GolfGTIforum.co.uk
Model specific boards => Golf mk5 => Topic started by: funkythumbs42 on 10 January 2010, 10:23
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As per below
(http://i28.photobucket.com/albums/c243/gregorilla/set.jpg)
What does it do excatly? :grin:
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It’s to do with the tyre pressure sensor. Don’t take this as 100% but when you change your tyres, or after one has gone flat and you pump it up, you press it to set it to that tyre pressure. Then if a tyre goes below that pressure it warns you via the instrument dial.
There should be something about it in your owner’s manual.
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^^ What he said. Hold it down to calibrate the system to your tyre pressure.
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Yep. Basically hold it down until it beeps everytime you pump your tyres up (or have new tyres).
I have to say that it's near useless, as it seems unable to detect sever drops in tyre pressure until it's too late.
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No its not useless at all , I rate it very much. This last month I have had 2 screws in a tyre, one of which had I not stopped streaght away, would have gone right through. I managed to pull it out before it went through the tyre!! Saved me buying a tyre becuse it was right on the end. The other tyre at the front had a punture, the set button told me imadietly!! :wink:
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How?
You must have been losing pressure for the sensor to activate the system?
I let my 2 front tyres down on wednesday to gain a bit of grip in the snow. I did it when the car was turned off and locked up mind. But the system never reminded me the tyre pressures had been reduced???
Sam
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There is no tyre pressure sensor. Just something that measures the rolling radius of each wheel and warms when there's a drop in the rolling radius. Problem is that you need a significant enough drop in pressure before the system detects it. I've lost around 10psi before the warning comes on.
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Yep I know exactly how it works, but still having a screw in the tyre but not enough to reduce the pressure is not going to reduce the rolling radius?
Saying that low profile tyre dont help as the side wall is a lot stiffer
Sam
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Hi Sambo, Last Sunday I had a screw in my tyre and the ping went off on the dash. I stopped right away noticed a screw had gone in the tyre. Got the punture fixed 15 quid. Its as simple as that its never let me down before!! Brilliant little gadget IMO thanks Steve :wink:
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I managed to just catch a ratchet strap on the motorway. The hook caught the inside of the tyre. I thought that it was ok as the steering felt fine. But as I came off at the next junction the warning light came on. I pulled over, hopped out and watched the tyre go flat. Shame it doesn't tell you which tyre it is though.
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Hi Sambo, Last Sunday I had a screw in my tyre and the ping went off on the dash. I stopped right away noticed a screw had gone in the tyre. Got the punture fixed 15 quid. Its as simple as that its never let me down before!! Brilliant little gadget IMO thanks Steve :wink:
Hi Steve, sorry I didn't understand what you mean't in the previous post. What you are saying is that if you had driven around on it for much longer it would have goosed the tyre completly meaning a replacement tyre?
Do you have to cover a few miles before it goes off, or maybe just be travelling at the time? Like I say mine didn't recognise my tyres were at 26 psi when I let them down and there was a noticable differance visually which I would have presumed would have have affected the rolling radius. That being said I only drove a mile or 2 after to the nearest garage and pumped them back up to 31 psi. Will increase them to 35 psi once the snow has gone completely.
Sam
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Yes Sam . the first screw that went in I got it just in time before it went through the tyre!! I put a bit of washing up liquid over it to check if there was any air comimng out (none) It must tell you when there is a nail or screw in there? I'm on my 5th mk5GTI and its never let me down yet!! Hope ive explaned it a bit better steve30 :huh: :wink:
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Like I say mine didn't recognise my tyres were at 26 psi when I let them down and there was a noticable differance visually which I would have presumed would have have affected the rolling radius.
It uses the ABS sensors to detect a difference in wheels speed across each axle. If you'd kept one front tyre at 35psi and dropped the other to 26, it would have warned you.
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they are very useful IMO. Saved me a couple of months back on the m6. It went off with me 20 miles from home, i presumed it was an error so reset it. A few mins later it went off again. As i was nearing a junction i came off, once pulled over there was a huge screw the size of a pound coin sat in my tyre with the air rushing out very quickly. I hate to think what would have happened had i tried to get home at motorway speeds, I'd imagine a lot more hassle than a new tyre!!
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I was told that they are sensors inside the wheels and not of the type that use the speed of each wheel to determine if the tyre is flat or not. Which is correct?? :undecided:
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Mine goes off with as little pressure drop as 2 or 3 psi.. bloody annoying! Must have something to do with the type of tyre.
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I was told that they are sensors inside the wheels and not of the type that use the speed of each wheel to determine if the tyre is flat or not. Which is correct?? :undecided:
Its definately the el cheapo ABS system and not the sensor in the tyre version.
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Like I say mine didn't recognise my tyres were at 26 psi when I let them down and there was a noticable differance visually which I would have presumed would have have affected the rolling radius.
It uses the ABS sensors to detect a difference in wheels speed across each axle. If you'd kept one front tyre at 35psi and dropped the other to 26, it would have warned you.
Is that really the case or was it that he had the ignition off when he let the pressure in the tyres down. I thought it might only detect a change in rolling radius whilst the system is active i.e. when the ignition is on?
I don't know the answer btw, just intersted in how it works.
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Like I say mine didn't recognise my tyres were at 26 psi when I let them down and there was a noticable differance visually which I would have presumed would have have affected the rolling radius.
It uses the ABS sensors to detect a difference in wheels speed across each axle. If you'd kept one front tyre at 35psi and dropped the other to 26, it would have warned you.
Is that really the case or was it that he had the ignition off when he let the pressure in the tyres down. I thought it might only detect a change in rolling radius whilst the system is active i.e. when the ignition is on?
I don't know the answer btw, just intersted in how it works.
I'm pretty sure that if you deflate a tyre with the igntion switched off, it'll pick it up when you start rolling unless you've pressed the 'set' button. Have to admit though, I've never tried that!
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Just to add seeingt as this thread had come up again. I let both out by hand so when I pumped them back up again one was at 26 psi the other was 23psi.
I'm pretty sure it will only detect a dropping rolling radius whilst it is being monitored (ie when the ignition is on) this is why people are saying it doesn't work very well I think. If you have a slow puncture and do many short journeys it probably doesn't register such a small drop on every trip as a fault . That seems to make sense to me anyway, looks like it can be quite a good system if you get a puncture on a long journey according to other peoples experiances, but then kind of defeats the object of having the set button in the first place?
:huh:
Sam
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I had a slow puncture when I first got my car and it only seemed to register a pressure drop on longer journeys i.e. over 10 miles.
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It monitors it constantly when you are moving because it compares against the other wheel on the other side of the car. I believe it's like that to allow you to set your front tyres lower than the rears in winter/snowy conditions. I assume it has some sort of allowance delay for the tyres warming up which will increase the pressures so it may not notice straight away if you only do very short journeys.
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Makes sense but then the question 'why bother setting the tyre pressure with the button' arises. Surely it could conduct the same monitoring just by comparing the rolling radius from turning the ignition on? Ideally if you came out in the morning to find out some one had let your tyre down a bit, you'd want it to tell you (if you hadn't already noticed by the way it drives) but this system won't do that :undecided:
Sam
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rolling radius :lipsrsealed: :grin:
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:tongue: You know what I mean :grin:
don't you? :huh:
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the wheels need to be moving for the abs sensors to detect anything - i think in the states they actually got pressure monitors in the wheels on some models of mk5
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yep sure so why doesn't the car automatically log the rolling radius at the beginnning of every journey and if it detects a drop within that time, throw up a warning. Therefore completely eliminating the need to set a particular tyre pressure?
The set button appears to be useless :huh:
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not really sure what you're asking, and i'm crap at explaining stuff :grin: It can't measure differences until the car is moving and the tyres are up to temperature - it may even have to reach a certain speed for a certain length of time, not really sure. It will then compare front n/s against front o/s and rear n/s against rear o/s. If there is a discrepancy with either it puts the light on. You can press the reset button without inflating the tyre but in a few miles it'll notice that there is a discrepancy again and put the light on until you get the tyre pressures matching, either front or rear and then reset the system again. I think the steering angle sensor even plays a part in the process.
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Sambo, what you are supposed to do is inflate all your tyres to the correct (or your choice) of pressure then use the set button. Now, don't touch the set button again until next time you check/inflate/replace your tyres. Pressing the set button provides a datum for the system to work from.
The system is for detecting a flat tyre, rather than monitoring tyre pressure. It's looking for bigger changes than just a few psi.