different air suspension pain 4.8is

[pieter4458]

Originally Posted by sockethead

I found that when the air bags wear out, it's not really a hole per se, the bag it literally worn out and a whole area will become porous. When you spray the bag with soapy water, it may not just bubble up in one spot like it would with an obvious hole, it will kinda foam up in the area that has become porous.

How are you resetting the inactive warning? do you have DIS? If so, that will tell you why the message came on in the first place. Then you need to run through the test plans. It should have a test plan already loaded from the error. It tests compressor, Accumulator fill and vent and a few others if I remember correctly.
You can also test individual components.

Intermittent issues like you are having can be very frustrating. Our 4.8 has had the inactive warning for about 6 months. DIS reports that the error is an accumulator fill error. After extensive testing by me and BMW, we all *think* that the compressor may be weak but we're not willing to spend $500 to find out so I live with the error on the dash. All of the air bags have been replaced as they failed one right after the other.

The statement: "we all *think* that the compressor may be weak" is true and it can be the problem on mine as well. A few moths ago a technician tested mine and found the armature to be full of carbon and the relay points burned, due to the bad feedback from the pump.

[TwinsPoppa]

Originally Posted by sockethead

I found that when the air bags wear out, it's not really a hole per se, the bag it literally worn out and a whole area will become porous. When you spray the bag with soapy water, it may not just bubble up in one spot like it would with an obvious hole, it will kinda foam up in the area that has become porous.

How are you resetting the inactive warning? do you have DIS? If so, that will tell you why the message came on in the first place. Then you need to run through the test plans. It should have a test plan already loaded from the error. It tests compressor, Accumulator fill and vent and a few others if I remember correctly.
You can also test individual components.

Intermittent issues like you are having can be very frustrating. Our 4.8 has had the inactive warning for about 6 months. DIS reports that the error is an accumulator fill error. After extensive testing by me and BMW, we all *think* that the compressor may be weak but we're not willing to spend $500 to find out so I live with the error on the dash. All of the air bags have been replaced as they failed one right after the other.

So, what were the results of the test plan? What were the results of individually testing the accumulator and compressor?

Maybe try and find a used air supply unit, throw it in there and see what happens.

[sockethead]

Originally Posted by TwinsPoppa

So, what were the results of the test plan? What were the results of individually testing the accumulator and compressor?

Maybe try and find a used air supply unit, throw it in there and see what happens.

I hate to hijack this thread but this is usefull info for everyone, I hope.

It passes all of the tests in DIS but as soon as the code is erased and the system is put back in normal mode, it produces an accumulator fill error. Otherwise, the system holds air normally and the suspension rides normal as you guys saw at Bimmerfest. That's why I've basically side F' it and am just living with it.

I guess if we knew how many bars the pressure is supposed to rise in a given period of time, we could deduce from that info if the compressor is really bad or not

One of the senior techs at Kristen's dealership had a used pump for me to try out but it was for a single Axel suspension and the wire harness was completely different.

[TwinsPoppa]

Originally Posted by sockethead

I hate to hijack this thread but this is usefull info for everyone, I hope.

It passes all of the tests in DIS but as soon as the code is erased and the system is put back in normal mode, it produces an accumulator fill error. Otherwise, the system holds air normally and the suspension rides normal as you guys saw at Bimmerfest. That's why I've basically side F' it and am just living with it.

I guess if we knew how many bars the pressure is supposed to rise in a given period of time, we could deduce from that info if the compressor is really bad or not

One of the senior techs at Kristen's dealership had a used pump for me to try out but it was for a single Axel suspension and the wire harness was completely different.

Its hard to accept that the dealer doesn't have more avenues for diagnosing. I guess they don't have enough experience with that particular problem?

I found this info. but the dealer would know already.

"The EHC 2 control module monitors system pressure via a pressure sensor mounted on the accumulator. Normal system pressure is 15.7 +/- 0.7 bar. Minimum system pressure is 9 bar. The pressure accumulator's charge is sufficient to fill the four suspension struts once from the Access position to the normal position and compensate for vehicle load up to maximum gross weight."

IIRC, difference between Access (lowest) and Normal ride-height is 20-25mm.

[sockethead]

Hmm, I don't remember it getting that high during the testing... I'll have to retest.

The dealer would probably just put a new compressor in it if it was a normal customer but since they were doing us a favor, they just tried to diag for us.

[Ricky Bobby]

Originally Posted by sockethead

Hmm, I don't remember it getting that high during the testing... I'll have to retest.

The dealer would probably just put a new compressor in it if it was a normal customer but since they were doing us a favor, they just tried to diag for us.

What is the exact error you are getting in GT1/DIS? Is it EHC 74 accumulator pressure remains constant/filling requested? No other errors, all bags replaced right?

If so, that was my exact problem, compressor was working and held air fine on all corners, but from driving with leaking bags from previous owner, the compressors life was shortened and it was out of spec which threw the error. Replaced my compressor (with a gently used one, off a NON leaking car) and no more error and ride height control works!

[sockethead]

Originally Posted by Ricky Bobby

What is the exact error you are getting in GT1/DIS? Is it EHC 74 accumulator pressure remains constant/filling requested? No other errors, all bags replaced right?

If so, that was my exact problem, compressor was working and held air fine on all corners, but from driving with leaking bags from previous owner, the compressors life was shortened and it was out of spec which threw the error. Replaced my compressor (with a gently used one, off a NON leaking car) and no more error and ride height control works!

Yep that's the exact error... That confirms that its the compressor. Awesome!, thanks.

[pieter4458]

I monitored my vehicle since my last post and noticed the following:

1. The height on all 4 corners stays more or less constant over a period of 14 days.
2. The reset of the error code only lasted 7 days before the stupid "air suspension inactive" message appears (again)
3. After the error message appeared the vehicle lifting button inside the vehicle becomes inactive
4. The pump kicks in when the car is unlock, but :

4.1 the sound of it is "hard and coarse" like a Taiwan wheel pump
4.2 The pumps speed gets slower after 20 seconds - like it is pumping against an obstacle until it stops.


Question:
Can the Pressure switch on the accumulator be the culprit telling the pump to fill, but due to the fact that the tank is already filled the pump struggles?

or

Is the Pump just faulty and cannot provide the needed pressure to the accumulator?. (remember the corners does not drop)

But why does the reset of the error code only last 7 days?

I am confused.

[sockethead]

Sounds like you have the same problem I do( see my posts in this thread) my air pump sounds the same way. When it first started happening the error would take a day or two, maybe more, then it got worse from there.
You need to get the actual error code from the suspension module before resetting. If it is an accumulator fill error like mine, then you need a compressor

[pieter4458]

Is there a way to recondition the compressor? A new one will cost more than a arm and a leg