SQLGuy

This is my second GTS. The first one had a lot less miles than this one, but on neither one did the tire pressure warning system work what I would call correctly. Basically, they start warning of "Tire pressure loss" when the cold pressure drops below about 40PSI. The manual, however, calls for 36PSI.

Is there are any calibration or modification work (besides disabling the system entirely), that will allow me to run correct pressure without the warnings?

pcar928fan

I have seen them work... My '92's worked at first. I think they are really quite accurate and most of the time it is poor tire pressure gauges not reading right that makes you THINK you have 40psi, when actually it is probably just 37 or so. That said, when a sensor goes out it is BIG MONEY! If you can even find them. I would commonly just run ~40psi in my '92 so it would not fault, but now I do have a sensor that is dead, so I am always getting a fault on one wheel.

I agree that they should have set them up to fault at something like 32psi instead of 36+ because then it is always faulting and becomes the boy who cried wolf... Very frustrating. That is (at least in part) why they were dropped in '94!

Vilhuer

All what can be done is in owners manual. Even if system works perfectly its practically useless since its threshold value cannot be set. Modern rubber require and work best in different pressure than original factory minimum value.

RKD in OKC

The RDK worked great on my 90GT. It saved me from coming out to a flat tire from nails twice by warning me the pressure was low. However, it only worked when I set the system according to the manual ie., Air the tires up to the low pressure, drive around the block, add air to high pressure, drive around block, then bleed down to set pressure. Any other method including using the Hammer and they would false within a few days or when the ambient temps changed.

oaros

Yep it does. Reminded me to fill up my leaking tires every couple of weeks.
Real world usefulness - not much; a working hatch release is worth more. New wheels make it useless.

Good for feeling smug for 10 secs when you meet another 928 owner who can't get his to work. ;-)

Podguy

A while back I was trying to sell two 90 S4 rear wheels with four sensors and had no takers. This makes me suspect no one is really using the system on late model cars. I have seen one system in a 90 that worked properly.

cold_beer839

The RDK worked in my GTS without issues. I think it works by comparing tire pressures on the same axle. If the pressure between those 2 opposite tires varies much, it sets off the warning. I switched to 18" Carrera III's and had to disable the system.

WallyP

I think that the system simply monitors the wheel sensors, which are off/on switches operated by air pressure. When the air pressure drops below the setting for any switch, the RDK warning is set.

Vilhuer

Exactly and when one of two sensors in one wheel is off and another is on fault is given for sensors in that wheel. System knows speed of the wheel from same corner ABS sensor and can monitor when it reads 1st and 2nd wheel sensor. It can't say which one is faulty but knows one has to be if both sensor inputs are not same.

Podguy

So the dual sensors on the wheel are simply for redunancy? At $450 a sensor this sounds like an expensive way to get a back up system.

Podguy

Oh I forgot. Does any one make plugs to replace the sensors so the wheels can be used on cars with out the system. I remember looking at wheels at DEVEK with all the sensors removed and the holes left with wheels stacked in piles.

Vilhuer

Factory saw it as critical setup. They did not want falce alarms. In reality it was too much too early. 20 years later similar systems work much better.

Only plugs I have seen were made by TechArt. They sold off old stuff some time ago in German eBay and had few extra plugs available. Friend has them now.

Back in early nineties TechArt sold special OZ Mito-3 18" wheels which had holes cut for sensors. For some reason they saw need to do plugs for them also. AFAIK those wheels are only aftermatket and 18" RDK wheel type in existence.

ROG100

Worked perfectly on my GTS for the first 6 years of my ownership - then I changed the wheels. I really miss the system and its accuracy. Read the manual and it is very easy to use - any issues are mostly operator error.