23 GT M6 - 3.55 to 4.09 - Help Needed! - P086E

[Kreasen]

Just made the changes in ForScan. The Axle Ratio was set to 494.xxx which seems odd. I adjusted it to 4.09 so we'll see what happens in e next 30 miles.

On Forscan should it not be 4.090 as apposed to 4.09.


I did an axle swop from 3.55 to 3.31, I was having an issues where the car would have no power in 3rd gear around 2-3000rpm
I was able to successfully change the axle ratios using Forscan.
First I updated the BCM with the new ratio, and then performed a PCM relearn.

One other thing to note when I read the axle ratio using forscan it said 3.550 so I updated it to 3.310

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[Berserk]

On Forscan should it not be 4.090 as apposed to 4.09.


I did an axle swop from 3.55 to 3.31, I was having an issues where the car would have no power in 3rd gear around 2-3000rpm
I was able to successfully change the axle ratios using Forscan.
First I updated the BCM with the new ratio, and then performed a PCM relearn.

One other thing to note when I read the axle ratio using forscan it said 3.550 so I updated it to 3.310

I can take a look at that. What does a PCM relearn entail?

 

[Kreasen]

I can take a look at that. What does a PCM relearn entail?

On Forscan first update the BCM with the new ratio,...then go to Configuration and Programming -> PCM relearn vehicle data.

 

[Berserk]

On Forscan first update the BCM with the new ratio,...then go to Configuration and Programming -> PCM relearn vehicle data.

I set the tune back to stock, checked the BCM and it was still at 4.090, did the relearn. It immediately is throwing the same errors again instead of after about 30 miles. About to give up and go back to the stock ring and pinion.

 

[Superspirit]

There are several threads on here, this can't be done with forscan. It can be done in a tune. The ford performance tune gives you the option.

 

[K4fxd]

If you are getting P086E it is the neutral position sensor circuit, nothing to do with the rear gear. Sorry I didn't look up the trouble code earlier.

P086E
Meaning	Neutral position sensor A circuit intermittent/erratic
Possible causes	Faulty neutral position sensor, loose or corroded wiring, faulty transmission control module, or mechanical issue with the neutral position sensor mechanism

Some 2019–2020 Mustang vehicles with a 5.0L engine and manual transmission may exhibit a malfunction indicator lamp (MIL) with DTCs P086A–P086E, P08AE–P08AF, P08B0–P08B2, P095A–P095D, and other DTCs. These vehicles may also have an inoperative reverse camera and reverse lights, and the IPC may display messages warning that various driver assist systems are not available.

 

[Berserk]

If you are getting P086E it is the neutral position sensor circuit, nothing to do with the rear gear. Sorry I didn't look up the trouble code earlier.

P086E
Meaning	Neutral position sensor A circuit intermittent/erratic
Possible causes	Faulty neutral position sensor, loose or corroded wiring, faulty transmission control module, or mechanical issue with the neutral position sensor mechanism

Some 2019–2020 Mustang vehicles with a 5.0L engine and manual transmission may exhibit a malfunction indicator lamp (MIL) with DTCs P086A–P086E, P08AE–P08AF, P08B0–P08B2, P095A–P095D, and other DTCs. These vehicles may also have an inoperative reverse camera and reverse lights, and the IPC may display messages warning that various driver assist systems are not available.

I've looked this up and tried to find out what the heck it is, where it is at, etc and found literally nothing. There was a Ford PSB regarding the 2018-2020's regarding this but nothing newer. Then every other post you hear about regarding this is related to a tune fixing the issue that somehow Palm Beach Dyno isn't aware of. I've seen one thread where Steeda fixed it. I reached out to them but the guy just pointed to the 6 year old PSB. idk about to switch back to 3.55.

 

[WildHorse]

you'll get DATA mismatch code, like a U0422 if it's not recognizing the new ratio.

 

[K4fxd]

P061B is the most common tune related error. I misread yours to be that.

Ask your tuner to shut off the P086E code. It has nothing to do with emissions. If you are auto I'd check the wiring to and from the transmission. I'm not sure where the neutral safety switch is but it is obviously noisy on the circuit. If manual, mine is auto, I've never tried to start one in gear on a test drive so I don't know if a neutral switch is in a manual. Could be a clutch sensor going bad and road vibration causing it to trigger the code.

I guess what I'm saying is swapping back to 3.55's most likely won't fix it.

 

[WildHorse]

I've never tried to start one in gear on a test drive so I don't know if a neutral switch is in a manual.

It's called a clutch safety switch, you can start it in any gear as long as the clutch is depressed, otherwise it won't start.

O/P ... ever get a p170a ?

 

[Berserk]

P061B is the most common tune related error. I misread yours to be that.

Ask your tuner to shut off the P086E code. It has nothing to do with emissions. If you are auto I'd check the wiring to and from the transmission. I'm not sure where the neutral safety switch is but it is obviously noisy on the circuit. If manual, mine is auto, I've never tried to start one in gear on a test drive so I don't know if a neutral switch is in a manual. Could be a clutch sensor going bad and road vibration causing it to trigger the code.

I guess what I'm saying is swapping back to 3.55's most likely won't fix it.

It's called a clutch safety switch, you can start it in any gear as long as the clutch is depressed, otherwise it won't start.

O/P ... ever get a p170a ?

PBD stated that code is already disabled and it's still coming up. I've never gotten the P170A before.

My car just spent 2 weeks at the dealership for this and a rattle noise coming from the engine bay which I didn't think was "coyote tick" but maybe it is. It sounds exactly like the clip below but louder in my car. Which to me isn't a tick and is 100% a rattle but what do I know.



This video talks about how the intake manifold is likely making that specific rattle noise:


EDITING: The funny thing is I specifically asked them to replace the intake manifold and the shop foreman came out to listen to the car they all identified that it "was not normal" and after checking the paper work the intake manifold wasn't replaced or even talked about. I'm sorry to any service advisors but I've never had a good experience with any of them. I don't want a fucking middle man between me and the mechanic that seems to not know anything in general about cars. I want to talk to the person who is actually working on the car. I want to take a drive with them and experience my concerns with me in the car...

Anyhow, I also brought the car in for a very clear exhaust leak / noise and "they didn't hear anything". If you like cars at all you can tell my car has an exhaust leak in it somewhere. Once in a while I can quite literally hear the metal pipes sliding in and out of each other making a screech / squeak noise, let alone the sound of the actual exhaust / air.


This post his a mess of my thoughts as I'm going over this crap again and again. The tech after speaking with Ford themselves on a hot line mentioned a couple other cars had this exact same experience and the only fix for them was returning the car to the 3.55 gears. The shop that installed my 4.09 gears stated they would put the 3.55's back in free of charge but fuck are they fun... and just wake the 2023 up so much. I honestly didn't think they would find anything out in regards to the P086E code but really wanted them to just tighten up my exhaust and replace my intake manifold like I specifically asked them to do...

Oh not to mention that they delivered my car back to my house with 2 miles until E and I live in an area where the closest gas station is 12 miles away. I had to go get gas in my other vehicle in a gas can and bring it home just to make it to a gas station.

I've just been ranting at this point but still praying there is a secret way to keep my gears that someone knows. Palm Beach Dyno, Lund, and Steeda all say that this has nothing to do with the tune and it's a "hardware" issue. I'm not sure if swapping gears to 4.09 or above is just super rare in these models and they've not run into it before but that seems a bit far fetched or if the dealer is again just not finding something as they seem incompetent.

Also to note. They replaced the PCM in an attempt to resolve this code but it came back. When I got the car back I went into Forscan and changed the Axle ration to 4.09 again wrote it, then did the initialization step. Now instead of getting a bunch of lights / code after 30 miles. I don't get a code seemingly ever, but certain features are turned off still but not all the same.

Backup cam works
Exhaust selection works
Drive modes do not work
traction control is off permanently
some driver aids etc are off

When the code popped before the backup cam, exhaust, etc all don't work.

Cruise never works still...

 

[Cobra Jet]

The rear gear ratio is defined in the BCM, and the PCM learns it from the BCM. I believe you can use Forscan to program the correct ratio into the BCM and the PCM should correct itself. The other option would be to flip the switch in the tune for final drive ratio from "learn from BCM" to "Calibration" and put the correct value in the calibration. If your tuner can't do this for you, then you shouldn't be paying them.

As stated in engineering Mike’s post, there is a procedure that has to be followed; if it’s not followed in steps as it needs to be, then there’s going to be programming issues or issues with the expected results.

This thread discusses the 4.09’s - however if one were to go to post #78 another user outlined the exact tuning/programming steps needed after physically changing the rear gear hardware. His example is for 4.56’s, but try doing the same exact steps he did to see if you can overcome the issue you’re experiencing:
https://www.mustang6g.com/forums/threads/2019-up-4-09-rear-gear-swap.175422/

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What brand rear gears were used for the upgrade?

What rim/tire sizes are you running at front and rear?

Did you buy the car new or used? What dash cluster did your car come with? I ask this question because IF the vehicle came with an analog cluster and it was swapped over to digital, maybe there’s some other underlying issue occurring with the attempted “tunes”.

Have you checked any other wheel sensors or sensors that feed the logic back to the PCM/BCM for vehicle speed/rpm/rear gear/tire sizing data to ensure there is not an issue with the wiring or the actual sensor(s)? That would be the “hardware” to check IF you still cannot get the vehicle to act accordingly AFTER doing the “tuning” steps.

Other then the above, that’s all I have to offer because there’s many folks on here doing gear swaps and haven’t run into any modified software updates for the correct gear ratio all the way up to 4.56’s.

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