E.A.S. Compressor pump poll.

I have spent ages going through the search section on this site,for anything about the e.a.s. compressor pump.
And it seems that there is no definite answer on how long the e.a.s. compressor pump should run/cycle for,whilst vehicle is being driven.
Now some say that when the air tank is full,there should be enough pressure stored for 3 changes in ride height before the pump activates again.
Others say that it is alright for the pump to be running on and off most of the time !
Now my pump ( with new seal ) runs for about 30 seconds and then stops for say 5-10 seconds continuously whilst being driven,is that good or bad i wonder ?

So is anyone interested in noting and placing in this thread how long their pump starts and stops, so we can all see the average time the compressor pump is running for in real world figures ?
Cheers Andy..

My Rangie sits at ride hight for however long I leave it (5 days max) so I assume no leaks on the springs. When I fire her up the pump kicks in and runs for 3 or 4 mins then stops. By this time I'm off down the road and loose the ability to hear if it ever comes back on. When I stop at lights etc and the suspension raises back to normal the pump will be running. It will go through a few cycles where logic is abandoned - could be on for 30 secs then off for 5 secs then back on for 2 secs then off again for 15 secs - eventually she will settle down and stay off.
I have often thought of wiring in a little indicator light so I can see how ofter the pump is running when I am driving. Like you I would love to know what is normal.

There is no reason your pump should cycle continuously if your system is indeed problem free. The pump is supposed to kick in at say 80psi and kick out at around 150psi. So unless your system has a big leak it should not come on every 15 seconds.
There is also a link to the braking system to give the effect of anti dive. i think it is this feature that causes the problem.

The likelyhood is that you have a failed/failing drive pack. It could be the pressure switch also but these are more rare a failure.

The best way to confirm is to put a pressure gauge in line with the reservoir to see what pressure you are getting in the tank. If this is getting upto the required 140/150psi then your compressor is ok. Watch for a while to see what causes the pump to come on and go from there. The compressor should not come on again until the pressure drops to around 80psi.

SpudH said:

There is also a link to the braking system to give the effect of anti dive. i think it is this feature that causes the problem.

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Spud ..Yer a fookin Genius!!!! .... I always thought there was a "Link" between brakin & my EAS pump kickin in .. but I could NEVER find it mentioned in Rave.

If I hit the brakes "Reasonably" hard I alway hear my EAS kick in...

Thanks for the replies :5bcheers2:

Like Spud says, i can't imagine the pump should keep cutting in, but i can't find a leak in my system doing the water test

I think i will try and find a inline gauge as mentioned next.

Also my suspension does not drop after 2-3 days of being left,and will lift from access mode to normal within approx 10 secs of being started !

Anyone else got any views ?

Andyp38 said:

Thanks for the replies :5bcheers2:

Like Spud says, i can't imagine the pump should keep cutting in, but i can't find a leak in my system doing the water test

I think i will try and find a inline gauge as mentioned next.

Also my suspension does not drop after 2-3 days of being left,and will lift from access mode to normal within approx 10 secs of being started !

Anyone else got any views ?

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According to RAVE, the cut in pressure of the EAS pump is 7.8 to 8 bar (104 to 116 psi) cut out pressure is 9.5 to 10.5 bar (138 to 152 psi) a narrower range than stated by SpudH. The running temperature of the pump is 120C, bloody hot
Worst case there is only 22psi between cut in and cut out, given that the system is constantly trying to self level which uses air, I would expect the pump to cycle quite often.

Datatek said:

According to RAVE, the cut in pressure of the EAS pump is 7.8 to 8 bar (104 to 116 psi) cut out pressure is 9.5 to 10.5 bar (138 to 152 psi) a narrower range than stated by SpudH. The running temperature of the pump is 120C, bloody hot
Worst case there is only 22psi between cut in and cut out, given that the system is constantly trying to self level which uses air, I would expect the pump to cycle quite often.

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i think datatek is spot on the system is constantly trying to self level which means as you go around corners , uneven road on a slope etc the height sensors are feeding differences to the ecu and therefore making constant adjustments to the air springs, putting more air in letting some out etc
once its allowed air out through the exhaust port if then it needs to put more in then this needs to come from the tank
as datatek says i would expect the pump to cycle quite often
unfortunately seems a rather inefficient system

As a p38 newbie,i'm learning a lot from this :clap2:

So is it logical to say that when running but parked on a flat surface,the compressor should not be running to often ?

Ive got a digital thermometer which im going to use to measure my compressors temp tomorrow,should be interesting !!

I must say that my own compressor runs a lot better since replacing the piston seal,even though the one that was in it looked in good condition.

Ive found a gauge with 6mm push in couplings on ebay,for about £20 which i'm going to get. Should be good for fault finding.

Andyp38 said:

As a p38 newbie,i'm learning a lot from this :clap2:

So is it logical to say that when running but parked on a flat surface,the compressor should not be running to often ?

.

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In theory yes but in practice maybe not. If you have ever heard a noisy volume control on a radio, the crackling hissing sound you can get as you try to alter the volume, well the potentiometers used as height sensors can do the same thing. This gives the EAS variable height readings which even when parked on the flat cause the EAS to adjust and hence the pump to cycle. If you have the bonnet open, the pump cycles continously for some reason.

Just had a read through the ETM section of RAVE and it says that while pressing the footbrake suspends any height changes that it is not intended to control dive. I'm not 100% sure about this though as certainly pressing the brake causes my compressor to come on and releasing it stops the compressor.
I def remember one of the air suspension experts on RR.net saying that he reckoned it operated the compressor directly to the front bags during braking.
And Datatek is spot on with pressures for on and off

SpudH said:

Just had a read through the ETM section of RAVE and it says that while pressing the footbrake suspends any height changes that it is not intended to control dive. I'm not 100% sure about this though as certainly pressing the brake causes my compressor to come on and releasing it stops the compressor.
I def remember one of the air suspension experts on RR.net saying that he reckoned it operated the compressor directly to the front bags during braking.
And Datatek is spot on with pressures for on and off

Click to expand...

Mine is Identical Spud.. I press the brake & me Compressor runs ..I lift off & it Stops .....I have noticed though if I go on a long(Ish) run it does stop happening

I can't find any reference to WHY the Comp runs when brakin in RAVE though..Unless I'm missin summott!!!

It sounds as though the compressor is almost overworked,with the things that cause it to operate.

Has anyone in the uk used a different compressor,like the one that rover renovations supplies ?

the hooded claw said:

Mine is Identical Spud.. I press the brake & me Compressor runs ..I lift off & it Stops .....I have noticed though if I go on a long(Ish) run it does stop happening

I can't find any reference to WHY the Comp runs when brakin in RAVE though..Unless I'm missin summott!!!

Click to expand...

Are you sure this is not the ABS pump you can hear? Operation of EAS is inhibited with brake applied. It cannot make height changes with brake on. Someone said earlier something about anti dip on braking. There is no such system other than the inhibition of EAS movement on braking. EAS is inhibited on braking so that any dip on application of brakes is not seen as a correction that is required as the sensors change position. There is no mechanism to lift the suspension on braking to counter dip. For one thing the system could not react fast enough to do this. So on braking the EAS is inhibited and locked in position untill the brake is released.

Can't say I have ever noticed the RR change height under braking but for sure my EAS pump is in someway connected to the brake pedal. Like Spud & Claw my pump will stop when I take the foot of the brake. Only notice this in traffic. There is no way it is the ABS pump.

jt_armstrong said:

Can't say I have ever noticed the RR change height under braking but for sure my EAS pump is in someway connected to the brake pedal. Like Spud & Claw my pump will stop when I take the foot of the brake. Only notice this in traffic. There is no way it is the ABS pump.

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The only connection, if you can call it that, from brake to EAS pump is the fact that the EAS is inhibited on brake application. In other words disabled until the brake is released. No movement is possible. If the pressure in the tank is above 120psi there is no connection of the EAS pump to power, as this is cut out by the pressure switch. The EAS pump CANNOT run if the pressure is above 120 psi as it is disconnected from the power supply.

jt_armstrong said:

Can't say I have ever noticed the RR change height under braking but for sure my EAS pump is in someway connected to the brake pedal. Like Spud & Claw my pump will stop when I take the foot of the brake. Only notice this in traffic. There is no way it is the ABS pump.

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I'm surprised you can hear the EAS compressor when you are in the car, especially in traffic. It's inaudible on mine. The ABS pump on the other hand.........................

The abs pump on my range rover sounds and behaves like the abs pump on my Ford sierra cosworth,in that it starts off pumping fast and then slows down until it stops after say 5-10 seconds from turning on ignition.
Then i dont hear it again until i have to restart the vehicle.

Also on my rangey the abs pump hums quietly on the offside when sat inside,where as the eas pump drones from the near side.

A test light could be rigged up from the eas pump into the cabin,to see which pump is making a noise though

Disconnect EAS pump, repeat press brakes, THAT noise is ABS. Parked, cycle EAS up `n` down THAT`s the EAS pump.

gtland said:

Disconnect EAS pump, repeat press brakes, THAT noise is ABS. Parked, cycle EAS up `n` down THAT`s the EAS pump.

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Pulled the relay next to the EAS ECU and the only thing I could hear is the ABS pump. Reconnected the relay and I hear the EAS pump loud and clear and it stops 100% of the time when I lift of the brakes. I'm starting to get paranoid with this thing now. Just about to wire up a test lamp to the fusebox relay output so I can monitor how often the pump is on during normal driving.

jt_armstrong said:

Pulled the relay next to the EAS ECU and the only thing I could hear is the ABS pump. Reconnected the relay and I hear the EAS pump loud and clear and it stops 100% of the time when I lift of the brakes. I'm starting to get paranoid with this thing now. Just about to wire up a test lamp to the fusebox relay output so I can monitor how often the pump is on during normal driving.

Click to expand...

I will repeat. EAS is disabled with brake on. No movement is possible, just as when you have a door open. Although compressor is still active if pressure is below 120 psi. If pressure in tank is above 120 psi the compressor is isolated from the power supply by the signal sent to the ECU by the pressure switch until pressure drops below that figure. Under normal circumstances the compressor CANNOT run unless the pressure drops below 120 psi, it is then shut off and isolated from power again at 150 psi. If pressure is above 120 psi and everytime you apply your brake the compressor starts, maybe the only thing to look at is the EAS ECU. Maybe you have a bad earth on the ECU and instead of the pedal switch isolating the EAS it is interacting because of earth flow and activating compressor relay.