Top end feels flat

[bms44]

Afternoon all, I posted in the UK section but wanted to ask the Bullitt section as well. I recently purchased a 2020 Mustang Bullitt and I’m thrilled with it however I took it out today and it felt unusually flat at the top end, 5500rpm+
Like it would build power and torque normally until 5500 then just plateau instead of building.

just wondered if anyone could give some advice before taking it to a garage.

cheers.

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[robvas]

Do you have any way to datalog it with a tuning or obd2 device? Misfire code? Stuttering because of a bad coil/plug? Bad fuel?

Has anything been done to the car at all recently?

 

[bms44]

I’ve no way of data logging. Its recently had a H pipe fitted but that’s it. Ill test it tomorrow and if it persists ill ring the specialist garage.

 

[17MagMetal]

Any mods? On road these cars get hilariously sketchy past 4500-5500. Definitely not normal.

 

[bms44]

Just a H pipe, I’m thinking potentially it’s just some poor fuel, the issues started right after filling.

 

[Topdown]

Just a H pipe, I’m thinking potentially it’s just some poor fuel, the issues started right after filling.

Sounds a lot like mine once i got an H pipe it seemed to lose some HP. To be honest i find the Bullitt (19) not that quick. Ive got 21GT convertible as well and that really pulls. The Bullitt replaces a Stinger GT (2) and that was way quicker as well. I vary the fuel so its not that, but is definely a sluggish car

 

[Mach VII]

What octane fuel did you add?

 

[Nightmonkey]

RHD, right?
Maybe the RHD exhaust manifolds are the reason?
Not sure, if RHD got a different tune from factory because of the RHD modified manifolds?

 

[raptor17GT]

OP says it felt unusually flat after filling up so RHD / LHD in this instance makes no difference. Any update OP ?

 

[WD Pro]

OP says it felt unusually flat after filling up so RHD / LHD in this instance makes no difference. Any update OP ?

Yes there is defo a very clear difference between bottom end (below 4.5k) and top end (above 4.5k) on a RHD gen3.

If the OP regularly uses the top end, it would be blatantly obvious if something was amiss / different than normal

As a fist step (steps), I would fill (from empty) the tank with quality fuel, do a KAM reset, then take it for a little test drive.

WD

 

[bms44]

Sorry for the slow update, I was advised to refill the tank with V power and drive through that tank. I don’t want to jinx it but it actually seems to have worked, top end feels as it used to. Not sure if that means it was just a bad fill up or something else but as of yesterday it felt normal which is great as the top end is one of the reasons I love it.

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