Newbie Question About Cruising in 6th Gear

[Oilspot6G]

Hello members!

Back in March we purchase our first Mustang GT (its also a convertible, with MT). Its a 2021, and had less than 2k miles at time of purchase. We just got back from our first big road trip (2,500+ miles).

One thing I noticed in traffic or slower speeds: If I didn't downshift right away and just tried to slowly accelerate in 5th or 6th gear - the engine would lug slightly: and that's pretty normal. However, If I tipped the throttle more aggressively, the car would shake like it was misfiring. Obviously, I would downshift at that point; but is that behavior fairly normal? This is my first V8 with MT. All other times it seems to purr like a kitten or roar like a lion.

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[NGOT8R]

Sounds like you were lugging the engine (not a Good thing to do). You need to downshift as you said, in order to get more rpm. I very seldom use 6th gear on the highway at all. Heck, sometimes I don’t even use 5th on the highway if the speed limit is 55-65 mph.

The more you drive your car, the more you’ll get a better feel for what each gear is capable of. Try this, the next time you’re on the highway, shift into 4th and stay there at highway speeds. This won’t hurt the car or transmission one bit. The only downside to it would be increased rpm, which in turn would burn more fuel.

 

[WItoTX]

Agree ^^^. Downshift, go. Shoot, in my car, if I am not doing 80, it doesn't have enough power to do much if I get on it.

 

[WD Pro]

6th ? I think I've only tried it once, and that was only check Ford didn't forget to fit it ... lol

(I don't sit on the motorway much, and euro's get the crazy 3.55 diff)

WD

 

[loucas-2021]

I use 6th when I'm going 80 no problem. However, I don't lug the engine. Op should be able to drive in 6th if desired just don't slam the accelerator pedal unless you're above 3500 RPM.

 

[RowdyRam]

I use 6th when I'm going 80 no problem. However, I don't lug the engine. Op should be able to drive in 6th if desired just don't slam the accelerator pedal unless you're above 3500 RPM.

Agreed. I use 6th on the 12 mile interstate stretch I use for commuting to/from work, but usually only if it won't drop the RPMs below 1700-1800. a quick downshift to 4th if I want to pass and just roll on easy. That is more than enough to handle any traffic issue, unless the guy I'm passing speeds up aggressively. I commute in Houston, after all

 

[Magnetic Stang]

Keep in mind 5th and 6th gears are over drive gears on your MT-82. The more you drive it the more you get familiar with what gear your car like at what speeds. Easy rule of thumb is if your RPM's are 2k or under and and you want to accelerate you need to down shift. These manual cars seem to love it at the 3k to 4k RPM though.

 

[sms2022]

Yep 3500 rpm is the sweet spot for accelerating. That’s a downshift from 6 to 4 at 70mph

 

[sms2022]

The 4.09 gears help a lot with this too, makes for 5 usable gears instead of 4

 

[loucas-2021]

Agree with this. The car shaking is not normal. Wonder if the exhaust tone changes under those conditions.

 

[joe603]

I noticed this too...my last manual car was a 2005 G35, so it's been a while. The GT doesn't like to accelerate in 6th, it's more of a maintain speed on the HWY gear. So ya, downshift to at least 5th depending on how you want to accelerate. Another odd thing I noticed is that when using adaptive cruise, it doesn't shake. I'm still amazed that I can shift and keep my cruise setting the same...very cool!

 

[gsxr1300]

The shake was probably because the rpm was to low and the engine was about to stall.

 

[AZ_Ryan]

Folks, he bought his car with 2k miles on it and took a road trip. It's not a warn clutch lol.

Any car will shake a little If you accelerate in a high gear at low RPM (also known as lugging the engine). Especially if you have a lower gear ratio. Theres nothing abnormal about it.

The OP just needs to learn to downshift.

 

[ShadesOfBloo]

Hello members!

Back in March we purchase our first Mustang GT (its also a convertible, with MT). Its a 2021, and had less than 2k miles at time of purchase. We just got back from our first big road trip (2,500+ miles).

One thing I noticed in traffic or slower speeds: If I didn't downshift right away and just tried to slowly accelerate in 5th or 6th gear - the engine would lug slightly: and that's pretty normal. However, If I tipped the throttle more aggressively, the car would shake like it was misfiring. Obviously, I would downshift at that point; but is that behavior fairly normal? This is my first V8 with MT. All other times it seems to purr like a kitten or roar like a lion.

What "slower speeds" are you using 5th or 6th gear?
The owner's manual has recommendations for what speeds to shift up. It says you can go into 5th at 41mph, and it doesn't promise you can accelerate.

5th gear at 41mph puts your engine under 2000rpm, probably for the sake of gas mileage. Giving it too much throttle at low rpm probably confuses the engine computer.

Remember, we have a "drive-by-wire" throttle, so your gas pedal is just an input device. Throttle response depends on electronic maps of various parameters and, from the factory, it's tuned for emission control and fuel economy as a high priorities.
My impression from my 2 drive-by-wire cars is that the throttle maps at low rpm with a load (esp. in high gear) aren't sorted well. Not for the driver's benefit. Besides the mechanical components (flywheel, clutch, etc) that's one more thing that can cause your engine to misbehave.

My Mustang can be in 6th gear, and go uphill at 1500rpm, but I'm darn sure not asking it to accelerate.

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