Tyre pressure monitoring

[satsu]

Checked my tyres last night. Most of them were where they should be but one of them had dropped from 36 to 33. I was a little disappointed that the tyre pressure monitor hadn't told me about this 10% drop.

So, my question is what sensitivity should I expect from the system? How far does the tyre pressure have to drop for it to tell me?

I was already a bit miffed when I discovered (just after ordering :mad:) that it didn't actually monitor your pressures, just the wheel circumference. It now seems that basically all it does is tell me if I have a flat.

[rd1]

Hi,
thats not so good as the whole point is to tell you when maintenance is needed before it becomes a problem.
I had assummed that once the original pressures were recorded via the MMI it would indicate any drop from that pressure but from what you say perhaps not??
Must admit my previous car (Peugeot 407)had the monitors and they were superb giving two warnings, one for a slow reduction in pressure and the other for a puncture with graphics etc.
Thats what made me go for the option on the A4, although I have yet to see it operate (hope that it never does of course!!)
Interesting to see others experience of it operating
Roger

[jakerade]

yes that is my understanding as well - it just tells you if its going/gone flat - i was looking forward to a nice display showing 4 wheels and their pressures

[Plife]

Great dissapointment this! Luckily I found out how rubbish it was so didn't bother to get it.

[Airgun]

I don't think it's useless, the system warned me when I had a puncture (the tyre still looked inflated).

It could save a nasty high speed blowout - not bad for the cost.

I think the tyre pressure monitoring could be turned on for free using Vag Com.

[rd1]

Airgun,
perghaps not a waste of money, you have made me feel better :D.
Does it give low tyre pressure warning and identify the tyre or just give a straight puncture graphic for one of the wheels?
Roger

[Airgun]

RD1, when I had the puncture it told me to check the pressure in the specific wheel.

I think for the cost everyone should go for it, I check my tyres at least once a week but puntures can happen, I would rather have bit of warning before a completely flat tyre at 80MPH!

[rd1]

Thanks Airgun,
your description is what I expected for the £45? option so I am happy with what I have got.
Roger

[Dans]

I think this feature is especially of benefit in countries where winter and summer tyres are used. Twice a year we change tyres and when this is done the idea is to reset the tyre pressure gauge to suit the new tyres. Perhaps in the UK where I don't remember there being winter or summer tyres, rather just tyres, this feature has less going for it.

[jon_iz]

Does anyone know if the TPMS can be added from "flicking the right switch" in VAGCOM?

[ScottyUK]

This system uses sensors that are in/replace the value stems. There's also a receiver so flicking a code on what really help.

I'm wondering what happens if you need a new tyre or a puncture fixed as normally you get new valves.

Anyone know? :confused:

[jon_iz]

This is the case for other cars (I know Peugeots and Renaults use this method) however, not for the B8.
According to the users handbook, the B8 uses the ABS sensors to measure the rolling circumference of the tyres. It compares the rotation of the all wheels and if one or two wheels start to give different rotational speed to the others, it will flag it as drop in pressure (e.g lower pressure = reduced diameter = more rotations than other wheels). This would need to be averaged, to account for cornering.
Therefore, as all the hardware already exists for the ABS and ESP, it should only be a software switch to enable the feature...
I also assume that if all the tyres dropped by an equal amount, it may not register, unless there is significant vibration...
The system on the B8 is not capable of giving a true pressure reading, as far as I am aware.

[Airgun]

Does anyone know if the TPMS can be added from "flicking the right switch" in VAGCOM?

I think so, my car has the TPMS from the factory - when I mess with Vag Com it show the option with a tick in it.

I think on other Audi models you could retro fit TPMS by fitting a switch (with new wiring) and turning it on with Vag Com, as on the new A4 you store new pressures with the radio it should just be a software change.

[ScottyUK]

This is the case for other cars (I know Peugeots and Renaults use this method) however, not for the B8.
According to the users handbook, the B8 uses the ABS sensors to measure the rolling circumference of the tyres. It compares the rotation of the all wheels and if one or two wheels start to give different rotational speed to the others, it will flag it as drop in pressure (e.g lower pressure = reduced diameter = more rotations than other wheels). This would need to be averaged, to account for cornering.
Therefore, as all the hardware already exists for the ABS and ESP, it should only be a software switch to enable the feature...
I also assume that if all the tyres dropped by an equal amount, it may not register, unless there is significant vibration...
The system on the B8 is not capable of giving a true pressure reading, as far as I am aware.

That's good to know. I read that this system wasn't ready for the B8 in time for launch. Obviously this was out of date info.

Glad to be corrected :beerchug:

[A1exp]

I've got TPMS and it doesn't seem to work well at all.

I was hoping it would flag up when my tyre pressure dropped slightly so I could top up, but my wheels can lose quite a few PSI gradually and the monitor stays silent.

Not tried to let a load of air out to test as I don't fancy pumping the tyre up by hand again...

[Tolmie18]

I think the tyre pressure monitoring could be turned on for free using Vag Com.[/quote]

Anyone else know if this can be done??

[mghassey]

Currently my TPMS isn't working at all for some reason but it has been of great assistance previously when I had a slow puncture in one tyre. What I found was that every time the system indicated a problem I had lost 2psi in that tyre over about a week. One thing to watch though is that the system seems to work from the traction control, (some say the ABS ??) and when one wheel starts behaving differently it shows the alarm. As I said above I had a consistent alarm every time ONE tyre lost 2psi. However, I checked manually once before a longish trip and found that ALL 4 wheels were over 2psi down from previous which of course gave a consistent traction control on all 4 wheels with no error showing, (yes, I'm too lazy and relied on the TPMS too much!).
Currently it isn't working at all though, I had a complete flat & couldn't stop immediately as it was on a roundabout and no error was given while I hobbled to safe spot, shredding the tyre completely in the process of course. After replacing the tyre I tested by inflating & deflating and couldn't get it to show a fault, so any ideas on that greatly appreciated!

[ScottyUK]

When they were all the correct pressures did you set that in the MMI? It needs that to get a it's baseline.

To test it you'd have to drop the pressure and drive for a while. Not sure I'd want to do the risk to the tyre and rim.

I'm not sure of the best way to test it other than plug in VCDS and look for errors.

[mghassey]

Hi Scotty, yes I did reset the pressures in the MMI both before I had the blow out that first alerted me to the problem, mind you I did have a bit more on my mind at the time! And also after having the new tyres fitted I reset it again and as usual the fitters had grossly over inflated and so I after I got home I dropped one of them back to where it should be & drove for a while but still no warning light. I have had the warning light consistently after a slow puncture dropped the pressures by 2psi until I got it repaired so I'm sure it should have come on. It's in for service in the New Year so I'll get them to look at it as well, but if it comes as a typical Audi repair cost I'll just live without this "nice to have". It does make me more than a bit lazy physically checking them I'm afraid! Basically it's only a software switch in the control unit so unless something drastic has happened there I don't really understand what's going on.

[ScottyUK]

Just had four new tyres and my fitters under inflated!! LOL

Afraid ive not got a clue then other than plug it up for a diag test.

[mghassey]

I'll post on here as and when I get a definitive answer Scotty, may help somebody in the future.

[JimA4B6]

Guys this is my line of work, you'll find that what you have isn't really TPMS it's a software add on which uses the ABS ring to check every tyre revolves as it should so there is no actual 'pressure' sensor. This style is called indirect as opposed to direct which have actual sensors inside the wheel. Indirect systems are slow and unreliable but also the cheapest option for manufacturers. You can buy aftermarket TPMS kits and use these instead, all be it not on the MMI.

[ScottyUK]

Yep - that's why many have enabled it for free just by changing a code with VCDS on the ABS control module.