Open Loop issues- which sensors - Page 11 - Ford Mustang Forum
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post #151 of 196 (permalink) Old 02-14-2019 Thread Starter
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Since I haven't found hardly any topics related to the replacement of the 94-95 5.0 fuse panel,it would probably be a great addition to the forum if you take a bunch of pictures during the R&R of your panel so that others will have a good How To write-up on the project.That is,of course,if you don't mind doing it.Maybe the moderator will sticky it too,so it'll be easy to find.Eventhough Im not a 94-95 owner,Id be curious to see just how its done.If I locate something more relevant to the subject,I'll come back and drop a link.
I'll do my best. The guy on the phone I orederd it from said that it's not as intimidating as it seems, and that he sells 90% of those harnesses due to that stud.
I don't think anyone would really want to buy just the box and try to get the wires on to it. That looks like an even bigger headache. I looks like if you buy the whole thing with the wires attached to the box, it's just about matching up the electrical plugs.
The job kinda looks like it's gonna be a hand slicer though.

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post #152 of 196 (permalink) Old 02-14-2019 Thread Starter
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This is the type of rig I purchased from MPS
https://www.ebay.com/itm/1994-1995-F...IAAOSwWN9agMLJ

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post #153 of 196 (permalink) Old 02-14-2019 Thread Starter
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Man, I hope this cures a few ills. Surely so I'd think.
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I'm sure it will. Fixing such a critical connection will prevent some future troubles, too.

It's somewhat comforting to hear that you're not the first to experience this, but I'm kinda surprised not to have heard it around here before. Makes me wonder if mine's about to fail...

Can you tell how it failed? If you have to open it up in order to see, I'd recommend waiting until the replacement comes in so you know it's safe to crack into the old one. But when you get a chance, I'm really curious as to whether it -I dunno- corroded, or what. You don't suppose there's any chance that you ever overtorqued it, is there? I'm having trouble locating a torque spec for that stud, unless the manual is erroneously referring to it as a "Power Distribution Box Ground Nut" (91-122 pound INCHES). FWIW, the cable nut at the alternator stud is supposed to be 79-107 pound-INCHES, so that's gotta be close.

1995 Mustang GT (5.0), daily driver
1995 GMC C2500 (5.7), alternate daily driver
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post #155 of 196 (permalink) Old 02-14-2019 Thread Starter
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Quote:
Originally Posted by Urambo Tauro View Post
I'm sure it will. Fixing such a critical connection will prevent some future troubles, too.

It's somewhat comforting to hear that you're not the first to experience this, but I'm kinda surprised not to have heard it around here before. Makes me wonder if mine's about to fail...

Can you tell how it failed? If you have to open it up in order to see, I'd recommend waiting until the replacement comes in so you know it's safe to crack into the old one. But when you get a chance, I'm really curious as to whether it -I dunno- corroded, or what. You don't suppose there's any chance that you ever overtorqued it, is there? I'm having trouble locating a torque spec for that stud, unless the manual is erroneously referring to it as a "Power Distribution Box Ground Nut" (91-122 pound INCHES). FWIW, the cable nut at the alternator stud is supposed to be 79-107 pound-INCHES, so that's gotta be close.
I went and tried to take the bat and alt cable off of dads '97's box to see if the stud was loose as well. However, the nut didn't want to come off very easy, and I was afraid I would break the box. When I was torquing on the nut trying to break it loose it would pull the box down. I think the stud is on a plate and that plate is against the inside wall of the box. I bet at some point when the cable off the stud the torque broke whatever is on the inside wall.
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You'd think theres a metal plate of some sort,with all of the fuse slots built into it on top of the plate,that extends to the outer part of the plastic housing,where the stud is then attached?? Im with you Urambo & am curious as to why there are no threads or writeups about fuse panel replacement,if MPS states they sell alot of them due to the stud issue.
The damaged stud might have been causing the regulator to command full output of the alternator everytime the voltage dropped down really low.It would've caused alot of resistance in the circuit/cable too & this could have possibly been the reason for the alternator overheating?? I know if the engine is running and you remove the battery cable,to verify if the alternator is working, it'll trigger the alternator to output max power because it thinks the battery is totally discharged.On vehicles with coil packs or coil on plugs,if a spark plug is bad at a cylinder,it can cause enough resistance to kill the coil because of the coil working overtime to try and fire the plug,so if something is causing too much resistance in the alternator circuit,the alternator working overtime might create too much heat and also stop it from charging. When you would rev the engine up to 2500rpm,the additional voltage output was probably supplying enough power to defeat the resistance of the damaged stud to allow the engine to keep running,but once you slowed down to a stop & let it idle,it would try to stall since the alternator was now putting out less power, from idling.

It shouldn't be too bad of a job since the harness will come connected to the panel already & the other end of the harness will be plug n play.Good luck with the project.

1991 Mustang lx
D.S.S. 342ci {10.5:1}
TFS 190cc + track heat
Lunati 61011 .549".565"
Pro-M 76mm maf
Jetronic 30lb inj
QA1 Coilovers
17" Weld ProStar XP's
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Quote:
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I went and tried to take the bat and alt cable off of dads '97's box to see if the stud was loose as well. However, the nut didn't want to come off very easy, and I was afraid I would break the box. When I was torquing on the nut trying to break it loose it would pull the box down. I think the stud is on a plate and that plate is against the inside wall of the box. I bet at some point when the cable off the stud the torque broke whatever is on the inside wall.
I wonder if you could install one nut onto the stud and tighten it just enough to secure it then put the cable onto the stud and against the nut then install a second nut and tighten it lightly,then hold the bottom nut with a wrench while you tighten the second nut down firmly?? A locknut as the second nut would be even better at making sure it stays tight.

1991 Mustang lx
D.S.S. 342ci {10.5:1}
TFS 190cc + track heat
Lunati 61011 .549".565"
Pro-M 76mm maf
Jetronic 30lb inj
QA1 Coilovers
17" Weld ProStar XP's
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post #158 of 196 (permalink) Old 02-15-2019 Thread Starter
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The short positive battery cable that runs to the box has a little plate with a hole on one end that slides over the stud, and that plate sits in a slot on the side of the box. Just from looking at the top it looks like the stud is running into the the block the fuses sit in and isn't attached to the black box itself.
If one ever has to remove the small battery cable it might be a good idea to soak the nut that holds in on with some sort of penetrator first so it'll come off easier.
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post #159 of 196 (permalink) Old 02-15-2019 Thread Starter
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Man I hope the stud doesn't jiggle on the new box. I have it put back together so I can start it and move it if need be. The stud doesn't giggle with the cables tightened down.
I tested again. There's a metal plate on the outside of the box that the stud runs through. The volts jumped around there as well as on the nut that holds the cables down with the motor running. When the motor was off the volts held steady and read what the battery read.
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post #160 of 196 (permalink) Old 02-15-2019 Thread Starter
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Ok, so.. Was hanging with Dad and I probed his box, (gross)on his '97. The volts of course stayed steady (at the nut) and matched the battery. I tested my alternator where the power wire connects and the volts were 14. something and they did NOT jump around like it does on the end where it connects to the box.
When the motor is off the bat, the alt (at power wire) and the stud (and plate the stud goes throuh)on the fuse box all read the same 12.76 volts. When the motor is running all had like numbers except the volts would drop and raise at the box. It be 14v for a few seconds, drop down to 9-10, once I saw 5v, then back up to 14 for a little.
Surely/hopefully my problems lie within the box?
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Can you tell if the lower half of the stud is threaded or solid or does it disappear down into the plastic housing?? If its threaded,the threads could have stripped on the stud or in the plate.If its solid like a pin on the stud's lower half,it might have had a clip holding it in place that broke or popped loose.Are you gonna carefully hack your stock panel up for inspection once the new one is installed & working??

1991 Mustang lx
D.S.S. 342ci {10.5:1}
TFS 190cc + track heat
Lunati 61011 .549".565"
Pro-M 76mm maf
Jetronic 30lb inj
QA1 Coilovers
17" Weld ProStar XP's
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post #162 of 196 (permalink) Old 02-15-2019 Thread Starter
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Quote:
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Can you tell if the lower half of the stud is threaded or solid or does it disappear down into the plastic housing?? If its threaded,the threads could have stripped on the stud or in the plate.If its solid like a pin on the stud's lower half,it might have had a clip holding it in place that broke or popped loose.Are you gonna carefully hack your stock panel up for inspection once the new one is installed & working??
I believe the stud is threaded all the way. It has quite a bit of travel in and out of the whole as well as side to side. (That's what she said)
Yeah I'll see what the inside looks like once I'm up and running. I really hope the stud doesn't have any play on the "new" box. If it doesn't I think I'm on the right track. If it's loose I guess it's either made to be that way, or the guy sold me a bad box...
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Quote:
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Ok, so.. Was hanging with Dad and I probed his box, (gross)on his '97. The volts of course stayed steady (at the nut) and matched the battery. I tested my alternator where the power wire connects and the volts were 14. something and they did NOT jump around like it does on the end where it connects to the box.
When the motor is off the bat, the alt (at power wire) and the stud (and plate the stud goes throuh)on the fuse box all read the same 12.76 volts. When the motor is running all had like numbers except the volts would drop and raise at the box. It be 14v for a few seconds, drop down to 9-10, once I saw 5v, then back up to 14 for a little.
Surely/hopefully my problems lie within the box?
I think you are on the right track. The reason for the steady voltage while the engine is off is probably due to the absence of engine vibrations. If you could induce the same level of vibration somehow with the engine off, you would probably see that voltage flicker again.

1995 Mustang GT (5.0), daily driver
1995 GMC C2500 (5.7), alternate daily driver
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Quote:
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I think you are on the right track. The reason for the steady voltage while the engine is off is probably due to the absence of engine vibrations. If you could induce the same level of vibration somehow with the engine off, you would probably see that voltage flicker again.
Great point.

1991 Mustang lx
D.S.S. 342ci {10.5:1}
TFS 190cc + track heat
Lunati 61011 .549".565"
Pro-M 76mm maf
Jetronic 30lb inj
QA1 Coilovers
17" Weld ProStar XP's
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post #165 of 196 (permalink) Old 02-19-2019 Thread Starter
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Quote:
Originally Posted by Urambo Tauro View Post
I think you are on the right track. The reason for the steady voltage while the engine is off is probably due to the absence of engine vibrations. If you could induce the same level of vibration somehow with the engine off, you would probably see that voltage flicker again.
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Great point.
I hope you boys are right. I think surely that stud is gonna be the issue. The harnees & box haven't arrived yet, but I'm not in too big of a hurry to do the job. The weather stinks and it looks like it's kinda going to be a pain to do. There's quite a few plugs to unhook. I imagine I'll break a few tabs that hold them together.
I have these plastic pry bars that work well though. They work well for removing plastic push-pins
https://m.harborfreight.com/nylon-pry-bar-installer-kit-4-pc-63594.html?utm_referrer=direct%2Fnot%20provided

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