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Thread: Honeymoon's over

  1. #1
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    Honeymoon's over

    Well, it was too good to be true.

    First time I've been let down by the Rangie, and it's a doozy.

    Almost a month ago I drove up

    A tow from Brandon, just north of Ayr to the Tablelands ($2Ktow on a sunday )

    It's an Electrical gremlin of some kind. AND Random.
    Possibly a failure due to thermal cycling or moisture related.

    firstly: When the issue occurs-

    engine cranks no prob. fuel pump primes, rail pressure is bled off (can hear the regulator) but-
    1. No spark.
    2. It's intermittent - will crank, fire up and run one day, then simply won't go the next.
    3. New: Coil, module, Dizzy, rotor(s) cap(s). multiple replacements only because all my tools are still in a container somewhere and should have been here 3 weeks ago.

    Definitely have power to the ignition coil.

    Dizzy gives output from the reluctor. Module tests oK (both do).

    Caps and rotors made zero difference (was first cab off the rank replaced after the tow home)

    Got a Disco dizzy from a nice bloke in Cairns to test the failed reluctor theory - but after purchasing a cheapo jaycar multimeter (local hardware happens to be a jaycar agent - yay) it tested OK for pulse generation and the dizzy modules also tested OK.

    I have 2 known good caps/rotors plus the one on the car is proving to be reliable and no combination or replacement of either cap or rotor or both proves to make any difference to the outcome.

    Relays have been checked (under drivers seat) as have fuses inertia switch operation etc.

    Don't have a schematic or ETM available to me at the moment to commence fault trace, and I suspect that there is a sensor failure or possibly the MAF - but would need test values to determine if it is OK.

    Worst of all this is totally random - and the car will literally just fire up without any intervention, but it will also fail to start after driving the previous day.

    Fuel's fine - and pressure is there. Pump was replaced back in 2015 and it's never given any grief (and you can hear it prime and delivers pressure to the rail
    Weather makes no difference (car is undercover)

    Need to take a step back and look into the ecu operational requirements and if there is something preventing it from starting and what that component failure mode is.
    Roads?.. Where we're going, we don't need roads...

  2. #2
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    Quote Originally Posted by Mercguy View Post
    Well, it was too good to be true.

    First time I've been let down by the Rangie, and it's a doozy.

    Almost a month ago I drove up

    A tow from Brandon, just north of Ayr to the Tablelands ($2Ktow on a sunday )

    It's an Electrical gremlin of some kind. AND Random.
    Possibly a failure due to thermal cycling or moisture related.

    firstly: When the issue occurs-

    engine cranks no prob. fuel pump primes, rail pressure is bled off (can hear the regulator) but-
    1. No spark.
    2. It's intermittent - will crank, fire up and run one day, then simply won't go the next.
    3. New: Coil, module, Dizzy, rotor(s) cap(s). multiple replacements only because all my tools are still in a container somewhere and should have been here 3 weeks ago.

    Definitely have power to the ignition coil.

    Dizzy gives output from the reluctor. Module tests oK (both do).

    Caps and rotors made zero difference (was first cab off the rank replaced after the tow home)

    Got a Disco dizzy from a nice bloke in Cairns to test the failed reluctor theory - but after purchasing a cheapo jaycar multimeter (local hardware happens to be a jaycar agent - yay) it tested OK for pulse generation and the dizzy modules also tested OK.

    I have 2 known good caps/rotors plus the one on the car is proving to be reliable and no combination or replacement of either cap or rotor or both proves to make any difference to the outcome.

    Relays have been checked (under drivers seat) as have fuses inertia switch operation etc.

    Don't have a schematic or ETM available to me at the moment to commence fault trace, and I suspect that there is a sensor failure or possibly the MAF - but would need test values to determine if it is OK.

    Worst of all this is totally random - and the car will literally just fire up without any intervention, but it will also fail to start after driving the previous day.

    Fuel's fine - and pressure is there. Pump was replaced back in 2015 and it's never given any grief (and you can hear it prime and delivers pressure to the rail
    Weather makes no difference (car is undercover)

    Need to take a step back and look into the ecu operational requirements and if there is something preventing it from starting and what that component failure mode is.
    You must have a wiring issue somewhere in the coil circuit. try pulling and cleaning all the fuses .... then hope the thing stays broken so you can find where the wiring issue is (its very hard to find a wiring issue that is intermitant). Now, I just need to find some time to look at the ****box here for exactly the same checks .....
    Proper cars--
    '92 Range Rover 3.8V8 ... 5spd manual
    '85 Series II CX2500 GTi Turbo I :burnrubber:
    '63 ID19 x 2 :wheelchair:
    '72 DS21 ie 5spd pallas
    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual :zzz:
    '11 Poogoe RCZ HDI 6spd manual

  3. #3
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    So I did a bit of ham-fisted diagnostics yesterday after slashing... I was tired, but not making excuses. Following outcomes.

    Coil has 13.2-13.8v with ign on
    coil has 0v (yep ZERO) when cranking. as in zip, nada, zilch.

    I tested coil+ and coil - direct from battery, and pulled the coil lead from dizzy, attached a spare sparkplug and let it earth out to the block for confirmation.

    No spark.

    Fuels fine, cranks beautifully.
    Have had to disconnect the ecu sensor wire to do some tests, but it's obviously connected when trying to start the thing.

    I have returned the original dizzy, rotor, cap and module, but left the new coil in situ, as it's a PITA to R&R coils (and they are both good units, so can stay until I find the culprit.

    All fuses inline with IGN have been checked (c3, c4) and no issues.

    Lastly, I removed lower dash cowl and steering column cowl to check the ignition switch (which I replaced back in 2015) - it is fine physically, but I have not tested it electrically yet (ran out of daylight)

    Does anyone have values for the MAF that I can test either in standalone or inline? and also are there any other dependencies in the circuit which would pull the coil down to 0v when cranking if there is a failed sensor or other conditions.

    EDIT: Have tested MAF - it's sitting on 0.41v with ign on and the heater circuit has approx 12.5v with ign on, then drops to around 10.8-11 when cranking. So MAF=OK.

    This old bus has been absolutely reliable until this point, it's now been sitting a month and I'm seriously contemplating pulling it onto the other paddock with the tractor and letting it roll down the hill, possibly set ablaze.

    If people want a parts car, now might be a good time to hit me up.

    Lastly - anywhere on the passenger side that could contribute? i.e. is there a harness connector that I may not be aware of or something else I need to look for.

    Not in the right frame of mind to be calm about troubleshooting right now.... I'm preoccupied with visions of a flaming RRC rolling down a hill and then exploding like the mythbusters cement truck.
    Roads?.. Where we're going, we don't need roads...

  4. #4
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    Hi,
    I recently had a problem with my RR and when you mentioned the power was dropping out at the coil when cranking the engine it reminded me of my problem and the reason why it was not playing the game.
    I had the problem for months and was over thinking the cause.
    When cranked to start the engine the starter motor would semi engage and make it sound like the starter was at fault and on a really hot day it would not crank over at all.
    I eventually found the problem, after purchasing a new starter.
    It all came down to dirty battery terminals, once given a good bit of maintenance all was fine and have had no problems since.
    The problem of course was that the terminals were not allowing enough power from the battery to the starter so the starter, when being engaged, sucked all the available power away from everything else in order to operate the starter which would mean maybe in your case the coil has no power to it.
    I'm not trying to say that that is definitely what you problem is but I just thought it would not hurt to give the terminals a good scrub up. You never know.

    Regards:-
    Patrick M

  5. #5
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    Understood. It's sage advice for anyone / everyone actually. make sure all connections are clean and contact is solid.

    fwiw, I run 000 B&S direct to the starter from the battery and there are multiple earth straps to chassis, engine and ironically, to the side of the coil bracket. All are clean, properly crimped and soldered ends, heatshrink protected with lanolin grease and wire gauge is er... overkill size. My charge cable from the alternator to the battery is a 75mm sq. high temp ultraflex and the main feeds into the cabin are all 00 B&S.
    There is a 0000 B&S cable connecting start battery to the aux battery via 200A cont. solenoid, for winching or jump starting or any time high current is needed at the push of a button.

    So generally speaking, the electricals which have been replaced are done properly with appropriately sourced components.

    This issue however, is the consequence of a decision I made back in 2015 to not get rid of the prince of darkness completely.
    What I should have done back then is tossed the 14cux for an aftermarket ECU and rewired it from scratch. But That was then. I chose to save pennies and fix the necessary. At the time, the only issue I had was related to previous owner butchery of the harness, through alarm, aftermarket cruise and radio installations, as well as the obligatory 'patch cables' in the engine bay from degraded or failed wiring.
    There is still some original harness there in the engine bay, notably the injector harness and the temp, oil, fuel senders and the tach wire for alternator and MAF harness (which ironically connects to the coil)

    For me, it is relatively safe to discount the portion of electrics that I have replaced. There are some unknowns still in the vehicle, and obviously one of those is behind the issue.
    Without my tools here yet, it makes it hard. cheapo multimeter with unconventionally short test leats doesn't help, but I'm not going to buy a decent dmm up here in the sticks. I can test in iso, but that's about it due to short leads. so now I need to chase the prince fo darkness and his connectors through the body and see where I end up.

    I'm still liking the sound of fire in the hole followed by a ball of fire accompanying a loud bang.
    Roads?.. Where we're going, we don't need roads...

  6. #6
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    Well you have found the problem. 0volts at the coil when cranking means it will never start. Who wants to bet you have the identical issue to me .... SO if I just wait a bit, you will solve it for me

    Seriously, we need to hit the wiring diagrams. There is obviously a 'start' and 'run' circuit. Possibly through the key. We need to trace out the start circuit and see where the problem in it is. Even really early cars had a "start" circuit to bypass the ballast resister and throw 12volts at the coil for easy starting.
    Proper cars--
    '92 Range Rover 3.8V8 ... 5spd manual
    '85 Series II CX2500 GTi Turbo I :burnrubber:
    '63 ID19 x 2 :wheelchair:
    '72 DS21 ie 5spd pallas
    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual :zzz:
    '11 Poogoe RCZ HDI 6spd manual

  7. #7
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    Quote Originally Posted by DoubleChevron View Post
    Well you have found the problem. 0volts at the coil when cranking means it will never start. Who wants to bet you have the identical issue to me .... SO if I just wait a bit, you will solve it for me Seriously, we need to hit the wiring diagrams. There is obviously a 'start' and 'run' circuit. Possibly through the key. We need to trace out the start circuit and see where the problem in it is. Even really early cars had a "start" circuit to bypass the ballast resister and throw 12volts at the coil for easy starting.
    Given there are around 25 years of the RRC, it would be interesting to know which one we are talking about.
    ​JayTee

    Nullus Anxietus

    ​Getting involved in discussions is the best way to learn.

    2000 D2 TD5 Auto: Tins
    1994 D1 300TDi Manual: Dave
    1980 SIII Petrol Tray: Doris
    OKApotamus #74
    Nanocom, D2 TD5 only.

  8. #8
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    Quote Originally Posted by Tins View Post
    Given there are around 25 years of the RRC, it would be interesting to know which one we are talking about.
    Oh I didn't mean just range rovers. There are all sorts of weird and wonderful wiring setups on older cars. allowing some to start and not run once you release the key .... or run, but not start etc..... depending on how they wire any ballast resistors. Even my '85 car has a tachometric relays, so still two different circuits for start and run. One circuit allows the fuel pump to run when the key is held in the "start" position, but drops out and senses the tach pulse once the key is released back to run.

    without the wiring diagrams.... it sure would be fun to sort the mess out!
    Proper cars--
    '92 Range Rover 3.8V8 ... 5spd manual
    '85 Series II CX2500 GTi Turbo I :burnrubber:
    '63 ID19 x 2 :wheelchair:
    '72 DS21 ie 5spd pallas
    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual :zzz:
    '11 Poogoe RCZ HDI 6spd manual

  9. #9
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    Quote Originally Posted by DoubleChevron View Post
    Oh I didn't mean just range rovers. There are all sorts of weird and wonderful wiring setups on older cars. allowing some to start and not run once you release the key .... or run, but not start etc..... depending on how they wire any ballast resistors. Even my '85 car has a tachometric relays, so still two different circuits for start and run. One circuit allows the fuel pump to run when the key is held in the "start" position, but drops out and senses the tach pulse once the key is released back to run.without the wiring diagrams.... it sure would be fun to sort the mess out!
    Oh, I get it... Owned a few 'odd' cars in my time. In this case though, I have wiring diags for the '95, but it would be a waste of time if they aren't for the one being discussed.
    ​JayTee

    Nullus Anxietus

    ​Getting involved in discussions is the best way to learn.

    2000 D2 TD5 Auto: Tins
    1994 D1 300TDi Manual: Dave
    1980 SIII Petrol Tray: Doris
    OKApotamus #74
    Nanocom, D2 TD5 only.

  10. #10
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    Where are you based mate?

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