EAS How is it supposed to work?

I am sick and tired of my EAS drooping down one side. I have replaced the air spring and it's still no better. I can't find any leaks, and i get no errors.

I want to spend time going through the whole system to check it.

Firstly though I need to know how it is supposed to work before I look to see what it IS doing before I can figure out why it's NOT doing what it should be.

As far as I am aware it is just a simple closed loop system. It checks the height sensor for each wheel, compares that against the height setting, if it's too low it puts air in the air spring, if it's too low it lets some out.

Does it do this to all corners at once or does it do it one axle at a time.

What happens if a height sensor gives a new reading, how quickly should the EAS respond? is there another sensor that detects how level the body is?

I presumed that the compressor on/off duty cycle is just controlled by a simple pressure sensor and is not controlled by the EAS. Or does the EAS read the system pressure and then control the compressor?

Is there anywhere that tells you all this in detail?

What I want to do is connect up some LED's to each of the valves in the valve block and the compressor and bring them into the car so I can see what is switching or not and when.

If the car is only dropping at one corner and you have replaced that air bag with a new one then it must be an air lleak at the connection or in that lair ine. Checking with soapy water is not fool proof. Sometimes the rubber in a bag or line moves slightly and effects a temporary seal with itself.

If it's the entire side of the car then could be the other air bag or air pipe. Possibly a valve block but I don't know about that at this stage. My money is still on a hose or a bag.

Think you are looking too deep for a simple air leak though. Good luck.

I wanted to understand the logic in the system to help diagnose the problem.

From the little I know of the system and the symptoms it is displaying, I cannot see how this can be a simple leak.

It doesn't always droop, but it is always the front drivers side when it does. Some times it comes up as soon as the engine starts. other times I have to drive a mile before it comes up.

I will try to follow the pipe from the wheel to the valve block and see what I can find.


When the car is parked, in a perfectly working EAS system (if there is one) should the car stay at the height it was last in, or is it normal to lower?

Have you had a read through these forums mudflap ?
RangeRovers.net :: Index

Have a look at the link Kenny posted to start with, theres tonnes of info over on that site about the EAS system.

To try and roughly answer some of your questions though...

You have replaced just one air spring, why?? Was it leaking, how did you know it was leaking?? The air springs are funny things really and can leak at one height and not at another, thats why its important to check for leaks by adjusting the vehicle to each height and then going round each corner with a bottle of soapy water (more soap than water really, you want it really bubbly). Spray this onto the spring and then look closely for any bubbling, this would indicate a leak. Check the bottom of the springs and then the air line connection at the top of the springs as well. If you haven't got the air line seated properly in the new spring then this will cause a leak. Lastly, why only replace one spring?? I did the one spring replacement thing just after I got my P38 and 6 months later I had ended up replacing all the rest of them, if one is going then the others are sure to follow sooner or later.

The EAS ECU controls every aspect of the system operation, the EAS pump wont run unless the ECU lets it, so when the pressure in the tank drops below a certain pressure, the pressure switch senses this and tells the ECU, the ECU then tells the pump to run.

There are four height sensors only, if you look under the vehicle you will see them attached to the frame rail with links down to the radius arms at the front and trailing links at the back. Usually, (when stationary) the EAS system will respond to a height change pretty quickly. You can see this effect by setting the vehicle at standard ride height and then get two adults (the larger and heavier your friends are the better for this ) to sit in the vehicle on one side only. As soon as they close the doors, there might be a 2/3 second delay and the vehicle will then compensate for the droop to one side and level it out. When you out and about driving, im not sure how long it takes to react to new readings, I wouldn't of thought it would respond too quickly because of differences in terrain etc.

On a height change it will adjust by an axle at a time (with the exception of going DOWN to access where it will open all 4 corner valves and drop the vehicle pretty evenly), rear first and then the front (this is to avoid dazzling other drivers when changing heights with lights on). If its reacting to a height change that been caused by load differences then it will adjust whatever springs that need to be adjusted.

When the vehicle is parked, in a perfectly perfect world, with no leaks or whatever then yes, it should stay level, but it usually wont. The EAS levels out the vehicle when you get out of it, then when you lock it it doesnt turn the EAS off so to say, it levels the vehicle every 6 hours from then on. Even if you have no leaks the height can change due to outside air temp etc.

The best and most easiest way to tell if you have a leak somewhere is to park up the vehicle and make sure its at standard ride height. Then remove keys, get out, DONT shut the drivers door, go round to passenger side and unplug the EAS delay timer (its under the passenger side and looks like a tall relay). Now close up and lock the vehicle and go to bed for the night. You have disabled the ability for the vehicle to self level every 6 hours. So in the morning when you wake up, note what corners are drooping and then go from there. Make sure to plug the delay timer back in before starting up.

My bet, like LSE, is a leak at the airline connection or on the bag itself.

Get yourself a copy of RAVE, it lists all the components of the EAS system as well as detailed explanations of how the system works.

Try the delay timer removal and see what you find.

-Wills

@v8kenny. I've not read the forum over there. I have looked at the site a few times but find it hard to find what I want. I will have a look on the forum now though. Thanks.

@wills. Thank you very much for the detailed reply. That explains a lot of what I was wanting to know. I will do the timer trick and see what it's looking like in the morning. I only fitted one air spring as I wasn't 100% sure that was the fault, but thought it couldn't do any harm. I will replace the others as and when they go

EAS is crazy.

Last night in the dark I was determined to find a leak. I wasn't disappointed. I found that hose where it goes under the battery mounting bracket had been chaffing. Hooray I though.

This morning I pulled the pipe out from underneath the front of the rad to get access to the damaged part. The damage didn't seem too bad so I started to car up so i could block the end of the pipe and make sure this damage WAS a leak. It was, As soon as I started the engine the loose pipe was flailing about.

I repaired the pipe by cutting out the damage and using a push fit through connector that I happened to have at work.

I poked the pipe back up and started the engine again before I connected the end to the air spring.

(This is where the head shaped dents on my wing and the wing shaped dents on by head and the boot shaped bruise on next door's cat's bum come from)...

I notice odd behavior now. It probably always did this, but with the pipe off, you notice it. First of all, air came out of the pipe at a fairly high volume so I connected it back and waited for the car to raise up. Nothing happened.

I took the pipe off the air spring again. There was some air in the spring as I could hear it de-pressurising when I took the pipe off. I started up the engine again and noticed that the volume of air from the pipe was dropping to nothing.

No matter how long I watched it (all door closed and dash light flashing showing that it is changing height) nothing comes out of the pipe.

I always thought that the symptoms didn't point towards a leak. Obviously the leak didn't help but there must be something else wrong

Sticking valve in the valve block perhaps, valve block "O" ring not sealing properly? Crook solenoid?

Driving home the car eventually came up to height. This morning there was no drooping in that corner. So I am happy now. It will go from normal height to access to normal quickly. But a second go takes longer. I suppose the reservoir is empty and the compressor is a bit slow.

Maybe now it's working "properly" I should sell the damn thing quick and get an S320 CDi

Mud Flap said:

Maybe now it's working "properly" I should sell the damn thing quick and get an S320 CDi

Click to expand...

How "very" dare you! on a brighter note im glad you found your prob! well it seems its cured, mine sometimes drops on the n/s/r but not always!!