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Sound like non standard pressure switches.
There was someone a while back who changed to a 100/120 switch. Pump ran a lot less but the EAS still worked OK
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P38A EAS question
- Thread starter rangie1998
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There was someone a while back who changed to a 100/120 switch. Pump ran a lot less but the EAS still worked OK
Datatek
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When the suspension ECU lowers pressure in an airbag, the air has to go somewhere so it leaves via the exhaust. If subsequently the pressure needs to increase, then the tank pressure will reduce to provide the air needed. The compressor switching back on at 135psi does seem too early, 10psi between on and off is not a lot. Might be worth checking and/or replacing the compressor relay.
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Have the nrv's been checked for wear inside the block?
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FYI, I checked a couple of pressure switches today on the bench. Fed the valve block using a Mercedes Wabco pump, so it gets up to pressure quite quickly. Both switches close about 135-138psi, and open again around 121-126psi. Tried with analog dial & digital gauges, and same result.
On a side not found the spare block has a small leak between main gallery & rear left corner. That would explain why the car used to rise up a bit at the back when parked !!
On a side not found the spare block has a small leak between main gallery & rear left corner. That would explain why the car used to rise up a bit at the back when parked !!
Datatek
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According to my version of RAVE, the pressure switch closes at 140psi and opens at 120psi so your figures are not far off. The drawings indicate that the compressor is not directly controlled by the pressure switch but by the ECU.
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I have just replaced my compressor (brand new Dunlop) and valve block (refurbed from a X8R kit). As far as I can see I now have no leaks anywhere, and the kit is all new.
I went for a good 12 mile drive on Saturday with the Nanocom recording and this is what we saw. @pwood999 was good enough to convert my trace to a graph for me.
Here is the csv if you want to have a look.
I submit it only as an idea of how long a compressor should run for with no leaks and new everything... But as you can see, after an initial charge of the tank, it only really runs in fits and starts.
I went for a good 12 mile drive on Saturday with the Nanocom recording and this is what we saw. @pwood999 was good enough to convert my trace to a graph for me.
Here is the csv if you want to have a look.
I submit it only as an idea of how long a compressor should run for with no leaks and new everything... But as you can see, after an initial charge of the tank, it only really runs in fits and starts.
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rangie1998
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Hi, yes I have 2 spare valve blocks so I've used the best nrv's from all 3. Replaced the o rings with the ones in the kit from xr8.
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All the RAVE versions show those values. Strangely the EAS SID has different values, but does state 56psi allowable deviation !!
And this
Attachments
Datatek
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The first one is not relevant as far as I'm aware as it's a carry over from the Classic. the second one is closer, my version of RAVE shows the values below.
rangie1998
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Thanks for all your replies.
Changed both relays, no change. Checked wiring behind front passenger footwell panel, all seems ok.
Disconnected the pump, pressure was showing 140psi. Went for 3-4 mile drive and pressure had dropped to about 90psi. Does this sound normal? Seems a lot to me. Solenoids do seem to work a lot.
Attached is video showing pressure guage on line to tank. This was when pressure had reached 145psi, open and slamming door few times, to create movement, this is what happens. Can hear solenoids clicking, air escaping exhaust. Just continues to cycle like this.
Changed both relays, no change. Checked wiring behind front passenger footwell panel, all seems ok.
Disconnected the pump, pressure was showing 140psi. Went for 3-4 mile drive and pressure had dropped to about 90psi. Does this sound normal? Seems a lot to me. Solenoids do seem to work a lot.
Attached is video showing pressure guage on line to tank. This was when pressure had reached 145psi, open and slamming door few times, to create movement, this is what happens. Can hear solenoids clicking, air escaping exhaust. Just continues to cycle like this.
Datatek
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No video. I still say there is/are leaks from the airbags.
rangie1998
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I've uploaded it to you tube, here is the link.
Thanks for your help Datatek. I'll change the bags, might be worth doing the height sensors as well.
Thanks for your help Datatek. I'll change the bags, might be worth doing the height sensors as well.
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So the pump is stopping to allow the ECU to adjust the heights (clicking solenoids in background). Then the pump starts again.
I'm assuming that as the gauge is showing 9.5bar (137psi), the pressure switch is still open, hence the pump runs in between height adjustments.
Repeat with door or tailgate open to prevent height adjustments, see if the pump reaches 140psi. With height changes disabled, it should run to either the pressure switch point, or until overheat !!
I'm assuming that as the gauge is showing 9.5bar (137psi), the pressure switch is still open, hence the pump runs in between height adjustments.
Repeat with door or tailgate open to prevent height adjustments, see if the pump reaches 140psi. With height changes disabled, it should run to either the pressure switch point, or until overheat !!
Datatek
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The pressure switch is not very precise.
rangie1998
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Tried it leaving a door open, will reach 145psi then turn off. Also tried a different ECU, same problem.
There's two issues, 1. The height adjustments are far too often, 2. The pump is turning on before it's dropped to 110-116psi.
I'm going to try rebuilding one of my spare valve blocks and see if there's any difference.
Datatek
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The pump should turn on at 120 psi.
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Bingo, height adjustment will consume the air, hence the pump running time...
That's why I asked ages ago with no reply.....sort the heights and the system will settle down I guarantee it...
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Calibration of heights is easy enough.
On a trace the pump should run less than 30% of the time. And I agree the pump should cone on roughly between 120 and 140 psi.
On a trace the pump should run less than 30% of the time. And I agree the pump should cone on roughly between 120 and 140 psi.
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Swapping ECU requires height calibration becasue the two ECU will have different target heights. Read all the Stored & Actual heights from the ECU you are using & post them here. Then we can tell if you need to calibrate it.
Did you check the valve block for leaks after doing the refurb ?
Take a good look at Post #26 above. This shows how the pump should behave after a valve block refurb and height calibration.
This is McGorsky's before the refurb. Notice the pump (blue line) is running almost continuously, whilst the Inlet & exhaust valves (orange & grey) are opening & closing quite a lot. Continuous adjustments like this indicate calibration errors.
Did you check the valve block for leaks after doing the refurb ?
Take a good look at Post #26 above. This shows how the pump should behave after a valve block refurb and height calibration.
This is McGorsky's before the refurb. Notice the pump (blue line) is running almost continuously, whilst the Inlet & exhaust valves (orange & grey) are opening & closing quite a lot. Continuous adjustments like this indicate calibration errors.
rangie1998
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Thank you. My apologies for missing your previous post. A friend did connect it to his laptop with software installed, height sensors were all within tolerance. Will check it again and the calibration. ThanksBingo, height adjustment will consume the air, hence the pump running time...
That's why I asked ages ago with no reply.....sort the heights and the system will settle down I guarantee it...
