purge canister and cruise around to see if the issue popped up again. I've heard similar symptoms from that part malfunctioning. The issue is also intermittent so I'm still testing. The Injen intake is also kinda loose now and it does wiggle/bump that purge valve so I wouldn't doubt it got messed up over the years. The vehicle does also stall a little bit after refueling so I'm hopeful this is my issue.

 

[Turbodhi]

Well that didn't fix it either. I was cruising around and it popped again as I was idling at a red light

 

[scooter123]

Wild guessing here but you may want to look closely at every wiring harness in an area where it may have been disturbed by installing that intake. Basically it may have been displaced in an area where it's been rubbing thru the insulation on a critical wire. That can cause an intermittent short to ground and may drive you a bit nuts trying to track it down. So look real closely at any wiring harness that may have been pulled away to install that intake. BTW, if the rub is only thru the insulation and exposing just one wire a couple of wraps with a quality electrical tape will provide an effective repair. If more than one wire are rubbed thru or that one wire is partially cut then you will have to totally strip and repair the wiring harness. If the wiring search turns up dry them perhaps a new O2 sensor or both would be a sensible item to replace. IIRC they are rather easy to get to and heated O2 sensors carry everything needed to create a short circuit.

 

[Turbodhi]

Wild guessing here but you may want to look closely at every wiring harness in an area where it may have been disturbed by installing that intake. Basically it may have been displaced in an area where it's been rubbing thru the insulation on a critical wire. That can cause an intermittent short to ground and may drive you a bit nuts trying to track it down. So look real closely at any wiring harness that may have been pulled away to install that intake. BTW, if the rub is only thru the insulation and exposing just one wire a couple of wraps with a quality electrical tape will provide an effective repair. If more than one wire are rubbed thru or that one wire is partially cut then you will have to totally strip and repair the wiring harness. If the wiring search turns up dry them perhaps a new O2 sensor or both would be a sensible item to replace. IIRC they are rather easy to get to and heated O2 sensors carry everything needed to create a short circuit.

Awesome. I'll work on that today. Unfortunately I live in an apartment and don't have a jack so I'm going to have to get clever about reaching the O2 sensors. The vehicle only has 114k miles on it so they probably need to be replaced anyway.

 

[Turbodhi]

Wild guessing here but you may want to look closely at every wiring harness in an area where it may have been disturbed by installing that intake. Basically it may have been displaced in an area where it's been rubbing thru the insulation on a critical wire. That can cause an intermittent short to ground and may drive you a bit nuts trying to track it down. So look real closely at any wiring harness that may have been pulled away to install that intake. BTW, if the rub is only thru the insulation and exposing just one wire a couple of wraps with a quality electrical tape will provide an effective repair. If more than one wire are rubbed thru or that one wire is partially cut then you will have to totally strip and repair the wiring harness. If the wiring search turns up dry them perhaps a new O2 sensor or both would be a sensible item to replace. IIRC they are rather easy to get to and heated O2 sensors carry everything needed to create a short circuit.

Well I did some rooting around in the bay and found 2 wires that have been rubbing up against a line that comes from the coolant reservoir. I'm still learning about Fiestas so I don't know what this is but I'm going to slap some tape on it and see if it helps.

 

[Nitelife]

Coolant bypass solenoid??

 

[Turbodhi]

View attachment 55824
Coolant bypass solenoid??

I'd have to say you're right about that. Not sure why that would be on an emissions circuit but who am I to judge the Ford engineers lol. I taped it up and did some cruising around and haven't had it pop since. I'll try to look into a more permanent fix but this at least gets me to work.

 

[Nitelife]

Everything is tight/jumbled up under the intake tract and things can rub against each other causing exposed wires or vacuum leaks, for example. Glad you dug in and found the exposed wires and it seems to be working. Sounds like you fixed it. Let us know if it's permanent or something crops up down the road.