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Mustang dies at higher rpm, and won’t even turn over for a few minutes

Okay hello, I have a 2007 mustang gt that I recently purchased, it was the guys daily, and it made a 4 hour drive home (with responsible driving) with no issues. The guy never said anything about it having an issue. (Of course) but it’s just odd that this is just now happening. The issue I’m having is that when I decided to take the car on some backroads, it would sputter out and die after or during some high rpm driving. Then it wouldn’t even turn over, like the starter motor wouldn’t even try. (However, the lights and sounds would still come on.) After a few minutes, it would start right back up like nothing happened.
My question is, could this be because it has a very cheap battery that can’t support high rpm on a v8? Or is it an ignition switch issue? Or maybe something else?
Btw idk what battery is in it, I’m out of state at the moment, but I’ll look soon.

Start with the basics. Clean both ends of both battery cables. Have your battery and charging system checked. Even after all that, you may have a bad battery cable, they should be checked. If your battery checks good and you are concerned about having the right battery, call a parts store and ask how many cold cranking amps you are supposed to have and compare to what you have. As soon as these basic things are taken care of, and it still acts up let us know to dig a little deeper.

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And whether or not you are getting a CEL.

A weak battery wouldn’t cause this, but one with bad connections or an intermittent internal short might.

Do the lights dim when you try to start it back up? Like it’s temporarily seized up?

If you can get this to happen whenever you want, get it to happen when somebody (e.g. a shop tech) can try to manually turn the engine with a socket/ratchet tool on the crankshaft bolt. If it turns freely then, probably nothing very serious. Otherwise the engine internals are binding up somehow, and further shop investigation is needed to determine why.

Assuming it’s not a binding engine problem, one idea is that the alternator is faulty and isn’t able to keep up with the current demands of the ignition module during high rpm driving. The result would be a discharged battery under high rpm operation, the engine spark gets weak, sputters and stalls, and won’t crank right away until the battery has chance to equalize. The higher the rpm, the more current is required. A good alternator should have no problem w/that b/c the higher the rpm, the more current the alternator can supply. Unless the alternator drive belt is slipping, so start by checking that. After that, connect up a volt meter to the battery and watch it as you drive at the higher rpms. It should maintain the voltage in the 13-15.5 volt range irrespective of rpm. I expect what you’ll see is the voltage dropping below 12 volts.

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Thank you so much, a very knowledgeable response. I think you’re onto it with the alternator. I’ll let you guess know what I find!

Do you hear any indication that the starter circuit has been engaged… A weak battery will cause this symptom up to a point… Your starter relay still has to function even at low batt levels… do you hear your starter relay engage? Do some measurements on your battery… record resting voltage and also the running voltage. See what you get. Your resting voltage can be 12.5-8 or so…and your running voltage can go as high as 14. Sounds like your battery is on the way out most likely.

One thing else you might consider. At high RPM as the valves start to float, the lifters will overfill with oil and hold the offending valve off the seat. As this happens to more and more valves, the engine will lose power and stall. When you try to restart, there will be no compression; the engine will turn freely; and not start. After a rest the lifters will leak down; allow the valves to reseat; and a regular start can be achieved.

The solution would be to install new, stronger, or shimmed up old springs. But, then you might be running into the red line of engine, risking catastrophic failure of other engine components.