Anyone have any ideas on this problem? FINALLY SOLVED

[Leigh_bullitt]

Hi
I have a 2020 Mustang Bullitt and have a strange intermittent problem since new.

when I cold start and drive the car it feels ok in the high rpm range cruising at lower rpm I get some surging and gives me foot ache having to keep touching the gas on and off.

however after driving and I leave the car for say 15mins the problem has suddenly gone and it doesn’t surge and the exhaust tone sounds strong again.

I’ve checked the data logs and everything is perfect fuel trims are bang on, Maf is perfect, fuel pressure normal.

any ideas what could cause this and cure this when I leave the car for 15 mins when hot ?.

cheers

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[JetGray_Mach1]

I do not have any of this issues. What rpms are you experiencing this? I am assuming this is the 6 speed?

 

[Leigh_bullitt]

Yeh, six speed.
Just seems to surge a lot at low rpms and it’s difficult to hold the speed. Higher rpm is ok although seems a little off power. Exhaust sounds slightly different too.
Will drive for an hour in this way. Stop the car for 10 mins and suddenly it’s running perfectly again. No surging and full power.
It’s really weird. Have had this since day one in 2020 till now

 

[ORRadtech]

Did you ever take it to a dealer for diagnosis?
You said you checked data logs. Is it tuned? Have you sent during and after logs to the tuner?
My WAG is something to do with the variable valve timing. I base that on nothing but a feeling that I have no explanation for...

 

[5doorsoffury]

is it stock? did you do a once over for anything loose on the intake? idle as a high vacume so maby a leak rears its head there idk.

 

[Leigh_bullitt]

Does it stock or tuned.
everything seems fine at the intake and idles perfectly.
it’s really strange..

 

[sk47]

idle as a high vacume so maby a leak rears its head there idk.

Hello; Decent thought. Cold will run a bit rich is my guess. Warm my close up a small vacuum leak???
Lazy sensor???

 

[Leigh_bullitt]

Yeh.
I think it has to be something like that. I think mechanically it’s running perfectly but almost feels like something isn’t allowing it to run well.

oil temp would be a culprit in these cases but I don’t think we have oil temp sensors on these cars ?.

 

[Leigh_bullitt]

I did recently get two error codes that showed up and then they disappeared again. They were :
P2453
P245F

 

[black22gt]

Both of those codes are for GPFs. Low pressure. I found a thread on it and quoted the OPs solution. I see you are in Spain so you do have the GPFs as far as I know.

Particulate Filter Pressure Sensor A/B? Circuit Range/Performance

https://www.mustang6g.com/forums/th...circuit-range-performance-malfunction.139011/

From thread:
UPDATE: Took the car to the dealership to have it checked out. They told me that this is a known issue and Ford has issued a service bulletin for it. Apparently one or both of the particulate sensors (on either side) can exhibit a faulty reading, in which case they automatically replace both sensors and they update the PCM (apparently there is some update in connection to this).

 

[ORRadtech]

Hello; Decent thought. Cold will run a bit rich is my guess. Warm my close up a small vacuum leak???
Lazy sensor???

If that were the case why wouldn't it spontaneously correct itself once the engine was hot? The OP says he has to shut it off and wait 15 minutes. Then it acts right.
The lazy sensor thought would fit better. It certainly seems like an electronic component kind of fault.
It feels like we're still missing information though.

 

[sk47]

It feels like we're still missing information though.

Hello; This is one of the problems of diagnosing a problem from a distance.

 

[Leigh_bullitt]

Yeh. Don’t think it’s the GPF because that only showed up briefly when I got the cat back fitted and hasn’t popped up since.
it’s definitely something electrical like a sensor or something

 

[Leigh_bullitt]

No codes via FORScan either but I can definitely feel a night and day difference as to how it performs on the road

 

[sk47]

it’s definitely something electrical like a sensor or something

Hello; some years ago a friend had a problem with a jeep. It would die randomly. He could let it cool down for maybe 20 minutes and it would start back up and run ok for a while. Turned out to be a crankshaft position sensor. Replaced that and it was fixed.
Do not get me wrong. I am not suggesting a random replacement of sensors. At least not right away. Some sensors can be tested I have discovered. A first thing I do on fuel injected vehicles is to clean all the grounds I can find. I check the condition of the wires and the plug-ins looking for corrosion and misalignments.
Still in the WAG state of guessing tho.

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