MAF Diver · Jun 25, 2024

I've got ACE and SLS (airbags) in my D2a V8 4L and I've noticed two things when stopping at traffic lights:

1) Sometimes the rear will lower a little. It looks like the front is raising but obviously that can't be since it's got coils, right? Or can ACE do this?

Is that normal? Does yours do it too? Or is it a sign that the SLS is failing?

(I had the rear drop completely to the very lowest setting the other day when driving on a lot of curves and speed bumps. It then raised up later and I've never found it sagged in the morning.)

2) Sometimes shortly after braking to stop in traffic, the front will raise up very quickly like it's getting unstuck from something.

Is that an issue with shocks (probably the original ones still, after 75,000 miles on the clock), or is it something to do with ACE?

Andy Warren · Jun 26, 2024

Hi, this sounds like you have a leak somewhere. Mine had some odd behaviour in that it would never sink overnight even if it was left unused for a week but when driving & not always it would drop to the bump stops but if I stopped, turned the engine off then restarted it, it would re-inflate the air bags. It turned out there was a small hole in one of the bags but it always occurs under the folds where you can't see ! Try spraying soapy water on the bags/pipes etc to see if you can detect any leaks. DO NOT put any body parts between the trucks body or chassis e.g over the top of the rear wheels to spray the bags or get underneath it without axle stands/jacks in place to stop the body dropping, people have been seriously injured where the body has dropped unexpectedly ! (New drivers side air bag cured mine).

1988smithy · Jun 26, 2024

I'd be inclined to fit new bags as a matter of course depending on age and mileage covered by current ones

MAF Diver · Sep 17, 2024

So, I've got an update

Andy Warren said:
Hi, this sounds like you have a leak somewhere.

1988smithy said:
I'd be inclined to fit new bags as a matter of course depending on age and mileage covered by current ones

I changed the bags! (And also the shocks and front coils.)

Now I don't get those jolts anymore (problem 2 from my OP), but I still get problem 1:
- At traffic lights the rear gets lowered as I'm standing there with the brake depressed.

Then while driving it has to raise.

This seems really unnecessary? Or do all of them with SLS do it?

meego · Sep 17, 2024

MAF Diver said:
So, I've got an update

I changed the bags! (And also the shocks and front coils.)

Now I don't get those jolts anymore (problem 2 from my OP), but I still get problem 1:
- At traffic lights the rear gets lowered as I'm standing there with the brake depressed.

Then while driving it has to raise.

This seems really unnecessary? Or do all of them with SLS do it?

No, they don’t. Height should be consistent. You have either a compressor or height sensor fault if you have fitted new airbags. Or a leaking pipe somewhere !!

MAF Diver · 2024-09-26T15:50:01+0100

meego said:
No, they don’t. Height should be consistent. You have either a compressor or height sensor fault if you have fitted new airbags. Or a leaking pipe somewhere !!

How do I go about assessing this?

Leaking pipe: don't think so because the car doesn't lower when parked overnight (or longer).

Compressor or height sensor issue: could be. Someone also said it could be ECU?

But how to I eliminate/test? No errors come up in my OBD2

meego · 2024-09-26T17:10:58+0100

MAF Diver said:
How do I go about assessing this?

Leaking pipe: don't think so because the car doesn't lower when parked overnight (or longer).

Compressor or height sensor issue: could be. Someone also said it could be ECU?

But how to I eliminate/test? No errors come up in my OBD2

Raise the bags to full height and spray with soap/water mix and look for bubbles. (I know you have installed new, but better to rule them out) Trace the pipes and connections back to the compressor and check these in the same way. The compressor has seals and connections that can leak, so check there in the same way. Refurb kits for the compressor are available if that proves to be the issue. I’m not sure on an ECU being the issue or how to confirm this if your diagnostic isn’t picking it up. Perhaps a Nanocom would be better if that’s an option.

Polski Boschski · 2024-09-26T17:23:03+0100

Sell it.
Road tax cost is enough to not bother with them anymore

sierrafery · 2024-09-26T18:26:03+0100

MAF Diver said:
How do I go about assessing this?

Leaking pipe: don't think so because the car doesn't lower when parked overnight (or longer).

Compressor or height sensor issue: could be. Someone also said it could be ECU?

But how to I eliminate/test? No errors come up in my OBD2

OBD2 is useless in this case and it's not about a fault code as long as you didnt get the warning lights on provided they all work well on ignition self test. If you have a feeling that the front is raising not the back dropping it can be caused by ACE misbehaviour(unless it's just an impression and in reality the rear is dropping) so you must eliminate one suspect

1. Remove the ACE relay (R14) and drive it so to see if it's better or not(don't bother with the warning light, it will go out after you refit the relay) ...
2. if no change with ACE disabled remove fusible link FL9 to disable the SLS and see then(also neglect the warning lights)

in one of these cases the symptom should go away just tell when

MAF Diver

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1988smithy

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MAF Diver

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meego

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