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Sadly not. But today I just happened to open up my engine compartment fuse box. There's debris inside, looks like the lid hasn't/wasn't sealed correctly. Could this have been the cause of my issue all along? Debris and grim is close to the front end of the box, where the ECU/PCM relay and fuses are...

Can it really be that simple? I don't want to pull any fuses out, as it looks like there could be corrosion/don't want them to snap.

Surely any fault in the fuse box though would throw a code?
Yea my fuse box was dirty as well, I fully cleaned it along with the fuses didn’t do anything, I’m thinking it’s either map sensor, throttle body, or fuel pressure sensor or could be the crank sensor or physical engine timing, did you have a front cover leak fixed recently because I have and that’s what I’m thinking when this started
 

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2017, Mk3 Focus RS. Stock, for now!
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Discussion Starter · #102 ·
Yea my fuse box was dirty as well, I fully cleaned it along with the fuses didn’t do anything, I’m thinking it’s either map sensor, throttle body, or fuel pressure sensor or could be the crank sensor or physical engine timing, did you have a front cover leak fixed recently because I have and that’s what I’m thinking when this started
Ah I see.

To save you some bother, I've replaced so far (and it's made no difference, issue still persists)

Fuel rail pressure sensor
Knock sensor X2
Throttle body
Front o2 sensor
Evap purge valve

I did pull the MAP sensor which also has the temp sensor in it and ran the engine, it was still doing the issue even without the sensor plugged in

I'm total stumped too, no fault codes at all except a speaker ground code, but I doubt an infotainment issue would affect car running. Seems to be intermittent fault with 1 if the speakers too (fault to ground).
 

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Ah I see.

To save you some bother, I've replaced so far (and it's made no difference, issue still persists)

Fuel rail pressure sensor
Knock sensor X2
Throttle body
Front o2 sensor
Evap purge valve

I did pull the MAP sensor which also has the temp sensor in it and ran the engine, it was still doing the issue even without the sensor plugged in

I'm total stumped too, no fault codes at all except a speaker ground code, but I doubt an infotainment issue would affect car running. Seems to be intermittent fault with 1 if the speakers too (fault to ground).
What are your fuel trims? Do they improve with boost mine do. Also does it idle and come down to idle perfectly if you disconnect the upstream o2 because mine does. Did you ever have work done to it at the dealer or what not?
 

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Discussion Starter · #104 ·
What are your fuel trims? Do they improve with boost mine do. Also does it idle and come down to idle perfectly if you disconnect the upstream o2 because mine does. Did you ever have work done to it at the dealer or what not?
Yeah, with load the car seems all good to be honest. Just at idle there's issues. Or if the A/C is off, then it idles high for some reason

Not tried that with not having the O2 sensor plugged in

And yeah all work done at ford. They even tried ford technical, but they couldn't figure it out. Next steps was to get a field engineer out from ford, but apparently that was going to be mega money. Not done anything with it in a bit tbh
 

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Yeah, with load the car seems all good to be honest. Just at idle there's issues. Or if the A/C is off, then it idles high for some reason

Not tried that with not having the O2 sensor plugged in

And yeah all work done at ford. They even tried ford technical, but they couldn't figure it out. Next steps was to get a field engineer out from ford, but apparently that was going to be mega money. Not done anything with it in a bit tbh
Just replaced the fuel sensor and fuel trims seem to be better, comes down to idle a bit slow still and can sometimes stop and settle at 1200 but idk it’s kind of inconsistent.
 

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Discussion Starter · #106 ·
Just replaced the fuel sensor and fuel trims seem to be better, comes down to idle a bit slow still and can sometimes stop and settle at 1200 but idk it’s kind of inconsistent.
Yeah, mine is also super inconsistent. I think that's what makes it hard for the dealer to diagnose as they won't spend long on it
 

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Discussion Starter · #109 ·
Have you messed with the pcv ?
no, but I did manage to do a datalog with forscan today. but I have no idea how to interpret whats wrong.

i used the data to pull a graph of rev/time, and plotted revs desired by the PCM (REVDSD) and actual revs (RPM)

see below - Houston, we can see the problem.

I'll post the link to the full datalog excel here, if anyone has any experienc interpretting these, i'm open to any opininions!

Datalog sharing folder - Google Drive


Rectangle Slope Plot Line Font
 

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no, but I did manage to do a datalog with forscan today. but I have no idea how to interpret whats wrong.

i used the data to pull a graph of rev/time, and plotted revs desired by the PCM (REVDSD) and actual revs (RPM)

see below - Houston, we can see the problem.

I'll post the link to the full datalog excel here, if anyone has any experienc interpretting these, i'm open to any opininions!

Datalog sharing folder - Google Drive


View attachment 363994
Yea your fuel trims are high positive, seems like we have that same issue although the fuel rail pressure sensor helped my fuel trims but they can get stuck if I rev the engine or come to a stop light
 

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no, but I did manage to do a datalog with forscan today. but I have no idea how to interpret whats wrong.

i used the data to pull a graph of rev/time, and plotted revs desired by the PCM (REVDSD) and actual revs (RPM)

see below - Houston, we can see the problem.

I'll post the link to the full datalog excel here, if anyone has any experienc interpretting these, i'm open to any opininions!

Datalog sharing folder - Google Drive


View attachment 363994
Did you ever have the front cover removed for any reason? Mine was recently removed so engine timing may be the problem and or cam timing idk…
 

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Discussion Starter · #112 ·
Did you ever have the front cover removed for any reason? Mine was recently removed so engine timing may be the problem and or cam timing idk…
Would have been a couple years ago, but I've been having this issue for a few years right enough.

Wonder if there's a way to datalog to identify it as a timing issue. But then the cars are meant to have variable timing so should it not sort it out minor discrepancies by itself? So lost here 😂
 

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Would have been a couple years ago, but I've been having this issue for a few years right enough.

Wonder if there's a way to datalog to identify it as a timing issue. But then the cars are meant to have variable timing so should it not sort it out minor discrepancies by itself? So lost here 😂
The problem is that I I unplug my second brand new wideband the car idles and revs perfectly so that’s why I’m so confused
 

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Aaah I got you. Sorry 🤦😂
So high fuel trims can either be (after all the parts we replaced and no difference) an exhaust leak( car idles perfectly with front o2 unplugged, so confusing), a vacuum or internal vacuum leak(pcv, evap), or physical engine timing( which I think could be the problem honestly knowing techs at ford), sensors are usually pretty good at setting a code if they go bad so I don’t think that’s the problem considering it idles perfectly with no wideband. The car is capable of idling and driving fine with no wideband so I’m thinking a short or electrical issue to do with the wideband or something could also be the problem…
 
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