Tyre pressure warming system

[haelewyn]

Does anybody have an idea how fast one can expect a warning from the tpws in case of loss of air in one tyre ?

Was having the warning during the night. Stopped at a gas station where I was able to use an automated inflation machine..    no idea how low my pressure went but the machine took a long time on one front tyre to bring it to level.

Checked today around 3 pm and no air was lost so it doesnt seem to be a puncture.

The compressor that is in the back of the car is quite ok for the job, I must say. With a good and readable scale.

Need to have 2,6 on front tyres and 2,4 on the back ones, by the way.

I should have checked my tyre pressure before but was kind of guessing the electronics would warn me if something is wrong.

I remember in the renault the warning already came when losing 10 percent of pressure or sooner. Seems this system with no individual sensors per wheel is more slow (???).

[Cyker]

It's very variable for passive systems - The active systems will always be faster as they have solid pressure data to work with.

The passive systems essentially 'guess' - They depend on the wheel being so deflated that it's physically smaller than the others, and has to turn slightly more for the same distance.

Because of this, the system can't really detect punctures if you're turning, only if you're driving in a straight line, and for long enough for it to notice one wheel is turning slightly more than the others outside a margin for error.

The passive systems tend to be of very limited use in an urban environment, and often only notice punctures when it's already very obvious by sight that the tyre is low. They work a bit better on e.g. the motorway since they tend to have long straight runs.

 

[haelewyn]

I'll try to drive in a straight line even more than I did before now. 😀

I am still happy that toyota didn't install individual sensors per wheel cause of the cost to replace or the fact that they stop working after x years.

Didn't know the passive systems were this slow .... I know now then 😀

Logically, with low profile tires like the 18" I have, it will take especially long to notice a tire running flat (?).

Must check in advance more often again.

[Cyker]

Yeah, the passive system is definitely not a replacement for regular manual checks! And as you say, the effectiveness is diminished the lower the tyre profile.

I must admit, although I was leery of the active system, it is very convenient and I rarely check the pressures manually now as I can see them all for each wheel in real-time while I'm driving. As you say, will be expensive when they need replacing later (Albeit ~10 years time, but for the convenience it'll give over that period I don't begrudge the cost. And hopefully they'll be cheaper by then...!)

I must admit the hybrid is making me lazy with my regular car checks; Compared to the Mk2, which I was checking every week at one point because it was using so much oil, none of the fluids drop and the TPMS means I don't even need to check the pressures regularly. In fact, the only thing I do have to top up regularly is the thimble-sized windscreen washer bottle!  

[haelewyn]

Read from some guys that in case of a flat tyre, the system is not able to warn the driver in time..

Sensors get crushed (active) in the wheel or the sensor reports to it's receiver about once every 15 minutes...  which means the tyre can run flat faster than the system can detect it.

I used to check oil and fluids + tyre pressure very often but it seems I started to trust on the electronics a bit too much. Car has 4000 miles so I am expecting it to not consume any oil at all now... think I must have checked the oil about 5 times by now.

Tyres got more difficult. Every petrol station used to have a thing to measure the pressure but that is not the case any more where I live.

[FROSTYBALLS]

1 hour ago, Cyker said:

It's very variable for passive systems

The Aygo used an indirect or passive TPMS, whereas the Aygo X uses a direct or active TMPS (same as the Yaris, etc).

Tyre pressure warning light: What is it? - Toyota UK Magazine

[haelewyn]

According to my manual, mine (aygo X) is a passive system. Describing it works by controlling the speed of the wheel / done by the abs system.

It needs resetting. It doesn't show individual tyre pressures..

Wheel 'plugs' looks like passive system too.

[FROSTYBALLS]

Passive (indirect) systems use the ABS speed sensors to detect differences in tyre rotation and whether there is a loss of pressure. Active (direct) systems use pressure sensors in each wheel.

[haelewyn]

That's why all points to a passive system in my aygoX in my humble opinion...

But like with everything,  I wouldn't bet my life on it.

Just saw my autocorrect made a f* up in the title... not warming but warning system.🙃

[Cyker]

7 minutes ago, haelewyn said:

Read from some guys that in case of a flat tyre, the system is not able to warn the driver in time..

Sensors get crushed (active) in the wheel or the sensor reports to it's receiver about once every 15 minutes...  which means the tyre can run flat faster than the system can detect it.

TBH I suspect those are myths made up by haters; There's no way the sensors could be crushed unless the rim itself was crushed, as it sits flush against the sidewall of the rim next to the air valve, not on the face - The rim would need to have buckled at that point for the sensor to be impacted, and in such a case you'd probably be more concerned about other things!!   

I'm not sure that the update period of the system is, but it's definitely a lot less than 15 minutes, at least in the Mk4. I suspect it's some number of turns of the wheel as it seems to update more frequently when I'm hauling down the motorway than in town, but then again that might just be because the pressures don't change much at urban speeds, but do at higher speeds. (It's surprising how much higher they'll go when I'm hooning around!  )

 

15 minutes ago, haelewyn said:

I used to check oil and fluids + tyre pressure very often but it seems I started to trust on the electronics a bit too much. Car has 4000 miles so I am expecting it to not consume any oil at all now... think I must have checked the oil about 5 times by now.

Tyres got more difficult. Every petrol station used to have a thing to measure the pressure but that is not the case any more where I live.

Same! Who would have thought there's a downside to reliability!  

It's hard to feel more motivated to check all the levels when they never move  

The petrol stations here have air pumps but they're not free, so checking the tyres would cost me like 50p or something ludicrous for 2 minutes of air; I'd rather just use my battered old foot pump (Which seems consistently read 2psi high over the TPMS sensors, but as it's consistent I can compensate for it!)

I'm sometimes tempted to get one of those fancy dial gauges that only read pressures (And can release some air if it's too high) but really it'd be just another thing for me to loose  

 

 

7 minutes ago, FROSTYBALLS said:

The Aygo used an indirect or passive TPMS, whereas the Aygo X uses a direct or active TMPS (same as the Yaris, etc).

haelewyn's not in the UK so I suspect they may not have the same specs as the UK Aygoxes.

 

[zuh]

Hi,

My Aygo X is 6 months old and about 2000 miles.

Last week, the TPWS lit. I did not find any nail and the tyres looked fine. I went to the inflator. The pression read 2,4 instead of 2,6. I inflated 4 tyres to 2,6 and I reset the TPWS.

This would mean that I lost 0,2 bar in 6 months, which is possible.

My conclusion is:
- Either the TPWS was initially set with a pressure higher than 2,6 bar. Maybe the factory inflates more so that the car does not lose pressure if it is stored for some time?
- Or the Aygo TPWS is VERY sensitive. It seems to me that the regulation demands warning a loss of pressure of 20%. Maybe Toyota set it to 10%. This would be no surprise given all the safety devices in the car.

[haelewyn]

This is a copy from the aygo x's manual that makes me think the system is passive :

"" Your vehicle is equipped with a tire pressure warning system.

While the vehicle is in drive, the system monitors the fluctuations in the wheel speed signals that are output by the speed sensor for the brake control system.""

I don't (really not)want to be a wise ***** guys.

[Cyker]

I think it's pretty safe to say you have a passive system, esp. if you have rubber air stalks - All the euro-spec TPMS have hard aluminium stalks.

The Toyota head office for each country gets to choose the specs so not that surprising they're not all the same.

 

[Squishi]

Just to be sure, because i don't have the car yet but looking for rims and stuff.

Aygo X just shows the sign on the left, which is indirect (so no need to buy sensors), correct?
Picture on the right shows active system with pressure for each wheel and temperature

[haelewyn]

On aygo x there is no image like the one you showed with tyre pressure per wheel. Not on mine anyway.

Only in the menu a way to reset the system which takes pushing of the "ok" button for quite some seconds.

Imho, backed by the manual of the car, the system is passive on my car.

Will look at the valves this weekend if I don't forget... but if I remember right they are the wobbly rubbery kind (passive).