TPMS Gremlins Got Us Good - 2014 Mini Cooper Hardtop Long-Term Road Test

Edmunds.com

TPMS Gremlins Got Us Good - 2014 Mini Cooper Hardtop Long-Term Road Test

The 2014 Mini Cooper TPMS system develops a strange error. Edmunds investigates and tries to set the system right.

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yellowbal

Stupid TPMS requirements make winter tire swap over more complicated. The TPMS fault light makes traction control non-defeatable... spinning tires is useful when driving up a snowy hill.

ebeaudoin

yellowbal said:

Stupid TPMS requirements make winter tire swap over more complicated. The TPMS fault light makes traction control non-defeatable... spinning tires is useful when driving up a snowy hill.

These TPMS systems are so finicky these days. Ugh.

seppoboy

Seems to me I recall a post in recent weeks about another vehicle's TPMS, with lots of comments that all cars should show the tire pressures for each wheel, and critics of systems that merely show a tire pressure alert. Well, here you have the complexity of a system with individual pressures, and one more infuriating thing to go wrong. Be careful what you wish for. No, I won't be impressed with comments that this or that automaker has systems and uncle's car works just fine, unlike BMW/Mini. They all have issues or the potential for issues. Mandatory TPMS may help the most slovenly car owners keep out of dire trouble due to bad pressure differentials, but at the cost of driving the rest of the population nuts with yet another ornery contraption subject to random errors and great expense.

schen72

seppoboy said:

Seems to me I recall a post in recent weeks about another vehicle's TPMS, with lots of comments that all cars should show the tire pressures for each wheel, and critics of systems that merely show a tire pressure alert. Well, here you have the complexity of a system with individual pressures, and one more infuriating thing to go wrong. Be careful what you wish for. No, I won't be impressed with comments that this or that automaker has systems and uncle's car works just fine, unlike BMW/Mini. They all have issues or the potential for issues. Mandatory TPMS may help the most slovenly car owners keep out of dire trouble due to bad pressure differentials, but at the cost of driving the rest of the population nuts with yet another ornery contraption subject to random errors and great expense.

Pretty much any electronic feature of a modern falls into this category. You should buy their Yugo. I, for one, like having TPMS -- the kind that displays exact pressure readings. I often drive with it on first thing in the morning so I can see the pressures slowly increase.

allthingshonda

If it has a reset function it must not use actual sensors in the wheels. The Mini's system must use an algorithm to calculate what the pressures are based on information from the ABS sensors. I don't know of any systems with actual sensors in the wheels that need to be driven to calculate pressures. On that first cool morning my Acura will greet me with a "Check Tire Pressure" message and warning light a few seconds after start up. And although I started getting "Check TPMS System" malfunction warnings at the end of last winter because the sensor batteries are failing I still prefer it over ABS versions.

thecardoc3

allthingshonda said:

I don't know of any systems with actual sensors in the wheels that need to be driven to calculate pressures.

Maybe not to calculate pressures, but some systems auto learn sensor ID's as well as locations and the car has to be driven for them to do so. One of the interesting things about some of those is that if the system loses a sensor (battery dies etc.) it stops updating all of them.

allthingshonda said:

On that first cool morning my Acura will greet me with a "Check Tire Pressure" message and warning light a few seconds after start up. And although I started getting "Check TPMS System" malfunction warnings at the end of last winter because the sensor batteries are failing I still prefer it over ABS versions.

That's one of the things people get wrong about tire inflation. "Cold" is the average low temperature that the tires experience which really means that tires should be checked and reset several times a year in areas with seasonal temperature changes. When inflating tires at temperatures other than "cold" you should measure the tires actual temperature, and then add 1psi to the specification for each ten degrees that the tire is warmer than the average cold temperature. For example lets use 40f as the cold temperature, and the tire's inflation is supposed to be 33 psi cold. If the tires measure 40f, then you set them right to 33psi. If the tire temperatures are 95 in the front and 70 on the left rear and 60 on the right rear the you would need to set them to approx. 38psi in the front 36psi for the left rear and 35 psi for the right rear. Then the next morning cold, they will be at the cold specification of 33.

Jonathon, there is a very likely explanation to this situation. Do you have a certified gage? Has the gage you are using been tested for accuracy? You have four TPMS sensors most likely made by Beru that are in close agreement and a gage that is some six psi higher. You need to try a certified gage and not one that scales to 160psi.

darex

I have no explanation for the phenomenon experienced here, but I do know that the MINI also measures the temperature at each wheel. I coded this function and now wheel temps are displayed alongside pressures. The amount of driving needed to reset/recalibrate the TPMS is relatively extensive, and it pauses every time the car stops (e.g. at a stop sign), then resumes.

One time last winter, on a very cold day, my TPMS warned of four equally low pressures. That only ever happened one time, so far.

With these clues to its functioning, perhaps someone can better explain what's happened here?

stever

How do you measure the tire's temp @thecardoc3?

Can't say I've noticed a pyrometer at Harbor Freight, but I haven't looked.

thecardoc3

That is something that is explained as part of an updated class on TPMS that is currently being offered for professional technicians. This is an eight hour class that has a pre-requisite requirement of both previous level training as well as hands on experience. In the class one of the routines that are studied explain how the sensors send out data bursts every 30 seconds that include how many wheel rotations have taken place in a given period of time during that thirty seconds. That information is cross-checked with wheel revolution counts based on the ABS system and then the individual wheel speeds are matched to identify the sensor locations and if necessary sensor identifications.

As far as the TPMS system alerting about low tire pressures on a very cold morning, that is exactly what the system it is supposed to be able to do, it's NOT just to alert the driver if the car is having a tire go flat. The systems are designed to alert a driver if the tires are significantly over or under inflated. A system where the specification is 30psi should turn the lamp on if the tire pressure falls below 23psi, or rises above 38psi. Shops can run into an issue when the vehicle is inside the heated shop all day when it is being serviced if the tires are set to the placard and then the car sits outside the following night. If the temperature swing is great enough, the TPMS light will come on due to the natural pressure change that will occur as described by Boyles gas law.
https://en.wikipedia.org/wiki/Boyle's_law

thecardoc3

http://www.grainger.com/category/infrared-thermometers/temperature-and-humidity-measuring/test-instruments/ecatalog/N-beo?nls=3&nlsIt=0.8&ssf=3&suggestConfigId=2

stever

$26 isn't too bad. Be better if I could stick the probe near my ear and check my own temp too. Oooh, could use it at the BBQ as well.

thecardoc3

You would be well advised to expect to spend in the $150 range to get a reliable tool with enough accuracy for this purpose. While you are there check out what a certified pressure gage runs. http://www.grainger.com/search?searchQuery=automotive tire pressure gauges&nls=3&ssf=3&nlsIt=0.8&suggestConfigId=6

stever

When I have a free five minutes, I just calibrate my cheapo gauges. (Cars Direct)

I built one of these in the backyard to facilitate the process.

thecardoc3

That might be cheaper than some of the certified gages.....