Tire Pressure anomaly

[Alan Applegate]

I was sitting in the garage to day testing out a few MP4a Dolby Digital (Special Audio) Apple Music files. Surprisingly, they sound better than I expected them to after a few minor setting changes, but that is a story for another time.

While I was messing with the dash, I noticed the tire pressures were all 27 psi on the dash and Ford Pass as well. Odd as it sounds (no pun intended), no warnings of low pressure over the last several weeks. I decided to recheck them manually using my calibrated Brookstone gauge (left over from my racing days). They all measured 31 pounds. That is about right, as I set them at 32 psi about a month ago when it was a bit warmer.

My Ranger’s tire pressure warning system always let me know if the pressure was under 32 (35 recommended). With the Mustang's tire pressure 5 psi under the recommended, I’m beginning to wonder if the system is working as it should?

Anyone else have a similar issue?

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[smurfslayer]

It does work. I holed one of the OE Trofeos about 5 days back and was watching the psi drop precipitously... I got the alert about 26psi, maybe 25.

Good news: the supplied air compressor works. It’s not fast, but it works.
Better news: I had already taken delivery of my aftermarket spare so I was prepared if I needed.
mo’ better news: I was spitting distance from my servicing stealership who plugged the already shagged tire in lieu of tomorrow’s replacement.

You probably need to drive and get the wheels turning to get a fresh reading.

 

[The Ghost]

I've noticed what the car says (as well as the FordPass app) is sometimes different from what is actually measured by manually checking the car. Not by a lot, but by 2lbs or so.

 

[dusman59]

Car and Ford pass read 32 cold. My three different gauges would read very close. One digital reads 32.1. Second analog reads 32. Third stem gauge reads 33. All my gauges are new with high ratings on Amazon. I had two older gauges (at least 35 years old) that were analog that would read 3 to 4 pounds low.

 

[Skye]

If not checking manually, I feel the best alternative is using the TPMS readout while the car is on and moving. Updated readings should be available within the first 100-200 yards, 91-182 meters.

What follows are some of my comments from a previous, thread.

https://www.mustang7g.com/forums/threads/tire-psi.161473/page-2#post-3301949

Near the end I highlight some differences and changes with recent updates to the FordPass App.

When I check pressures, I check them manually, using an AutoMeter 2160 gauge. It's a simple, well-built, analog gauge. Some like digital gauges.

https://www.autometer.com/performance-analog-tire-pressure-gauge.html

As virtually every run involves spirited driving, I check pressures often. Once a week, before driving, in the morning. There's a lot of construction in my area. While I've been fortunate, it gives me confidence to check this way.

Occasionally I'll look at Ford's TPMS numbers, as a reference. But as they round up and down, I prefer looking at the gauge. But this also leads into the topic you're interested in: how things update.

In the last year and with the most recent Ford Pass App update, I've noticed some changes.

As a reference for those unaware, TMPS sensors in the wheels have two parts: and accelerometer and a battery. What most often happens is, as the wheel spins, the sensor is turned on, supported by the battery, the wheel and vehicle then interacting. But I've also noticed with my vehicle, the battery will power the unit and respond to the car if the car queries it while sitting.

Different vehicles have different behaviors. My DD has to be running and moving for anything to update. But it's an older model from another vendor.

In the past, the car could be sitting stone-ass cold, not driven for days. I'd open the App, down-swipe, hear the car toggle, updating. I could get current TPMS readings. And current fuel and OLM. Now? No. Nothing updates.

Car sitting, unlocked. I'm actually checking this now. Nothing is updating. My readings are what they were shortly after my last run.

Car sitting, me in the car, Accessory mode active. Yes. Information updates. And that makes sense. The car is on. Takes a few moments as the car settles into this mode.

Car running. Yes. Same as above. After a few moments, everything is updated, driving or sitting.

All the above is my experience with a 6G car and the Pass App, v5.4.0 .

Why the change in behaviors? I suspect it has to do with newer Ford models and parasitic losses on the batteries. The latest generations of vehicles have more electronics than ever. IDK how much I was dragging the battery using the app before, but Ford's stopped that. At least for now.

People are constantly on their phones and doing all kinds of stuff. Maybe Ford realized some owners had the app open and it was always updating. IDK.

I have recently confirmed Ford is still updating the app and different features. For example, we used to be able to add service records, via the app and at this site: https://www.ford.com/support/

We knew they took that feature away from the app. I've since learned they took that feature away from the main site. Initial feedback from Ford is they do intend to bring the add service record feature back. IDK when.

https://www.mustang6g.com/forums/threads/tpms-change-parameters.205565/#post-4118501

A long read of TPMS research I'd done previously.

 

[GO FSTER]

I know you said it is a calibrated gauge from when you raced, but if it is old it may not be reading properly. I had a similar issue when I got my car. The app and car said the tires were over inflated. At first, I thought maybe there was a calibration offset somewhere in the settings, but couldn’t find anything. My other vehicles have a calibration button you use once you set the pressure to tell the car that it’s set to the correct level. But those systems aren’t as accurate with reading out the exact pressure, they use the ABS system to check for tire pressure differences rather than an actual sensors . I grabbed the gauge in my garage I have had for a long time and adjusted them but they still read high. At first I thought it was an issue with the car but since they were all high and reading the same the chances of all sensors being faulty were low. I figured it must be an issue with my gauge. I went and grabbed a new, good quality gauge and sure enough the car was reading right. I adjust them with this and hasn’t been an issue since.

 

[Wiley Marmot]

The TPMS on my GT always reads 3 lbs lower than my air gauge (all four tires), and it's not unusual to see a 1 lb difference in cold pressure between the rear tires; which will equalize as soon as I've backed out of my driveway and driven an 1/8 mile or less.

I'm considering disabling the TPMS altogether as I got by without one from 1970-2013 and never got caught out by a significantly low tire pressure.

Yes. I'm OC about tire pressures.

 

[Lakersfreak]

just a slight tangent....what psi do you guys keep your tires at?

 

[smurfslayer]

just a slight tangent....what psi do you guys keep your tires at?

_which_ tires? Trofeos? PS4S ?
other?

 

[Lakersfreak]

_which_ tires? Trofeos? PS4S ?
other?

Pirellis

 

[smurfslayer]

_when_ I had the Trofeos, right up through about 2 hours ago

I tried to keep them 31-33 cold PSI based on the outside temp. They aren’t supposed to see north of 38PSI hot. This is for spirited driving on the street in Texas heat.

It’s not as hot now so I’m closer to about 32psi at about 80F. that’s putting me about 30psi in the am.

I just had the --properly--shagged-- Trofeos replaced at 3700 miles. There was still a slight amount of tread left, but, the stick was GONE. I stepped on it on an interstate doing about 60mph and fishtailed like crazy in warm, dry temps. wheel spin at 60... The Coyote is good, but it’s not spin the tires at 60 good.

They stuck great for 1500-1800 street miles and then dropped off like a stone.
I just had the PS4S put on and hope for a bit longer tire life ;-)

 

[steveo1960]

I've noticed what the car says (as well as the FordPass app) is sometimes different from what is actually measured by manually checking the car. Not by a lot, but by 2lbs or so.

Me too.
About 2lbs difference.

 

[Alan Applegate]

Cold, I follow Ford's recommendation of 32 PSI. On my Ranger (I don't haul much save for my butt) I use the same 32 PSI albeit the recommended amount is 35 PSI. I'll give up a few miles of wear around town as a tradeoff for a softer ride.

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