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Discussion Starter · #1 ·
As the title states, I've driven the car twice since flashing a revised tune. First time with sct connected. The car bucked hard, sct showed loss of comms, nothing else even flickered. Came right back, ran fine, and no code.
2nd drive, sct not connected. Car bucked hard, got p0600 and limp. Cleared the code and all was good. Both times were light throttle cruising within a few minutes of cold start.
Have been tuned for several weeks with no issues. Problem started after revision. Will flash to stock this evening and see what happens. Anybody else experience this?
 

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Discussion Starter · #2 ·
The way it acts honestly feels like a bad connection or a broken wire. I'm only mentioning the tune because that's all that's changed when the issue started.
Can anybody tell me the pin # for PCM power and ground? And if the PCM ground is a splice?
 

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Discussion Starter · #3 ·
Well hell...I just got called to savannah for an emergency plant shutdown. I'm in my service truck now, but it's gonna drive me nuts not being able to dig into this tonight.
 

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Discussion Starter · #4 ·
Yep, should've searched first. I'll check/repair/relocate all the grounds under the airbox before doing anything. I'd hate to be mid flash and lose comms. I've toasted a pcm on my old trans am because of flashing with a loose ground.
 

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Discussion Starter · #6 ·
Log and send to Torrie.
Really not thinking it's the tune at all. Just a screwy coincidence where a problem reared it's head right after an unrelated change. And after dealing with Torrie first hand, I have absolutely no doubt that if it turned out to be tune related, he wouldn't rest until it was 100%.
I got back from savannah @ 10pm and drove the car 30 miles from a cold start. Ran beautiful. That leads me to think loose ground/connection even more. I was already planning on pulling everything to get my driver side motor mount squared away, so I'll probably weld in a ground lug while I'm in there.
 

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No need to weld in a lug, just clean the paint and primer off. There is also a ground under the air box but I don't know what it's for. 15+ cars only have one under the battery box where the earlier models had 2.
 

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Discussion Starter · #9 ·
Might as well do the harness while your in there. @BlackT5 still got the pics?
Is it bad ground splices? If you tell me roughly where in the harness, I'll fix em myself. It's beginning to sound like I'll be making ground buses for this car like I do for all the race car harnesses I build. Btw, did you ever email me, @Slstomper ?
 

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Discussion Starter · #10 ·
A pcm pinout and ground distribution diagram would be awesome if anybody felt generous!
 

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Is it bad ground splices? If you tell me roughly where in the harness, I'll fix em myself. It's beginning to sound like I'll be making ground buses for this car like I do for all the race car harnesses I build. Btw, did you ever email me, @Slstomper ?
I never got the email from you. No there are 8 bad splices in the harness. You have to strip it from the head down to the ECU. Do the grounds also.

http://www.focusst.org/forum/focus-...ine-wiring-splice-repair-140.html#post1009821
 

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Discussion Starter · #12 ·

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Discussion Starter · #13 ·
@Slstomper email resent from my yahoo account. Check spam maybe.
 

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Discussion Starter · #14 ·
Got the 3 chassis grounds under the battery and airbox sanded through the primer and sorted out, made up a 6ga wire that ties the ground strap to the charging lug/negative terminal(which i had to sand through paint and primer), and filled the driver side mount with urethane. Found the locations for all the splices, so I'll be firing up the soldering station after work tomorrow. I'll probably make another negative terminal connection because that's a tiny ground wire for the amount of electronics on the car. Even more amazing is that the way the factory grounds are, there's little more than 3 spot welds grounding everything back to the battery.
 
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Got the 3 chassis grounds under the battery and airbox sanded through the primer and sorted out, made up a 6ga wire that ties the ground strap to the charging lug/negative terminal(which i had to sand through paint and primer), and filled the driver side mount with urethane. Found the locations for all the splices, so I'll be firing up the soldering station after work tomorrow. I'll probably make another negative terminal connection because that's a tiny ground wire for the amount of electronics on the car. Even more amazing is that the way the factory grounds are, there's little more than 3 spot welds grounding everything back to the battery.
we think a lot alike

http://www.focusst.org/forum/focus-st-maintenance/39126-your-car-might-have-ground-issues.html
 

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Might as well do the harness while your in there. @BlackT5 still got the pics?
The pics with all the splices lined up on the bench? I think I stumbled across it the other day.

By the looks of the post you probably don't need them anymore.

Remember when we cut on apart only to find that they smashed the copper together and glued? WTF were they thinking?
 

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Discussion Starter · #18 ·
Lol, it would appear that we do!

I didn't get into the splices yet since I just found out I've only got 1 day off for the next 3 weeks. Just fixing and modifying the couple grounds I did made a HUGE difference in the car! Even with the e rmm and both side mounts completely filled with urethane, the car has never idled so smoothly. All my log readings are notably smoother. I know it's not super accurate, but my avg mpg went from 27.6 - 30 according to the dash (that's a true avg too, my commute is 50/50 highway, hills, stoplight drags, and cruising)
Won't call my p0600 problem resolved until more time passes, but my car is Def happy with the better grounds.
 
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