P38a EAS testing

Hi all,

As per other thread, I've been testing the air springs on the Rangie today, by leaving it parked with/without the tailgate open (to inhibit self-levelling) and measuring the height from the ground to the wheel arches. I estimate my accuracy of measuring to be about +/- 1mm or so.

Test 1: Wading height (highest manual setting), self levelling inhibited All maintained height to within +/- 2mm over 1 hour 45 minutes

Test 2: Wading height, self levelling automatic (without resetting) All maintained height over 1 hour 30 minutes to within +/- 1mm

Test 3: Normal ride height, self levelling automatic All maintained height over 1 hour 30 minutes to within +/- 1mm except left rear which dropped from 815mm to 811mm

So, with the possible exception of the left rear spring, my springs appear to be leak-free at this ride height over periods of a couple of hours. I'll check the height difference overnight when I can leave it on a flat surface overnight.

I have found in the past that it settles on to the bump stops over about 4 days. Is this normal? At this point it took a long time to get to normal ride height (probably about 5 mins), presumably because the reservoir itself was empty.

The reason I did all this was because (as mentioned before) I seem to be losing air in normal use, because the compressor seems to run quite a bit. Even when parked at the petrol station it recharges the reservoir for several minutes after a couple of minutes standing.

So, it looks like I'm either losing air from somewhere other than the springs, or I'm losing air from the springs but only noticeably when the vehicle is moving. No obvious air bubbles from the valve block inputs when I spray them with soapy water. What should I check next?

Could I be losing air from the valve block itself - ie, when the block is active because the springs are moving up and down, air is escaping from part of the block? How about the reservoir, or the link from the reservoir to the block? Any common problems with this area I should check?

Also, does anybody know the threshold the auto-levelling operates on? ie, how much difference before it levels?

Thanks, David.

Reply to
David French
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David> Test 1: Wading height (highest manual setting), self David> levelling inhibited All maintained height to within +/- 2mm David> over 1 hour 45 minutes

David> Test 2: Wading height, self levelling automatic (without David> resetting) All maintained height over 1 hour 30 minutes to David> within +/- 1mm

David> Test 3: Normal ride height, self levelling automatic All David> maintained height over 1 hour 30 minutes to within +/- 1mm David> except left rear which dropped from 815mm to 811mm

David> So, with the possible exception of the left rear spring, my David> springs appear to be leak-free at this ride height over David> periods of a couple of hours. I'll check the height David> difference overnight when I can leave it on a flat surface David> overnight.

Over 1-2 hours self levelling will not activate - it's a six hour cycle. Leaks can show at one height and not another as the springs operate - if you've seen one out of the car it's obvious why, but hard to explain in an e-mail.

David> I have found in the past that it settles on to the bump David> stops over about 4 days. Is this normal? At this point it David> took a long time to get to normal ride height (probably David> about 5 mins), presumably because the reservoir itself was David> empty.

Yeah, that would tie in with my experience.

David> The reason I did all this was because (as mentioned before) David> I seem to be losing air in normal use, because the David> compressor seems to run quite a bit. Even when parked at David> the petrol station it recharges the reservoir for several David> minutes after a couple of minutes standing.

Air leak to the reservoir itself?

David> So, it looks like I'm either losing air from somewhere David> other than the springs, or I'm losing air from the springs David> but only noticeably when the vehicle is moving. No obvious David> air bubbles from the valve block inputs when I spray them David> with soapy water. What should I check next?

Check the visible bits of the springs. Might be worth pulling the wheelarch liners to get some access.

David> Could I be losing air from the valve block itself - ie, David> when the block is active because the springs are moving up David> and down, air is escaping from part of the block? How David> about the reservoir, or the link from the reservoir to the David> block? Any common problems with this area I should check?

Comment about the reservoir above. The other thing to look at is the possibility of the diaphragm valve not closing properly which could cause air to go stright out of the system instead of into the compressor.

David> Also, does anybody know the threshold the auto-levelling David> operates on? ie, how much difference before it levels?

ISTR the difference level is +- 2 "bits". The height values are measured as 0V to +5V and stored internally as a number between 0 and

255. This is referred to, somewhat inaccurately, as a bit count. So +-2 corresponds to something like 0.04V change coming back from the sensor.

I think to prove where the fault is happening you need to hook up a pressure test gauge to see what's actually happening to the air reservoir. Instructions on making on are on my site, or you can buy the official LRT-whatever for about 70 quid + VAT.

AndyC

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+-------------------------------------------------------------------------+ |Andy Cunningham aka AndyC the WB | andy -at- cunningham.me.uk | +-------------------------------------------------------------------------+ |
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Reply to
AndyC the WB

I can see why that would be the case, having had a butchers at the springs. That's partly why I tried two different ride heights. I can try a third by booting it down the motorway and then over-riding the ride height change - something for another day. However, if it's leaking at a certain height, I'd also expect it to stop leaking before it hit the stops, unless the leak is near the bottom of the travel anyway.

What I've done today has hopefully isolated any leak from being related to the springs. Ergo, it should probably be down to the reservoir, hoses, valve block, or possibly the compressor, although it did occur to me the emergency overload valve could also be a culprit? Hey, I'm nearly there!

This would seem to make sense as it seems to be losing pressure when moving, rather than when stationary, and this is the point at which the connection between the reservoir & springs is being made through the valve block, rather than being isolated which is what happens when it's stationary.

Like I said before, it's not actually gone wrong yet, but I'm trying to be cunning and head it off before it gets too bad, as this could save me money on replacing a knackered compressor.

D
Reply to
David French

Dave,

just a thought about leak testing

On my classic I can disconnect the ECU, and manually pump up each corner (you just need the pin outs and 4 pieces of wire that are linked together).

Basically, you energise the compressor, open the "air supply on" valve, then select the relevant valve for the corner.

Recently I buggered up my suspension (50 yds of clay turf) and made the ECU go into "fault" mode. To get it off the bump stops I pumped up each corner.

For your leak testing I would do the same thing, then leave the ECU disconnected, and if any corner moves, you've either got a valve, airbag or piping problem.

here's the link

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I now keep a 4 headed bit of wire in the glove box, with a list of pinouts

Si

Reply to
simonk

David> I can see why that would be the case, having had a butchers David> at the springs. That's partly why I tried two different David> ride heights. I can try a third by booting it down the David> motorway and then over-riding the ride height change -

??? You can get all four in the driveway.

David> something for another day. However, if it's leaking at a David> certain height, I'd also expect it to stop leaking before David> it hit the stops, unless the leak is near the bottom of the David> travel anyway.

True.

David> Like I said before, it's not actually gone wrong yet, but David> I'm trying to be cunning and head it off before it gets too David> bad, as this could save me money on replacing a knackered David> compressor.

Yes. I know I have a small air leak, but it doesn't seem to be enough to cause excessive compressor running, so I'm not too bothered (it's been there for at least 2 years now).

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+-------------------------------------------------------------------------+ |Andy Cunningham aka AndyC the WB | andy -at- cunningham.me.uk | +-------------------------------------------------------------------------+ |
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- Everything you wanted to know || about the P38A Range Rover but were afraid to ask. |+-------------------------------------------------------------------------+"And everything we want to get/We download from the InternetAll we hear is/Internet Ga-Ga/Cyberspace Goo-goo" -- from "Radio Ga Ga"/"We will rock you"
Reply to
AndyC the WB

I can? If I use the switch it just moves between normal ride height and crawl height - it won't go to motorway setting unless it decides to do it by itself. I'm missing something...?

Reply to
David French

Does this work for P38 anybody? Not sure where the similarities between Classic and P38 EAS end.

Sounds like something to have in the glove box OK.

Tx David

Reply to
David French

David, one thing you could try is replacing the air drier, located at the front left of the radiator, if the system is going under pressure, the compressor is having to work hard, even harder if its trying to work against a filter thats blocked with water.

Last time I enquired, the price was about £30 genuine.

Alistair

Reply to
Alistair

David> I can? If I use the switch it just moves between normal David> ride height and crawl height - it won't go to motorway David> setting unless it decides to do it by itself. I'm missing David> something...?

Push the inhibit switch and it should go to motorway level regardless of what you're doing. The inhibit switch gives you manual control of the two levels as well as overriding automatic changes.

For the benefit of anyone else not 100% familiar with the more obscure functions, you can also select access mode then press inhibit switch to stop it lifting from access mode when you drive off. This is known as "crawl mode" and is very useful when you get to a 6' height barrier!

AndyC

Reply to
AndyC the WB

David> Does this work for P38 anybody? Not sure where the David> similarities between Classic and P38 EAS end.

Yes, it will work for P38. If you can find a scrapped EAS ECU you can build up a connector and some switches to do it really neatly. In terms of the EAS, there are two main differences between the classic and the P38A. The first is that the components which sit in the engine bay on the P38A are in different locations, and the second is that the P38A ECU has more refined software which is less susecptible to going into limp-home mode if you hit a pothole or similar.

Having said that, I don't know how much, if any, of the components are acutally interchangeable.

AndyC

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+-------------------------------------------------------------------------+ |Andy Cunningham aka AndyC the WB | andy -at- cunningham.me.uk | +-------------------------------------------------------------------------+ |
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- Everything you wanted to know || about the P38A Range Rover but were afraid to ask. |+-------------------------------------------------------------------------+"And everything we want to get/We download from the InternetAll we hear is/Internet Ga-Ga/Cyberspace Goo-goo" -- from "Radio Ga Ga"/"We will rock you"
Reply to
AndyC the WB

Alistair> David, one thing you could try is replacing the air Alistair> drier, located at the front left of the radiator, if the Alistair> system is going under pressure, the compressor is having Alistair> to work hard, even harder if its trying to work against Alistair> a filter thats blocked with water.

I wouldn't worry about this unless there is water in the system. Of course, now that temperatures have dropped, any water in the system will freeze and cause real fun.

The important one is to make sure the inlet air filter has been changed at the appropriate intervals.

AndyC

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+-------------------------------------------------------------------------+ |Andy Cunningham aka AndyC the WB | andy -at- cunningham.me.uk | +-------------------------------------------------------------------------+ |
formatting link
- Everything you wanted to know || about the P38A Range Rover but were afraid to ask. |+-------------------------------------------------------------------------+"And everything we want to get/We download from the InternetAll we hear is/Internet Ga-Ga/Cyberspace Goo-goo" -- from "Radio Ga Ga"/"We will rock you"
Reply to
AndyC the WB

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