Tyre Pressure Monitoring System (TPMS)?

[Bratty]

I am VERY uninpressed with this option, It is useless! even though I had a large difference in tyre pressures between front to back Nothing!!

Dunk

[STEWY L]

i can only guess that it hadn't been zero'd correctly?
apparently it's very easy after adjusting pressures, some switch somewhere,
possibly in glovebox?
regards,
stewy.

[Bratty]

Recalibration is through the MMI but even so, my confidence in the system is ZERO. I mean I even had 18 inch wheels on the right axles and 19 inch wheels on the left (to check for clearances before having to buy another two tyres!) NOTHING. There is no check sytem to reassure you that the system is even active ie. the light on the dash (at least on my car!!?!!) never comes on even when you activate the key in the ignition (unlike ESP etc.).

Safety feature, Yes! but would not loose sleep if it was not specced on a future purchase, if you blow a 19 inch tyre at UK national speed limits you should not really be automatically visiting a mortuary as the tyre wall itself is fairly stiff and you have 19 inches of metal to run on (as long as you realise!!?!! and do not try and drive from London to Edinburgh with it;)).

Dunk

[vwcabriolet1971]

Is this system (TPMS) the full pressure monitoring system with special tyre pressure sensor valves or is the "flat tyre indicator" that works off the ABS ? I suspect its the latter and if so it does not measure tyre pressure. The "flat tyre indicator" uses the ABS system to monitor the relative speed of each wheel relative to each other. If one wheel is revolving a significant faster rotational speed than another , ( because its rolling radius is smaller) , then this is sensed as a puncture and the warning light is illuminated. In your case one wheel was not revolving faster than normal so the indicator warning light was not illuminated.
If it was the full TPMS then this would not sense any problem either as it quite normal to have high rear tyre pressures when carrying heavy loads.
I've only ever seen the full TPMS on the large VW 4x4s where the actual tyre pressure is displayed digitally on the dash display .This is a much more expensive option than the flat tyre indicator ( F.Tyre.I. was £30 on my MK6 Golf). Reports on the F.Tyre I. on the MK6 Golf section have been quite positive with advance warning of reduced pressure tyres, i.e. punctures.
If the rolling diameters of the 18" & 19" wheel were close to the 18" size ( because the 19" wheels had lower profile tyres ) then the flat tyre indicator would not be activated.

[Bratty]

Would have expected some reaction from the abs sensor TPMS as the 19 inch combo has a larger overall diameter than the 18 inch (by about 8mm on paper!), and having the two different wheels on both axles and was driven for a good few miles, would have hoped it would react:confused:.

Perhaps it is broken?

Dunk

[vwcabriolet1971]

Would have expected some reaction from the abs sensor TPMS as the 19 inch combo has a larger overall diameter than the 18 inch (by about 8mm on paper!), and having the two different wheels on both axles and was driven for a good few miles, would have hoped it would react:confused:.

Perhaps it is broken?

Dunk
May be broken but may be 8mm is at the limit of sensitivity. My MK6 Golf Flat tyre dash indicator yellow warning light does light up on ignition switch on and goes off when engine started. I suppose I'll only find out if it works is when I get a puncture.

[B8 TDI]

The best way to test it is to deflate one of the tires significantly, then drive a few miles and see if it picks it up.

[baylissboy]

It's the cheaper system, it does work off the ABS & it compares the wheel speed & it takes quite a few miles to register. The better system is the valves with the built in sensors that transmit the tyre pressures to a control unit, as fitted to RS4, RS6 & A8.

[Zenerdiode]

I've got the ABS TPMS on my A4 - and I admit it works very well. I have a very slow puncture in the left front and every three weeks or so it tells me. Normal pressures for the 19" wheels are 36psi front and 35psi rear. It is alarming when the front left is dropping to 32psi. I think that is very good resolution.

It works by comparing the angular velocity of each wheel to each other and the benchmark stored when you store the 'pressures' via the MMI. It uses many other factors too, such as steering wheel angle (turning right for example, the left front wheel turns more than the right rear with the others somewhere in between - it has to take this into account) and a 'rough ride' signal generated by the ECM.

[satsu]

I think it says it all that somewhere along the line Audi decided to rename the feature "Tyre pressure loss indicator" along with the following disclaimer-loaded description: "A visual and acoustic warning when the system detects a potential loss of tyre pressure".

When I first got the car I pumped up the tyres and reset the TPMS. I didn't check them for a couple of weeks because I assumed that the system would tell me if there was a significant drop. Unfortunately when I did check one of the rears had actually gone down from 36 to 28 without it telling me. Not a catastrophic loss of pressure, but enough to result in some nasty wear on the outside of the tread if I hadn't caught it.

Looks like Zenerdiode has had a better experience, but I certainly wouldn't rely on the system and I would put the £75 towards something else if I buy another one.

Steve

[vwcabriolet1971]

I think it says it all that somewhere along the line Audi decided to rename the feature "Tyre pressure loss indicator" along with the following disclaimer-loaded description: "A visual and acoustic warning when the system detects a potential loss of tyre pressure".

When I first got the car I pumped up the tyres and reset the TPMS. I didn't check them for a couple of weeks because I assumed that the system would tell me if there was a significant drop. Unfortunately when I did check one of the rears had actually gone down from 36 to 28 without it telling me. Not a catastrophic loss of pressure, but enough to result in some nasty wear on the outside of the tread if I hadn't caught it.

Looks like Zenerdiode has had a better experience, but I certainly wouldn't rely on the system and I would put the £75 towards something else if I buy another one.

Steve
VAG did appear to get their knickers in a twist when describing the TPMS ABS system in the various model brochures , as having pressure sensors. My MK6 Golf ( with flat tyre indicator ) service details in the car manual , informs me that the tyre pressure valves in each wheel should be replaced every 6 years. The only problem being, is that the car doesn't have any ! and they were never an option in the UK.

[Borab0y]

It's the cheaper system, it does work off the ABS & it compares the wheel speed & it takes quite a few miles to register. The better system is the valves with the built in sensors that transmit the tyre pressures to a control unit, as fitted to RS4, RS6 & A8.



It seems to be a common mis-conception that for a direct system, the sensors are built in the valve, they are seperate and bolt onto the valve.

Each part can be changed seperately but it is recommended that if the valve is removed from the rim it is replaced.

[baylissboy]

It seems to be a common mis-conception that for a direct system, the sensors are built in the valve, they are seperate and bolt onto the valve.

Each part can be changed seperately but it is recommended that if the valve is removed from the rim it is replaced.I know that the items are separate, but you try to split them when they've been on the car for a couple of years, they may as well be one part!!!

[Borab0y]

Baylissboy, the comment wasn't aimed souly at you, like I said, its seems to be a common idea. I see people writing it all the time.

[SunnyBard]

It's the cheaper system, it does work off the ABS & it compares the wheel speed & it takes quite a few miles to register. The better system is the valves with the built in sensors that transmit the tyre pressures to a control unit, as fitted to RS4, RS6 & A8.

I decided to save the cost of the TPMS when speccing my options. I've seen some references to enabling and disabling it with VAG-COM, is this purely a software option, or does it need any hardware mods too?

[vwcabriolet1971]

It has the set /re-set switch.

[B8 TDI]

It has the set /re-set switch.

The B8's do not have a set/reset switch the radio//mmi interface is used to set the system. and yes it can be done with only a VAG Code depending on your control unit.

[SunnyBard]

I gather the set/reset functionality can be enabled in MMI too, but I didn't spec that either (spend my options pennies on mechanical bits more than computer bits).

[SunnyBard]

the radio/mmi interface is used to set the system

So even without MMI it's possible? I'll see what ABS unit mine gets delivered with ...

[B8 TDI]

Correct, http://www.audienthusiasts.com/VagComABS.html