Disco 2 ACE error 18 Closed loop pressure not under control
- Thread starter MJI
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sierrafery
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1. Which tool was used to retrieve the code?..if it was nanocom double check with other kind
2. can you see the fluid circulating well in the tank with engine running?
3. are you 100% sure that the rams were well connected to the valve block?
only one sensor can mpnitor that and that's the pressure transducer
2. can you see the fluid circulating well in the tank with engine running?
3. are you 100% sure that the rams were well connected to the valve block?
only one sensor can mpnitor that and that's the pressure transducer
1 Hawkeye
2 Yes
3 New pipes
Could it be a faulty transducer and is it the little thing on the front?
sierrafery
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I kow about new pipes... At 3 i asked if the rams are well connected to the proper ports in the block exactly as they were before ... front and rear of the actuator to the same ports where they were with original pipes cos if thsey are the other way around can cause that fault too... the transducer is a common fault http://www.discovery2.co.uk/ACE_transducer.html
sierrafery
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If you have hawkeye read live data ..if no pressure reading remove the relay and bridge the contact(30-87) then read again, if the transducer is good you must get around 20 bar but not less than 18 at idle
Worked perfectly for the first 5 miles
Then error 18 again.
Done a system test
Directional Valve 1
on 44ms
off 52ms
system 256
Directional Valve 2
on 36ms
off 108ms
system 336ms
Pressure valve
on 28ms
system 76ms
Block is pretty hot, if that is the issue
Then error 18 again.
Done a system test
Directional Valve 1
on 44ms
off 52ms
system 256
Directional Valve 2
on 36ms
off 108ms
system 336ms
Pressure valve
on 28ms
system 76ms
Block is pretty hot, if that is the issue
sierrafery
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Those readings are irrelevant for this, the pressure at idle is definitory for this fault... also as the block was drilled if then wasnt everything removed and cleaned 100% with compressed air as no iron filings to be trapped in it that could be a serious reason for missbehaviour.
Spent ages washing it through.
I had to redismantle as the hydraulic fitings were fitted without cleaning.
My removed block has fatter valves, would this be anything?
sierrafery
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I think you are not listenning... you have to rule out the transducer in the first place, then if that's 100% ruled out and you still dont get at least 18 bar reading at idle you can think of restricted flow... the pipes you fitted must have at least the same ID not below at the block connecction like the original ones, the solenoid's shape is not very relevant IMO, it's normal for the block to be warm cos it can get up to 135bar
jamesmartin
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this is interesting, pump and pressure control valve are physically responsible for system pressure,18 bar is quite high considering its an open center system at idle ie dcv both shut apart from the pump needing to be good enough to provide the flow and pressure presumably the pcv helps maintain this 18 bar,or is it just the restriction of pipe work and block drilings, ace system is unusual in that the return pipe is same diameter as feed pipe normally return is bigger so as not to create any restriction and so pressure/heat
sierrafery
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I didnt try to explain myself why it is that way but if you want i can make some research, on the first thought i can presume that the transduced pressure is not real but calculated how much would that be within the rams if the DCV's would open cos the real pressure is shown as being between 4-6 bar... the fact is that i've seen some cases of erratically reading transducer(not completyely failed) and the pressure shown was 16 or below while with a good one in the same system was 18 or above, that was verified on my own car as well... depending on the system's temperature and residual pressure i've seen cases when even 17 passed the self test so i presume that around that value would be the lowest accepted limit.
here are my readings with perfectly working system at idle:
system pressure = between 4-6 bar,
residual pressure = around 5.5 with small fluctuations, this one can vary from one case to another depending on temperature it's good between 0 - 6
pressure sensor(transducer) = 18 bar with very small fluctuations, when it was 16 with the old transducer the amber light was on
here are my readings with perfectly working system at idle:
system pressure = between 4-6 bar,
residual pressure = around 5.5 with small fluctuations, this one can vary from one case to another depending on temperature it's good between 0 - 6
pressure sensor(transducer) = 18 bar with very small fluctuations, when it was 16 with the old transducer the amber light was on
sierrafery
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i insist, those pressures are relevant
This is why I am going to refit the original block, solenoids and sensors as they are all known working
