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2018 Mustang GT Wont Run

ugstang17

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Oh okay. Likely rules that out then. PM sent btw. Thanks for getting back.

PS - Check your alternator output at the battery for AC ripple. With the battery having a shorted cell pulling that hard on the alternator it could have compromised the regulator circuit. Just for safety sake take an AC ripple measurement on the system at the battery. Commonly less than .500vac (500mvac) read with the engine making 3000 RPM is acceptable. I could find no spec in the 2005 or 2011 Ford Mustang GT manuals on the charging section with respect to that check so I can only go on the standard I found on line when doing a general search on testing alternators in general.
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ahl395

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Finally got the car put back together this afternoon. For the first time since I bought the car, the dash battery voltage is reading over 14V. The car used to only read approx 13.5v prior to this cluster F**k. In fact, I had previously taken my car to the dealer because I was suspicious of a charging/battery issue. They said my dash voltage was normal and everything checked out fine so I didn't think much of it. Fast forward to today and the car runs flawlessly. Literally better than it has ever ran since installing the supercharger. I honestly think the bad cell in my battery was causing all kinds of havoc with the car, including the tune. I'm using the same file as before, except now the transmissions is behaving pretty much like stock without all the little quirks that drove me (and Rob Shoemaker) nuts. I'm smiling ear to ear, but at the same time frustrated that the dealer failed to diagnose such a simple problem.
The meth system is installed and ready to test as well. I'm going to pick up some M1 next week and see how it goes. Again, thanks much to Brent Davis for the tip on checking the battery! I don't think my dealer would have ever figured it out since the car cranked normally.
Glad your problems are fixed!

FWIW These cars have a "smart" battery management system, so depending on if the battery needs the charge or not the voltage will change as needed. So don't be alarmed if you see it in the high 12s while driving.

Anything 13+ its very unlikely low voltage caused any problems with the tune/transmission, but disconnecting the battery would have reset all the "adaptive learning" in the PCM and that probably is what fixed that issue.

Oh okay. Likely rules that out then. PM sent btw. Thanks for getting back.

PS - Check your alternator output at the battery for AC ripple. With the battery having a shorted cell pulling that hard on the alternator it could have compromised the regulator circuit. Just for safety sake take an AC ripple measurement on the system at the battery. Commonly less than .500vac (500mvac) read with the engine making 3000 RPM is acceptable. I could find no spec in the 2005 or 2011 Ford Mustang GT manuals on the charging section with respect to that check so I can only go on the standard I found on line when doing a general search on testing alternators in general.
If you take it to Autozone I believe their tester checks the alternator for ripple. It's probably fine though.
 
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Chris Barnes

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Thanks for the tips guys. I'll get it tested for the heck of it. Car is running great!
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