Ok I will go to Maplins tomorrow with this diagram and see if anyone can sort me out.
Can you sense check that what I'm asking is correct though.I want two potentiometers 10k ohms and 1k ohms and a 100 ohms resistor. These have to be rigged together as per diagram with 2.5 meters of speaker wires spare at each side to reach cab.
Hopefully the guy wont ask me for the maths behind it as I will be a rabbit in the headlights
The objective is to adjust the rig to i930 readings to sit within good start window (under 14 degrees or above 69 degrees)
Is this all correct ?

That's it yes, exactly.
The guy in maplin should show you how to wire it up - especially how to wire the potentiometers up. (there are only three pins on each pot and you connect the middle pin (the wiper) to one of the outer pins - then there are two connections left - the outer ones effectively - which way around you put it in the circuit only affects the direction you need to turn it to increase or decrease the value.
If in doubt, post an image of what you get and I will help.
Try to think about how you will mount the bits - again the guy in maplins should be able to advise. But you don't have to do anything fancy. a bit of plastic and some hot glue can be used to mount the components on and then solder them - anything really as it is only temporary. If you want a more permanent solution maplin will sell you a tiny plastic box which is great. the pots (depending on type) can have a screw thread for mounting through a hole in the box, or you can use tiny pcb mounted pots and a thing called vero board, or proto board. However, the easiest by far to assemble is by using a very small plastic box and the pots with nuts on - he will show you. no worries. .. you will be fine...
Joe

Ok got the parts from Maplins and believe I have soldered in line with diagram. I will attach to cts plug later and see if it works. If its not been done correctly please just let me know

to cts plug later

REDNAL3 said:

Ok got the parts from Maplins and believe I have soldered in line with diagram. I will attach to cts plug later and see if it works. If its not been done correctly please just let me know

View attachment 105367 to cts plug later

Click to expand...

Hey nice one ! - Looks great - well done !
you will need to play with the pots with the ignition on and 930 attached.. but - to start with, you can just hook your multimeter to start with for now and play about -
You will see how - for example, with the 10 k wound down to 0 that the 1 k pot allows fine adjustment of the higher temps - and the 10 k allows adjustment of the lower temps - play around with your meter - and again - well done that man !
Joe

Refer to this table for a guide - resistance measured across the two green wires of your circuit (the wires that go to the cts plug - in relation to temp

REDNAL3 said:

Ok got the parts from Maplins and believe I have soldered in line with diagram. I will attach to cts plug later and see if it works. If its not been done correctly please just let me know

View attachment 105367 to cts plug later

Click to expand...

Shouldn't the resistor be connected to the centre of the bottom pot. Marked red in this pic.


Edit: it is connected. I need new glasses
Looking good

Well done Joe the rig works exactly as you advised it would. The coolant was at 45 degrees well within the non starting window. I set the coolant reading to 14 degrees and the engine started straight away.Interesting however If I put it to 70 degrees or above for example which is normally within the good start window the car wont start. Would this suggest that the rig set at low temperature is masking the true fault rather than over riding a suspected ECU fault. ?

Hi, firstly well done for building the test rig properly. Nice job.
Ok, well your results you have make me suspect a few things.
Firstly, I am not convinced your 'window' exists.
Yet again, more tests are needed but at least we have the tools.
Ok, you said before that when the coolant ACTUALLY WAS 70C it started ok. Well, we need to actually confirm that as it may have been something that is not always repeatable.

You need to make notes of all the results of the following -
Test - run car until the temperature actually DOES reach 70 or greater (with normal cts attached) and 930 monitoring.
Now, stop it and try and restart. Does it start ?
If not, then the window theory is wrong.
If it does, then now quickly connect the rig and set the temp to 50c (whilst the REAL engine temp is actually 70 C or more )
Does it start now at a manually set 50C with the rig ? note if it does start or not.
then drop the temp on the rig to 30C (with engine stopped)
Does it start now ? ?
This all needs to be done quickly so as not to let the engine cool below 70C (Actual temp!)

Whatever the results, now re-connect CTS and check the actual temp - note the temp and try and start. Does it start or not ?

If your 'window theory' is correct then with a genuine coolant temp of >70C the engine WILL start.
If you then use the test rig and set the temp to 50C according to your theory it will NOT start.
That is what we need to check.

As said, you now have the test gear, but have not got definitive results - only theories.
You have seemed to prove that at around 45C Actual - if you set the ecu to read 70C or greater it will not start. That tells us part of the story but not all.
By getting the engine to an actual of > 70 and then manually lowering the temp with the rig, if the window exists then it will not start at - say - 50 - but when manually raised to 70 again it will. Also, immediately after that, with cts attached (presuming it is still actually 70 or more it will also start.

Personally I find the theory of a window (a repeatable one) being implausible - however - that is what we are testing. If it does exist it tells us one thing - if it does not, it tells us another thing.
So, - get your notebook out and start doing some more diagnostics with your super cts simulator and 930

Hi Joe, Yes I will definitely try reducing the temp to 40 with rig when the true coolant temp is 68 or above and see what happens.
I do know without shadow of a doubt though that the car will restart every time if true coolant temperature is above 68. I only know this as I have been doing this test extensively over past few days at progressively different temperatures to try to pinpoint the top end non start window temperature.This result is repeated regardless on whether the cts plug is attached or removed. (I attach cts plug as required to check true temp after each test)
At 68 or above I can switch off and easily restart as many times as I wish. I guess at that temperature the cylinders are already so hot it doesn't take much to fire up.
Tomorrow I will get it up to 70c true temperature, introduce the rig and select a couple of lower temperatures.to see what effect it has.
My kids can now use the i930 scanner. Its a prerequisite of giving them a lift that they monitor the readings,

can you 100% confirm though that when the temperature is - say - 55 (not on the way DOWN form 70, but on the way UP from cold) that you CANNOT stop it and restart it. - Have you tried it.
It is completely different to let the temp rise to a certain level - for example 75 c(starts ok) and then let it cool to - for example 60 (doesn't start ok, than to let the temp rise to - for example 60 and no more and then stop and try to restart it.
The difference is HUGELY important.

Also, you know that with CTS unplugged and back up mode enabled it will always start as it applies a -10c fuelling map and heaters so repeating this too much is pretty pointless. All it tells us is that the vehicle - for some strange reason - appears to need a lot of fuelling to start.
The trouble with your tests when the engine IS over 70 actual is that the temps do not stay at this level long if you leave it - then it will no restart. We do not know at this stage if that is due to the temperature dropping, or the actual time related between stopping and then trying to restart as as time passes so the temp drops. One can easily be fooled by things like this.
This is why the - stop at 50C or 60C ACTUAL - CTS NORMAL - on the way UP to temp and try to start it is important - Does it ? (again to stress, this is completely different then letting it cool down to 60 from 70.
IF it starts ok immediately after a run to where the temp actual is up to 50 or 60C, then the issue is not a 'window' - it is a time from stopping issue.
I hope you can see the differences here ? - dont become fixated on a single issue (for example this 'window') look at all options and test them.
It could - as I say, be that you start it cold, monitor the temps with the 930 until 50 - 60 is reached, then stop and restart and see if it restarts immediately - it may well do. !
If it does, (this is immediately after the temp REACHES 50/60C on the WAY UP) then quickly plug in the cts replacement tester and try it at 80, then 30 (from the tester unit you made). Again, you have to be QUICK whe doing these test to determine if the issue IS temp related OR time after stopping related.
Does all that make 100% sense to you mate ?
Joe

A few more readings to take - I cannot see these readings in the earlier posts.
When cold - without starting - ignition on, what is the HP pressure and LP pressure (not whilst cranking, ignition on only and engine not having been started for a considerable time - as - for example - first thing in the morning)
Also, same readings recorded when up to temp having run. Engine stopped - ignition on - not cranking- temp actual round 70C or more.)

Then after the above test (the 70C or more) - without starting the engine at all between tests - record the same readings after the temperature actual has dropped to around 45 / 50C - or when car has been left for 20 or 30 mins.
You should be able to include some of these tests in with the others.
Joe

Also, question @Nodge68 ?
Nodge mate,
I cannot see from rave if the LP pump in the engine bay can act as a one way valve or not. If it can, then the pressure (LP) from secondary LP pump should be maintained when off ?. Are you aware of if this is true or not ?.
Which begs the question - -- I am aware that both LP pumps will run with ignition on, but, if you were to pull the fuel pump relay, would the LP secondary pressure between LP and HP pump be maintained. ? (I hope that makes sense
The only way I can see pressure in the LP side between LP and HP pumps dropping when off or relay pulled is if the pump design will allow leakback or if the secondary LP pump pressure relief valve was allowing unwanted leak off. If the pump DOES normally allow secondary LP to HP depressurisation whilst ignition off then the question is academic lol.
If there is any uncertainty, then a test would be possible by turning ignition on, allowing secondary LP system to pressurise, then pulling relay and testing after time X.
any thoughts ?
Just pondering.
Joe

Ok I have run the tests
The fuel pressure readings when car left for 14 hours are low pressure 390 high pressure zero.
The same readings when car is up to 70 degrees was LP 360 and HP zero. Both readings go to LP 360 and HP 29k once car starts
I took car out monitoring the rising temperature to check restart ability.
First stop was at 37 degrees.turned off and car wouldn't restart
Next stop was at 50 degrees turned off and it restart but only just as was labouring. I immediately connected the rig and chose 80 degrees result no start. Then chose 30 degrees and result was strong restart
Next stop 62 degrees turned off and car it restarted. I then turned off and left it for 2 mins after which it till restarted, Same result again after 1 minute. Left it off for further 3 minutes and result no restart. I switched to rig and chose 30 degrees result was strong restart. changed to 57 degrees result no restart; changed to 70 degrees result no restart.finally changed down to 37 degrees result was strong restart.
Next stop 68 degrees at which point it easily restarts.Turned off and left car for 5 mins result restarted. Left further 2 minutes at which point temp was 65 degrees restarted.Left car for further 20 minutes temp 50 degrees no start

Hi mate,

What I note from the current tests is that I would have expected the HP pressure to be maintained when engine is off. ! - (LP certainly seems to be ok which answers one of my questions above re pressure holding in LP circuit). I would say that the Zero HP reading is abnormal. - looks (to me) like a HP pressure leak is occurring. (probably inside the pump at the pressure control valve / ball valve tank return - I would have thought the pressure regulator spring unit would have maintained a base pressure level even with power disconnected) - and your pressure drop off is rapid !- would be interested in @Nodge68 opinion on this - also - he can test on his for HP pressure maintenance. There are various valves in the pump and also the injectors themselves that should maintain HP. I believe you checked the injector leak back earlier hence it is indicative of pump leakback - All common rail systems should retain pressure. ! (Without further info to the contrary I would say that that is your problem and has been all along)

Nodge has the same vehicle and the same test unit (930) - I will await his comments as he is far more familiar with the TD4 and I trust his observations and experience.

There are other tests we 'could do' however I see no point in further tests until this is clarified.
Joe

Have you done a compression test on the cylinders?

Joe_H said:

Hi mate,

What I note from the current tests is that I would have expected the HP pressure to be maintained when engine is off. ! - (LP certainly seems to be ok which answers one of my questions above re pressure holding in LP circuit). I would say that the Zero HP reading is abnormal. - looks (to me) like a HP pressure leak is occurring. (probably inside the pump at the pressure control valve / ball valve tank return - I would have thought the pressure regulator spring unit would have maintained a base pressure level even with power disconnected) - and your pressure drop off is rapid !- would be interested in @Nodge68 opinion on this - also - he can test on his for HP pressure maintenance. There are various valves in the pump and also the injectors themselves that should maintain HP. I believe you checked the injector leak back earlier hence it is indicative of pump leakback - All common rail systems should retain pressure. ! (Without further info to the contrary I would say that that is your problem and has been all along)

Nodge has the same vehicle and the same test unit (930) - I will await his comments as he is far more familiar with the TD4 and I trust his observations and experience.

There are other tests we 'could do' however I see no point in further tests until this is clarified.
Joe

Click to expand...

Ok I tested my HP pressure this morning. I knew the figures I'd get, but tested anyway.
First test from cold, (16.6°C) engine NOT started, ignition ON. (Glow plugs not active)
LP 366Kpa dropping to 100.80Kpa after LP shutdown (about 1 minute)
HP 0.00Kpa (Synergy OFF)
(HP1024.68Kpa (Synergy ON) pulsing to 0.00Kpa every second or so.)
Engine running (idle)(Synergy OFF)
LP 346Kpa (slight fluctuation)
HP 26,600Kpa (slight fluctuation)

(Synergy ON HP 28,200)(slight fluctuation)


So in summary:
The LP pressure is only maintained while the LP pump is running.
HP pressure rail is only maintained while the engine is running.
What is interesting is the engine off LP pump off figures and the HP engine stopped figures.
After LP pump shut down the LP pressure drops to atmospheric pressure (100Kpa) with 0.8 inaccuracy.
The HP drops instantly 0.00Kpa. This to me indicates that the HP sensor could well be deactivated while the engine is stationery. If the sensor was to remain sensing, I would have expected to see 100Kpa or so. I would also expect to see 360Kpa while the LP pump is running.
There is another theory in my mind. That is that 100-360Kpa is below the sensors lowest pressure threshold.
I'll investigate the sensors pressure range, when I get a moment.
Hope this information is helpful?

I am so very conscious I have been commanding so much of your valuable time on this and would be happy to resort to a plan B workaround. .
Its obviously proving extremely difficult to pinpoint my precise fault. The only thing for sure is that my car seems to need more fuel at start up but copes fine once running.
I would like to take advantage of the coolant sensor default setting (triggered when disconnected) to override the starting issue but also want to switch back to normal once started. That way the control of cooling fans; needle position and true engine management is handed back to ECU.
Is it feasible that If I could run wires from the coolant sensor terminals to a dash mounted switch with wires leading back to sensor plug ? That way I could flick switch (to disconnect) before starting car and flick back once started..
It sounds like a fix to me but not sure if this would impact anything else. It will probably not be acceptable come MOT time
I appreciate correct route would always be to resolve the fault properly but what do you reckon to this as an alternative ?

Nodge68 said:

Ok I tested my HP pressure this morning. I knew the figures I'd get, but tested anyway.
First test from cold, (16.6°C) engine NOT started, ignition ON. (Glow plugs not active)
LP 366Kpa dropping to 100.80Kpa after LP shutdown (about 1 minute)
HP 0.00Kpa (Synergy OFF)
(HP1024.68Kpa (Synergy ON) pulsing to 0.00Kpa every second or so.)
Engine running (idle)(Synergy OFF)
LP 346Kpa (slight fluctuation)
HP 26,600Kpa (slight fluctuation)

(Synergy ON HP 28,200)(slight fluctuation)


So in summary:
The LP pressure is only maintained while the LP pump is running.
HP pressure rail is only maintained while the engine is running.
What is interesting is the engine off LP pump off figures and the HP engine stopped figures.
After LP pump shut down the LP pressure drops to atmospheric pressure (100Kpa) with 0.8 inaccuracy.
The HP drops instantly 0.00Kpa. This to me indicates that the HP sensor could well be deactivated while the engine is stationery. If the sensor was to remain sensing, I would have expected to see 100Kpa or so. I would also expect to see 360Kpa while the LP pump is running.
There is another theory in my mind. That is that 100-360Kpa is below the sensors lowest pressure threshold.
I'll investigate the sensors pressure range, when I get a moment.
Hope this information is helpful?

Click to expand...

Excellent info ! thanks Nodge ..
Hmmm, so the HP side DOES open to tank return on switch off. I am surprised, I would have thought the spring in the reg was strong enough to maintain some pressure. Obviously not intended to. - So, we know HP is dropped to atmospheric at ign off. Also, the LP does not block feedback as your tests prove. The pressure is only on the LP side when running - no residual.
As for the 100 - 360kpa on the Rail sensor. Yes, I would also have expected to see 100, however also, this is probably well below the registering range.
I wouldn't expect to see the LP side there though (the 360) as I can see no direct path from the LP vane side of the pump to the HP side (I dont believe the 3 plunger units have any pathway apart from LP to HP that is open to both at the same time (otherwise a situation could occur when the HP feed would be passed back to the LP Vane side) .
The key thing is though that the HP DOES drop off immediately at switch off and no residual pressure remains.

btw Nodge, just confirm where the synergy is plugged into - the HP rail sensor ?
Really appreciate the tests !
Joe

Ok Rednal, We now have accurate data re the HP side of the pump and it would appear normal.

That only leave one more test that we discussed earlier but never completed

Joe_H said:

Test - run car until the temperature actually DOES reach 70 or greater (with normal cts attached) and 930 monitoring.
Now, stop it and try and restart. Does it start ?
If not, then the window theory is wrong.
If it does, then now quickly connect the rig and set the temp to 50c (whilst the REAL engine temp is actually 70 C or more )
Does it start now at a manually set 50C with the rig ? note if it does start or not.
then drop the temp on the rig to 30C (with engine stopped)
Does it start now ? ?
This all needs to be done quickly so as not to let the engine cool below 70C (Actual temp!)

Whatever the results, now re-connect CTS and check the actual temp - note the temp and try and start. Does it start or not ?

Click to expand...

REDNAL3 said:

At 68 or above I can switch off and easily restart as many times as I wish. I guess at that temperature the cylinders are already so hot it doesn't take much to fire up.
Tomorrow I will get it up to 70c true temperature, introduce the rig and select a couple of lower temperatures.to see what effect it has.

Click to expand...

We need that one as well.
Joe.

REDNAL3 said:

I am so very conscious I have been commanding so much of your valuable time on this and would be happy to resort to a plan B workaround. .
Its obviously proving extremely difficult to pinpoint my precise fault. The only thing for sure is that my car seems to need more fuel at start up but copes fine once running.
I would like to take advantage of the coolant sensor default setting (triggered when disconnected) to override the starting issue but also want to switch back to normal once started. That way the control of cooling fans; needle position and true engine management is handed back to ECU.
Is it feasible that If I could run wires from the coolant sensor terminals to a dash mounted switch with wires leading back to sensor plug ? That way I could flick switch (to disconnect) before starting car and flick back once started..
It sounds like a fix to me but not sure if this would impact anything else. It will probably not be acceptable come MOT time
I appreciate correct route would always be to resolve the fault properly but what do you reckon to this as an alternative ?

Click to expand...

I think the ecu would go into default mode as soon as the cts was disconnected - and remain in that mode. - you can try it - start with plug disconnect and then plug back in when running - see if the MIL light and fans go off - I doubt it.

The final test at actual 70 + that I listed above is one that has been requested but overlooked. If it IS actually at 70 and you quickly add the test rig and lower the temps to 50 and then 30 and test the starting (whilst the actual is still > 70c ) the results will be informative.

There is a way we can add more resistance to the cts for the start and then remove it without disconnecting the sensor - it is a matter of testing though to see if the ecu sees a plausibility error when switching the added resistance out - it may well not.
For that you will need two fixed resistors and a small switch - from the two resistors we can select the best one. 3.9K and 4.7K (same physical size as the little one you got last time.

It will be like this - would have to test to see if we get a plausibility error (this would probably be ok, disconnecting the cts is unlikely to work.. but can be tried.

Ok nipped out and done those tests .
First test was plug switching whilst running. The ECU is fine with reattaching the coolant plug whilst running. It just shuts off the fan , warning light goes out and the needle goes to its true position,
Next test.. I ran the car up to true 73 degrees and the car restarted fine. I immediately attached the rig and chose setting of 42 degrees and it restarted fine I then chose setting 52 degrees with same result and same again at setting of 62 degrees. I then chose setting 100 degrees which triggered fan to come on but car wouldn't start. I reset it to 62 and it restarted fine and same for 52 degrees. Are these the results you anticipated ?

Joe_H said:

I think the ecu would go into default mode as soon as the cts was disconnected - and remain in that mode. - you can try it - start with plug disconnect and then plug back in when running - see if the MIL light and fans go off - I doubt it.

The final test at actual 70 + that I listed above is one that has been requested but overlooked. If it IS actually at 70 and you quickly add the test rig and lower the temps to 50 and then 30 and test the starting (whilst the actual is still > 70c ) the results will be informative.

There is a way we can add more resistance to the cts for the start and then remove it without disconnecting the sensor - it is a matter of testing though to see if the ecu sees a plausibility error when switching the added resistance out - it may well not.
For that you will need two fixed resistors and a small switch - from the two resistors we can select the best one. 3.9K and 4.7K (same physical size as the little one you got last time.

It will be like this - would have to test to see if we get a plausibility error (this would probably be ok, disconnecting the cts is unlikely to work.. but can be tried.
View attachment 105440

Click to expand...

Two things Joe.
There must be a fuel path from the LP to the HP as it's possible to see fuel at the leak back pipes while only the LP pump is running. Mine all leak back about 10mL in a minute. I know this because I tested it when I had that bout of misfiring a while back.

The Synergy plugs into two locations on the engine. There's a connection to the fuel rail sensor and another connection to the MAF sensor.
I also have a boost box fitted, this plugs into the MAP sensor.

REDNAL3 said:

Ok nipped out and done those tests .
First test was plug switching whilst running. The ECU is fine with reattaching the coolant plug whilst running. It just shuts off the fan , warning light goes out and the needle goes to its true position,
Next test.. I ran the car up to true 73 degrees and the car restarted fine. I immediately attached the rig and chose setting of 42 degrees and it restarted fine I then chose setting 52 degrees with same result and same again at setting of 62 degrees. I then chose setting 100 degrees which triggered fan to come on but car wouldn't start. I reset it to 62 and it restarted fine and same for 52 degrees. Are these the results you anticipated ?

Click to expand...

I hate to say it, but either your non starting is random, or I think it's an ECU fault.
However you plugging in the sensor while the engine is running has confirmed that you can rig a simple switch to force a start every time.