Disco 2 ACE error 18 Closed loop pressure not under control

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MJI

MJI

Well-Known Member
Posts
16,841
Location
Worcester
Happens erraticaly

New pipes, rear bar, ACE block is SH refurbished.

pump and ECU are OK

Any ideas please?

No fluid leaks.

Could it be air in the system?

If sensors, which one?
 
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
 
sierrafery said:
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
Click to expand...

1 Hawkeye
2 Yes
3 New pipes

Could it be a faulty transducer and is it the little thing on the front?
 
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
 
See my other thread, definately correct as it works sometimes, (had at limit of adhesion on a roundabout)
 
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
 
Pressure was lower than that at idle but over 110 bar when cornering OK.

I will live data again tomorrow and check
 
I did work out plumbing and found that the bottom one on the chassis was 3rd on the block, 95% sure plumbs correctly.

Block had not been used in over a year and was of unknown condition.

I do still have my old block
 
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
 
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.
 
sierrafery said:
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.
Click to expand...

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?
 
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
 
sierrafery said:
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
Click to expand...
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
 
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
 
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