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Faulty Diagnosis

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Browndoff
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Joined: 22 Mar 2013
Posts: 513
Location: Dublin 13, Ireland

PostPosted: Tue Jul 16, 2019 17:21    Post subject: Faulty Diagnosis Reply with quote

HELP!!!!!

I'm going crazy [well, more crazy!]. I've been having a 'reliability' problem for quite a while with my 3.0L LWB - sudden cut-out [will restart], sometimes hard to start, sometimes starts but won't answer the throttle AT ALL! Recently had to take it for NCT and it actually stopped during the test! A really kind tester guessed it was an intermittent fault, so he allowed me to juggle the THROTTLE cables and re-start it - bless his heart! Since then it started only once and 'hunted' horribly between 550 and 650 RPM - would NOT rev up and then died-out.

So, I replaced the TPS and, assuming the ORPS was 'dying' too, replaced that today. Rebuilding the engine, I expected it to take ages to generate enough oil-pressure to start but, NO, it started after a total of 20 seconds of turning-over. It ran VERY smoothly at about 700 RPM [at least 10 minutes] but ignored the throttle completely. I stopped it and it restarted immediately - no throttle response.

I read page after page of advice given to members who had a problem with the ORPS and MANY of the symptoms seemed to fit my Trooper - so I was convinced that replacing the ORPS would solve all my problems. Now it will start quickly but NOT REV UP.

My basic diagnosis must have been wrong - or, at least, did NOT cover ALL its faults - HELP!!
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2002 LWB Trooper 3.0L
I've done some major repairs, including replacing half-shaft, replacing fuel-injectors etc.
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pighauler
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Joined: 10 May 2019
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Location: lincolnshire

PostPosted: Wed Jul 17, 2019 17:42    Post subject: Reply with quote

That sounds a bit like the symptons I had when the pick up pipe snapped the bracket and dropped into the sump, might be worth putting the extra 2 ltrs of oil in the engine to overfill the sump to test
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wildata
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Joined: 19 Feb 2009
Posts: 104
Location: Ireland

PostPosted: Thu Jul 18, 2019 9:05    Post subject: Reply with quote

Hi
Would agree with Pighauler, definitely try + 2 litres of oil.

Wildata.
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Browndoff
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Joined: 22 Mar 2013
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Location: Dublin 13, Ireland

PostPosted: Thu Jul 18, 2019 23:41    Post subject: Reply with quote

Thanks for the replies!

Really, though, it's now starting first turn of the key and running smoothly at about 700 RPM. I left it running at tickover for over 10 minutes - no problem and it restarted immediately when I tried it. It would hardly do that if it wasn't reaching adequate pressure in the oil-rail....?

The current ongoing problem is NO RESPONSE AT ALL to the throttle. Literally - there's no change in RPM, no change in engine sound - nothing AT ALL! I'm worried that there might be an electrical fault in the Fly-By-Wire system.....?
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2002 LWB Trooper 3.0L
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Mike Rosie
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Joined: 16 Nov 2005
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PostPosted: Sat Jul 20, 2019 8:28    Post subject: Reply with quote

check out the accelerator pedal sensor and associated wiring back to the ECU.
Have you got a tech 2
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Browndoff
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Joined: 22 Mar 2013
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Location: Dublin 13, Ireland

PostPosted: Sat Jul 20, 2019 22:49    Post subject: Reply with quote

Thanks, Mike Rosie!
I Think you're right. Today I took off the Accel Pedal Assy and tried to check the output voltage on the signal wire [white]. Zero - and it didn't change when I moved the pedal! Removed the sensor and reconnected it to the control-circuit. Then I COULD get a variable output-voltage!

But - most importantly - when I started the engine, it ran smoothly at about 700 RPM - but though the sensor-actuator was being turned by hand, it had NO EFFECT on the engine!

There MUST be a fault in the loom between the Pedal and the ECU - or, horror of horrors, within the ECU itself. I really hate electrical wiring problems!!
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I've done some major repairs, including replacing half-shaft, replacing fuel-injectors etc.
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Mike Rosie
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PostPosted: Sun Jul 21, 2019 7:24    Post subject: Reply with quote

I had a temperature input on an ECU fail before, it was the oil rail one.
It ran with a fault but I had to replace the ECU in the end,with a secondhand unit.
If you go down this route mind and get a complete ecu/keys/imobilisher package.
Hopefully it’s something else.

Mike
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Browndoff
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Joined: 22 Mar 2013
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Location: Dublin 13, Ireland

PostPosted: Mon Jul 22, 2019 17:19    Post subject: Reply with quote

I'm concerned that there MIGHT be a dodgy link in the wiring-loom - but today I got a clear solid link from the Accel-Pedal-Sensor back to the ECU - WHILE the engine was running. The three major connectors were connected to the ECU and the two connectors were connected to the AP-Sensor [though it was detached from the pedal assembly].

So, I was able to get the steady 5V from AP-1 [red] and variable voltage [when I moved the AP-Sensor] from AP-2 [white] AND from the other end of the white wire at J2-25 at the ECU. That variable voltage is supposed to rev up the engine - but it had NO EFFECT.

Why didn't it rev up the engine? I thought that was all that the 'Fly-by-Wire' system needed....?
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2002 LWB Trooper 3.0L
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Mike Rosie
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PostPosted: Mon Jul 22, 2019 22:15    Post subject: Reply with quote

It may unfortunately be that the ecu input has failed like it did with my temperature input.
If you can get a tech 2 on to it you should be able to see exactly what’s going on
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Mike Rosie
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Joined: 16 Nov 2005
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PostPosted: Mon Jul 22, 2019 22:20    Post subject: Reply with quote

Just checked my old post and when I had my issue I had no 5 volts supply to sensor, so that’s a bit different to you.
You really need a tech 2
Mike
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Browndoff
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Joined: 22 Mar 2013
Posts: 513
Location: Dublin 13, Ireland

PostPosted: Tue Jul 23, 2019 15:45    Post subject: Reply with quote

Thanks again, Mike! No Tech-2 at present - I'll have to test the circuits individually.....

A friend [a GREAT mechanic - but NOT a Trooper expert] suggested that my 4JX1 might be 'SET' on IDLE by a fault in the loom or the secondary unit within the AP-Sensor, which is the Idle-Switch.

According to the Manual's wiring diagram on 6E-75 [p1968], a green/red wire is linked to the ECU at J2-8 [12V?] and the second wire [same colour?] is directly linked to EARTH. It seems that the J2-8 should be a LIVE wire when the Accelerator-Pedal is 'untouched' and ZERO volts when the driver moves the pedal. When the sensor is moved with the engine running, clearly it should speed-up the engine - but if the Idle-Switch is meant to be a safeguard against a 'runaway' engine - maybe it COULD prevent the sensor-movement from accelerating the engine if it was wrongly earthing [or NOT] the J2-8 lead in the ECU....?

Anyway, today I plan to check out the electrical connections to the Idle-Switch and whether, or not, it's behaving as intended.
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2002 LWB Trooper 3.0L
I've done some major repairs, including replacing half-shaft, replacing fuel-injectors etc.
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Browndoff
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Joined: 22 Mar 2013
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Location: Dublin 13, Ireland

PostPosted: Tue Jul 23, 2019 17:50    Post subject: Reply with quote

Does the Idle-Switch over-ride the Accelerator? I.E. if the Idle-Switch is NOT reacting properly to movement of the AP-Sensor, it might keep the engine at tickover despite the pedal being pressed…? The Wiring Diagram at 6E-75 [p1968] shows that the Idle-Switch [on the AP-Sensor] is connected by a green/red wire to J2-8 and by a black wire [with a green spot?] to earth.

With ignition ON and the Idle-Switch lead disconnected from the Accel-Pedal-Sensor, the ECU terminal J2-8 shows 12.08V [current full battery voltage]. When it’s connected, J2-8 shows about 0.25V – which shows that the Switch is CLOSED to earth when the accelerator pedal is untouched. When it’s connected AND the sensor is moved, J2-8 shows 12.08V again – which shows that pedal movement OPENS the Idle-Switch. With the engine RUNNING, J2-8 shows 0.3V with the pedal untouched and 13.6V [generator Voltage] when the sensor is moved – but on my Trooper this movement DOES NOT affect the engine speed! Something ELSE is still wrong with the engine-control system!
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2002 LWB Trooper 3.0L
I've done some major repairs, including replacing half-shaft, replacing fuel-injectors etc.
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Browndoff
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Joined: 22 Mar 2013
Posts: 513
Location: Dublin 13, Ireland

PostPosted: Wed Jul 24, 2019 11:22    Post subject: Reply with quote

My dear friends - I have to apologise - the problem since the replacement of the ORPS WAS ALL MY OWN FAULT!!

I remembered that I had disconnected some cables [just for ease of access] when I was changing the ORPS – what if I had NOT reconnected them PROPERLY????

So – I pulled the plug out of the MAP-sensor and re-inserted it, jiggled the cables attached to the ROPCV and made sure no other connection was visibly loose ….. then I restarted the engine and moved the AP-sensor – the bloody engine revved-up immediately – as if the problems had all been in my imagination!!

I re-assembled the Accelerator Pedal unit and took the beastie for a spin - perfick! Happy Days!!!

Thanks again to the patient help of ITOCUK forum members!!
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I've done some major repairs, including replacing half-shaft, replacing fuel-injectors etc.
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Mike Rosie
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PostPosted: Wed Jul 24, 2019 21:58    Post subject: Reply with quote

Yep done that sort of thing before.
Good that it’s sorted and was an easy fix.
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Browndoff
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Joined: 22 Mar 2013
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Location: Dublin 13, Ireland

PostPosted: Thu Jul 25, 2019 12:45    Post subject: Reply with quote

Thanks again, Mike!

The real worry is that this could happen to ANYBODY! Without any sensor or 'important' part of the vehicle going faulty - an owner can be plagued by serious fault symptoms - which are actually just due to the old age of our vehicles!

Loose connectors [making poor electrical contact], hardened old cables breaking inside the insulation etc. - producing 'proof' that some part has become faulty - when in fact it's just ACCIDENTALLY disconnected!
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I've done some major repairs, including replacing half-shaft, replacing fuel-injectors etc.
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