Disco 1 no spark

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HeavyPedal

New Member
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10
Location
Fergus, Ontario, Canada
I have a 1996 Disco 1 4 ltr V8 with no spark . Tests that I have done are as follows . At the ECU there is power to all the multi plugs . There is power to the ignition coil . The ignition coil was checked and they are good . There is power at the camshaft positioning sensor . The crankshaft positioning sensor has a ohms reading of 237 ohms . Athe crankshaft positionng senser there is a reading of 1.74 ac volts when engine is beeing cranked . The wires going to the crankshaft sensor have been repaired the wires where bare . Can anyone help me with my nightmare .:doh: The vehicle was missing before it stopped running and the ignition switch does not work right , you have to try 4-5 times before it turns over. but won't start.
 
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I think initially we need to establish which engine management system you have on the engine, before we start throwing ideas around.

It should be a Lucas system, but NAS vehicles had a mixture of devices.

The engine management system has to have a few things in place before it will enable the ignition, fuel pressure is one, so check the pump, the inertia switch on the firewall is another, but it shouldn't crank over if that is open, lastly the two sensors for camshaft and crankshaft have to be functional.

I'd start by checking fuel pump relay and fuel pump operation, then work your way through the other things.

Get a copy of the workshop manual, download from Green Oval or get a CD from ebay.

Report back what you find.

Peter
 
From the symptoms given and the info with it the car must be a NAS spec car which would have Gems injection/ignition system.
I cant remember what the resistance of the crank sensor should be but your reading sounds low.I always scope the crank sensor rather than trust resistance readings,and the ac voltage is totally dependant on engine speed so is of no help.
I have a spare crank sensor at work which I'll measure tomorrow.
 
Hi Eightinavee
the ohms reading that I gave you from the crank sensor , is from a brand new land Rover crank sencor that I have in there now . The only reason for the AC volts test was to make sure that I have a air gap for the sensor . and that it was working I did realize that the rpm will change the voltage readings . this tels me that this sensor is functual . The ECU is a ERR6759 GEMS 8 80674A
 
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listerdiesel said:
I think initially we need to establish which engine management system you have on the engine, before we start throwing ideas around.

It should be a Lucas system, but NAS vehicles had a mixture of devices.

The engine management system has to have a few things in place before it will enable the ignition, fuel pressure is one, so check the pump, the inertia switch on the firewall is another, but it shouldn't crank over if that is open, lastly the two sensors for camshaft and crankshaft have to be functional.

I'd start by checking fuel pump relay and fuel pump operation, then work your way through the other things.

Get a copy of the workshop manual, download from Green Oval or get a CD from ebay.

Report back what you find.

Peter
Click to expand...
Hi Peter
My ECU is a GEMS 8 the crank sensor is a new Land Rover one. The camshaft sensor I have no way of checking out the unit itself . I have power to it though I would think that this is a start. The rest that you mentioned to check I will get at that tomorrow and I will get back to you
 
Dont worry about the cam sensor,it only gives info for sequential injection to allow use of the knock sensors - it wont prevent it from running.
I dont have all the wiring diagrams for NAS spec cars,so I can only assume that it is similar to the v8 Defenders you had too.
My concern is that the engine ecu is not fully mobilised,your comments about the ignition switch and the engine not cranking are the reason for this. If its the same as the Defenders the alarm/immobilser ecu will send a coded square wave pulse to the Gems ecu when you key on.The Gems ecu will look at it and if its right will send back to the alarm ecu to allow cranking,sparks and fuel.This is the same as the P38 RR's where the check engine lamp comes on at key 2 to indicate the correct code has been received - does your car have a check engine lamp that works this way ? Some UK Disco's also have a passive immobilisation coil around the ignition switch which energises when you put the key in to read the transponder chip in the key fob - again,not sure if you have these features,but they would all give the same problems if it does.
My spare,("Known good") crank sensor reads 840 ohms,but I wouldnt worry too much about that for now.
You say there is no spark when cranking - is there any fuel being injected when there is no spark ? Does your car have an emergency key access code - if it does it may be worth entering this before you try cranking,cheers Jon.
 
Hi Eightinavee

after the engine stopped I started doing the normal little checks . Of course I found nothing . I then removed the ECU and I found the bottom had rotted out . Seeing this I bought a good used ECU with all the same numbers as the old ECU . I,m thinking now , will I have to get the codes reset . As far as fuel goes I found out tonight that the fuel rails have no pressure in them . I went to the fuel pump and found no power when the key was first turned on . I believe that there is a five or six second running time of the pump when the ignition is turned on , it will pressurize the fuel system before starting, . The fuel pump has to be changed now because the metal lines going out of it are all rotten. I never checked the fuel pump but just guessing it does not work . That is job to check tomorrow .
 
The replacement ecu will need a relearn on Testbook before the car will start,sounds like you are on the right road to fixing it.
 
Hi eightinavee
thanks for the further information that you gave me . I mentioner that I had no fuel pressure and thought it might be the pump . I tested the pump and it tested out ok the sending unit is not . I replaced the fuel pump relay and the pump works again . Well that one thing fixed and more to go
 
Hi eightinavee
I was going over one of the past replies and you asked if I have a passive immobilization coil around the ignition switch . not sure how do I find out .You mentioned a alarm/immobilizer ecu from what I understand if the alarm ecu is working right it will send a signal to the main ecu (with the three large multi plugs) to allow fuel spark and cranking. I replaced the fuel pump relay and now I have fuel .I have cranking if I try 4 or 5 times . The engine will crank every time if I don't turn the ignition switch to the off position before trying to start . I do not have spark .I do have a check engine light , when the key is turned on the light will stay on for about 7 sec. then go out . You mentioned are the injectors giving fuel when turning over with no spark . How can I check that . Should I take a volt reading at the injector multi plug when cranking if so what should the voltage be .Last but not least emergency key access code where can I find it and how will I use it
 
HeavyPedal said:
Hi eightinavee
I was going over one of the past replies and you asked if I have a passive immobilization coil around the ignition switch . not sure how do I find out .You mentioned a alarm/immobilizer ecu from what I understand if the alarm ecu is working right it will send a signal to the main ecu (with the three large multi plugs) to allow fuel spark and cranking. I replaced the fuel pump relay and now I have fuel .I have cranking if I try 4 or 5 times . The engine will crank every time if I don't turn the ignition switch to the off position before trying to start . I do not have spark .I do have a check engine light , when the key is turned on the light will stay on for about 7 sec. then go out . You mentioned are the injectors giving fuel when turning over with no spark . How can I check that . Should I take a volt reading at the injector multi plug when cranking if so what should the voltage be .Last but not least emergency key access code where can I find it and how will I use it
Click to expand...
My problem is the lack of NAS spec cars in this country - I simply dont know what kit/setup they were built with.The passive ring is a coil of wire in a (Usually) black plastic housing which is fitted around the ignition lock barrel.It does sound like its mobilised as its cranking - but the 4 or 5 turns of the key are a worry.Especially as you say it will crank every time as long as you dont key off.This is what makes me think its an immobiliser fault,but you are going to need the exact wiring diagram for your car to work through it.
With the ignition on there will be 12 volts across the injectors,the ecu drops one side down to 0v to fire the injectors ,so a multimeter should be quick enough at cranking speed to see if they are injecting.
An oscilliscope is the best way to see what the crank sensor is doing - then you will know if the ecu is getting a signal good enough to use,if it is then you have to look at why there is no spark.
On UK spec Gems equipped RR's the check engine lamp stays on till the engine starts,but again I have no experience of NAS cars.
Would it be worth asking some of these questions on a US based LR forum for better local knowledge ? Or can you post up the wiring diagram if you have it ?
 
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