2017 Shelby GT350 Start Up

Caseindaplace

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*updated 11/18

The noise initially described below was indeed determined to be the exhaust valves needing a little lubrication. A follow up question regarding the exhaust valves is what would prevent them from cycling? Sometimes when I press the clutch pedal and wait, they do not do a full cycle. When this happens I’ll start the car and get a trunk ajar notification and the driver modes are unavailable. I did notice ONE time during this event (haven’t confirmed every time) that my driver valve was closed and passenger was open.

So either a computer error or a valve error.

Side note - the trunk ajar message also happens if I hit a bump occasionally, but the trunk is shut. Maybe a wiring issue or short?





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Need some advice. I was going to get under the car or under the hood and have the wife push the clutch for me to hear the noise but I figured I’d also ask the forum in the meantime.

I’ve got a 2017 GT350 I just picked up, awesome car. Drove 500 miles from Dallas to LA and still maxed on the oil so fingers crossed.

So when we sit in our Shelby’s (or any fob / push to start Mustang), you depress the clutch and well at least in the GT350 you hear mechanics moving I assume it’s like turning a key to the on position prior to cranking / turning it over. On mine I noticed when I push the clutch in, I hear a mechanical / rotational squeak for the short time it’s priming or doing whatever it does, then I push the start button and fires up (no squeaks or squeals like belts during operation). When I shut the car down, I hear the same mechanical / rotational squeak just for a shorter time right when it shuts off.

I have a video link below. The garage makes it echo very well to hear.

So what is moving or what process is happening when you are in the car with your fob and you push the clutch in prior to starting?


IMG_8684.JPG
IMG_8597.JPG



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Kobra Kai

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I hear the same thing in my 2019 GT350. To me, it sounds like something is opening and closing. Having said that, my guess is that it's the butterfly valves of the exhaust that are being actuated before start-up. Try recording the exit of the exhaust where you can see the valves. Overall, it's nothing to worry about.

Also, congrats on the new whip!
 

Caseindaplace

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I hear the same thing in my 2019 GT350. To me, it sounds like something is opening and closing. Having said that, my guess is that it's the butterfly valves of the exhaust that are being actuated before start-up. Try recording the exit of the exhaust where you can see the valves. Overall, it's nothing to worry about.

Also, congrats on the new whip!

Thank you! I will check into that as well. I was just thinking I needed to lubricate something perhaps?


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5.2Leader

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I always thought it was the flux capacitor! ‍♂️


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Caseindaplace

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The noise your hearing is the actuators to the exhaust opening and closing. It does this when you start the car.


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Would it be a computer issue if the car doesn’t open and close the valves every time? I’ve noticed more lately that when I push the clutch in the valves do not cycle and then I get the trunk ajar notification (it is closed) and can’t select exhaust or drive mode. I noticed this usually happens after the first start of the day so second start on after running errands etc.

I noticed the driver valve was closed and passenger was open.

It’s either a computer issue or valve controller motor issue but I’ve never had an issue opening and closing them if the initial cycle is done.


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JAJ

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So the way the valves work is this: the ECU cycles them on startup to make sure they're working. The controller motors on each one have a sensor that tells the ECU if the valve's moving or not. If "not" then it might lock you out of drive modes other than "normal" until you get it fixed. I say "might lock you out" because the original 2016 ECU software always locked you out, but newer ECU software will tolerate stuck valves on the assumption that it's cold, they've gotten wet and now they're frozen in place. There was a TSB on this. In any case, when they're working properly, if you start the car immediately when you push the clutch pedal down, you'll hear it start with the valves open. If you wait until the noise stops, it starts with the valves closed.

It sounds like you've got one or more stuck valves.

The trunk warning is a switch or a wiring harness problem and it's unrelated to the exhaust valves.
 

Caseindaplace

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So the way the valves work is this: the ECU cycles them on startup to make sure they're working. The controller motors on each one have a sensor that tells the ECU if the valve's moving or not. If "not" then it might lock you out of drive modes other than "normal" until you get it fixed. I say "might lock you out" because the original 2016 ECU software always locked you out, but newer ECU software will tolerate stuck valves on the assumption that it's cold, they've gotten wet and now they're frozen in place. There was a TSB on this. In any case, when they're working properly, if you start the car immediately when you push the clutch pedal down, you'll hear it start with the valves open. If you wait until the noise stops, it starts with the valves closed.

It sounds like you've got one or more stuck valves.

The trunk warning is a switch or a wiring harness problem and it's unrelated to the exhaust valves.

Gotcha. Usually on good days, first start, you hear it flux a few times it seems. Then sometimes after that start it will only flux it seems once like a quick half blip maybe. But even when that happens it’s fine so I assume that’s normal.

It’s only when you don’t hear it is it a problem. My driver valve rattles when closed anyway so I was trying to see if there’s a way to fix that loose valve or need a new muffler (with a new valve)? I assume removing the control motor to access the valve will not help?

The trunk issue I checked and saw that the harness has a weave around it BUT there was a small section with electrical tape on the exposed harness outside the carpeted trunk lid. This may indicate someone tried a fix? And it’s shorting? Thoughts? Maybe I should open it up and check for crimping or frayed wires




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trevman2

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The trunk issue I checked and saw that the harness has a weave around it BUT there was a small section with electrical tape on the exposed harness outside the carpeted trunk lid. This may indicate someone tried a fix? And it’s shorting? Thoughts? Maybe I should open it up and check for crimping or frayed wires




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Have someone manipulate the wires from inside the trunk while you are in the car. Make sure the trunk lid is closed to duplicate the same scenario. This might help troubleshoot a possible short if you can duplicate the issue.
 

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