P38A Odd EAS behaviour - sinking front

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300bhp/ton

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Anyone have a guess at the cause of this?

Bought another p38 recently (4.0 auto) with a known EAS fault.

Basically it wasn't raising at the front. It was thought an air spring might be the culprit. There were a couple of faults on the Nanocom, but I think due to the compressor running a long time. Cleared these and they have not reappeared.

Three times (including today) I've started the vehicle and both front and back have raised. In fact today I could cycle through all ride heights, stop the engine and restart and the EAS appeared fine. On the previous occasion, dropping to entry height and then trying to raise only the rear would come up.

The first time both front & rear worked I parked it up for 4-5 days. After which the front had sunk, but the rear was still raised. However, on other occasions (today after I'd finished messing with it, but other times too), you can turn the engine off and within 20 secs or so you hear a valve opening under the bonnet and it'll drop all 4 corners.

I honestly don't think it is an air bag at fault, as I'd expect more consistency with the issue. I do have 2 new front air bags however. But looking for suggestions on what the actual cause might be?

This is what it normally does when running:
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Although today for most of the time it was like this:
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When I first got it, it was showing these errors, but they have not returned, even when the problem is happening.
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First off as it's new to you, do the usual soapy water checks, ideally after it's risen & then engine off. It sounds like the pump is filling the tank ok as it does rise up when you want it to, but does sound like leaking airlines or valves in the block.

Could be a number of things such as the self levelling dropping the front but not the rear (although I never saw this) ?? In this case I would suspect the driver pack connectors underneath the valve block are intermittent, hence is not opening the rear but are lowering the front. Just in case get it off the grass & onto a level surface & pull the relay overnight.

Given the sensor error, check they are ok using multimeter. Clean the connectors just in case.

BTW most of your Nanocom screens are normal, i.e. front is low & tank is low so pressure switch is open & pump is running.
 
I would get it on flat ground first and then go back and check the heights. The front right does look out a little and maybe enough to cause an issue.
Then go from there to the next thing.. 👍
 
Thanks. So when the problem occurs the front does not rise at all. No need for the Nanocom to tell this. It’s more of why isn’t the front raising up when the rear has? Not so fussed on it sinking when off. But you can’t really drive the vehicle with the front on the bump stops.
 
Try removing the air line from the airbag and see if there is an air feed to while running.
Then go back to the block and see if anything is coming from the block🤔
 
Just a thought, the main connector in the eas valve box?
White connectors in the left hand kick panel?
You know where this is going 🤣
Full investigation time 🤭
 
Might be worth disabling the self-levelling overnight, either by pulling the EAS Relay or take out fuse F44. Then in the morning see if it still has dropped, in which case you have leaks somewhere.

After putting the fuse or relay back in allow the pump to fill the tank with door or tailgate open, before you try to raise it.

Remember when it's dropped, the ECU will always try to fill the rear first. If there's not enough air in the tank then the pump is trying to both fill tank and raise the car at the same time, which takes much longer.
 
It's usually the connector underneath the valve block between the driver pack & solenoids. The symptom is often "valve stuck closed" or similar faults, which the ECU reports if the car doesn't change height when commanded to.
 
Could be the front sensor signals aren't getting past the connector. Rear raises first then the front. If it runs out of air then the front won't raise. Usually that's a weak compressor from feeding a leak.
 
Lots of suggestions above :) I had a very similar issue on my previous P38, it was a long search and I would say i sort of stabilised it in the end. For the valve adjustments after you turn off then you can remove the EAS relay as suggested and replace with a normal one, this allows you to observe the car overnight. Forgetting the height sticks etc for a moment I would manually edit the bit counts so that you have less of a spread across each axle (esp. your rear) so that the ECU has less excuse to start self-levelling. I think the fact that the EAS was lifting rear and not front may well have been down to low pressure - when working on the EAS we tend to cycle it up and down way more than normal which will expose any system which is not 100% - the pump needs time (with the door open) to return to working pressure. I also had an issue in the LH passenger footwell with one pin from the white connector that had just crumbled away (before resoldering the whole lot. I also had a least one height sensor that was completely f***d and needed replacing, and then I had to replace its twin too... Good luck
 
Thanks, I won't look at it again until the weekend as the vehicle is not at home and currently has no MoT.

Really not fussed what it does when parked up. But currently you cannot drive the car when the front doesn't lift. But it is inconsistent. When it has worked, it has worked flawlessly and raises very quickly. So a leak or weak pump would not seem like logical fits.
 
Thanks, I won't look at it again until the weekend as the vehicle is not at home and currently has no MoT.

Really not fussed what it does when parked up. But currently you cannot drive the car when the front doesn't lift. But it is inconsistent. When it has worked, it has worked flawlessly and raises very quickly. So a leak or weak pump would not seem like logical fits.
I would be thinking electrical then🤔
 
My bet is still tank low or empty after a few days - hence slow to rise. Next time it's down at the front, just let the compressor run for 5-10 mins with door open. Then see how quick it rises with the tank filled.

When I have had the valve blocks out of either of my P38's, I let the tank fill first. Even then it's only enough air to raise the rear bags, but fronts only an inch or two. Remember the tank is only 10 litres. No idea what the bag capacity is, but my bet is somewhere between 6-10 litres each depending on height. At 120psi there's barely enough to fill two bags to 60psi, which is what's needed to raise it !!
 
My bet is still tank low or empty after a few days - hence slow to rise. Next time it's down at the front, just let the compressor run for 5-10 mins with door open. Then see how quick it rises with the tank filled.

When I have had the valve blocks out of either of my P38's, I let the tank fill first. Even then it's only enough air to raise the rear bags, but fronts only an inch or two. Remember the tank is only 10 litres. No idea what the bag capacity is, but my bet is somewhere between 6-10 litres each depending on height. At 120psi there's barely enough to fill two bags to 60psi, which is what's needed to raise it !!
With a full tank at about 140psi, both ends come up pretty quickly
 
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