Thread: EAS behaving erratically- please help

Oh and I plugged in my RSW software when I got hme, no faults and no faults flashed up at any point in the day....

sounds like you have internal leaks. inside the valve block (high pressure air is getting to places it should not, wrong valve in right hole or leaking valve galleries). there is a small possibility that you have the two rear bag hoses swapped, but this normally makes the car lean to one side unless the compressor cannot put out enough pressure. in which case one side goes up and down slowly.

This all occurred at my place this afternoon. I have never seen a P38 behave like this.

It was automatically lowering itself from any manually selected height (inhibit switch on) and then raising itself again virtually straight away. It seemed to only drop one level from what ever was selected but every now and then drop two levels. The raising process (rear first each time) was generally slow as if no pressure in the tank. The same behavior happened with the inhibit switch off. But then it seemed to move up and down over all levels more randomly.

Originally Posted by Rupert Prior

there is a small possibility that you have the two rear bag hoses swapped

Some pipes the wrong way round was one of the possibilities I thought of while watching it "dancing" too. It just looked confused?!? If that makes any sense...

If one of the small inner solenoid O rings dropped off (with out being noticed) when putting it back in would that create "high pressure air going where it's not meant to"?

Would a knackered height sensor force the hunting effect of it dancing up and down? At what point would that hunting/dancing create a fault?

I also thought the EAS driver could be shot just simply because something kept forcing the thing to lower off a selected and inhibited height. Any more ideas?

UK-P38, I am gonna get my spare valve block back tomorrow and rebuild it so we can swap it over and open yours up. Will give you a call tomorrow.

Couple of things: Have good look at the EAS Driver block mounted on the Valve block beside the compressor. It is resin sealed. If the resin is highly discoloured and flakey it's a reasonable bet that the Driver is shot from heat shock and needs replacing. It will play all sorts of tricks when it's not working as it should.
Have a look at the height sensors with an analogue multimeter. As the sensor is opened and closed smoothly, the change in resistance reading should likewise cause the needle to swing evenly. If it jerks around, then there's a problem with the tracks. Inside the circular "elbow" of the sensor, there are three 'fingers' which press on three parallel copper tracks thereby making contact. The tracks become worn.

If there is a problem with the tracks, swap the sensors L<->R (if this has not been done previously) and they will behave essentially like new. The sensors are not "handed" so can be fitted to either side of the vehicle. Let's say there's about 270 deg of movement in total, but only about 60 deg is used between access/high settings. Thus when "inverted" to fit the other side of the vehicle the hitherto unused section of track is pressed into service.

Assuming all valves are operating as they should, the front end 'dancing' points to a faulty sensor and/or a dodgy EAS Driver block...it could be both.
Let's know what happens?
cheers

Cheers guys, after some more searching it does sound like it could be either the drive block or height sensor. Possibly lowering the car this time was the one to push the sensor over... The thing I find strange is that it just started happening after only really minor work to the valve block. Didn't even remove it and didn't touch the solenoids on the underside, so cannot see how air can all of sudden be leaking to the rear left...

Will try swapping the rear sensors over. Going to look at the software readings as the rear left goes up and down at lunchtime...

DT-P38, does your other block have the driver too? Will be pretty simple to plug another one in?

Maybe it's just wants to Rock around the Christmas Tree!

Originally Posted by UK_P38

DT-P38, does your other block have the driver too? Will be pretty simple to plug another one in?

No but I know where we can source one relatively easily.

I just checked the height sensor height readouts on the RSW software as the car danced around and they seemed to correspond with the wheel positions suggesting the sensors are fine. I think I will swap them to be sure when i get the chance. During testing it started searching with less extremes in height but at other times it went back to the original big movements. I did try playing with the wires coming out of the 'black box' that gets pulled out to shut off the EAS controller but could not find a correlation between doing this and the 'searching' getting better or worse (it never actually stopped searching and was settled). Could damage to these connections cause the problem, maybe the wires were yanked when the box was removed, I'll remove the plastic covers to get a better look...

It seems to be doing the following cycle, maybe...
Pump up tank to 140psi, let up rear left higher than it should be, refill tank to 140psi and let the rear down beyond level, then repeat. The amount of up/down seems to vary.

Thoughts now go to the driver, obviously, with all the pumping, it gets pretty hot in there. I guess the only test is swap it out?
When the engine is shut down it seems to go through a lot of levelling process also, probably related...

Certainly getting familiar with the system! Anyone else had anything similar?

UK_P38

I'm guessing here that you have an EAS bypass with a guage for measuring the tank pressure? Hence, you know that you are getting up to 140 psi in the reservoir. Working on this assumption can you remove the "black box" relay from under the passenger seat to disable the EAS system then manually inflate the left rear with a compresser. Once this is done does the bag deflate immediately? If yes I would look at potentially a valve stuck wide open, if no then I would start looking more at electrical parts such as the sensor or EAS driver block.

Good luck

Gary