Land Rover Discovery 1 V8i 3,9 L EFI doesn´t start

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T

Trotti

Member
Posts
17
Location
Germany
Hello together,

I´m driving a Land Rover Discovery 1 from 1998. It has the 3,9 L V8i EFI. The ECU is the 14cux and the car has two lambda sensors and a cat.
The story began last summer in the south of France. It was my first vacation with the Disco and we drove 1000+ km without any problems. Then we wanted to drive on the Col du Parpaillon and after a short stop before the track, the car suddenly didn´t start again. When you crank the engine, there is no firing, but you can smell fuel.
Back home we checked the car with RoverGauge, but there was no fault code. After this we checked all eight spark plugs. They are in a condition as good as new, but we exchanged the Lucas ignition amplifier. The distributor and the ignition wires are looking good and the wiring is correct. With RoverGauge, we could see that the fuel pump is running, we could hear it clearly and the fuel pressure on the fuel rail is 2,5 bar, just like the workshop manuel says. Before the trip we already changed both lambda sensors.

Now my question. Has anyone an idea why the Disco doesn´t start again?

Thank you for your help!

Leo from Germany
 
If as the UK D1 your vehicle is fitted with an immobiliser then there may be an a issue with it.
So with a length of wire simply link the battery + to the ignition coil + ( to ID the + terminal a black wire is connected to it) then go and crank the engine,
 
I had this on classic RR started fine cold but just wouldn't work if tried to restart after short stop. Hour later started as there was nothing wrong. It turned ot to be the "ignition relay" it came on but wouldn't pass any heavy current. This gradually got worse, when it failed completely I found it. Massive inconvenience for a £2.50
 
Thanks for your tip @discool, i will try it tomorrow directly. Do you think about the `Spider´?

@PaulJM I could not find an ignition relay in the workshop manual. Where is it located in your RRC?
 
On yours I believe it is the lefthand relay at the bottom behind the righthand trim panel between door and pedals. In landrover Rave manual it is called ignition load relay K127
 
Trotti said:
Thanks for your tip @discool, i will try it tomorrow directly. Do you think about the `Spider´?

@PaulJM I could not find an ignition relay in the workshop manual. Where is it located in your RRC?
Click to expand...
Thats because you don't have a relay with that title. Its not a RRc.

On your DI theres a relay K137 called “starter relay” sometimes called “starter solenoid relay” on a RHD disco the relay is in the drivers footwell and on the lower level and is in the center one of three relays, and it has a yellow cap.
One one side of the starter relay is the ignition load relay controlling the AC blower or air recirculating solenoid, again its with a yellow cap, on the other side is the front wiper relay with a green cap… of course thats when the disco left the factory :)

As you state your engine cranks then there’s not an issue with the starter relay.
 
@discool I'm still wondering why there is a problem with the ignition coil when there is spark on every spark plug. Is the spark then too small or not strong enough to ignite?
 
Trotti said:
@discool I'm still wondering why there is a problem with the ignition coil when there is spark on every spark plug. Is the spark then too small or not strong enough to ignite?
Click to expand...
Yes. You can have a visible spark but it's too weak. A weak spark has a yellowish hue and a strong spark is is bright white, especially if you can view them in low light.
 
Trotti said:
@discool I'm still wondering why there is a problem with the ignition coil when there is spark on every spark plug. Is the spark then too small or not strong enough to i
Click to expand...

i’ve known a coil to fail, luckily only once and that was wile rolling a long at 30mph and the engine just cut out, so left the car there by the roadside and walked home, purchased a replacement coil next day and fitted it, the car started straight away, job done.
The old coil was tested and I found there was no continuity across the terminals confirming a complete failure.
All that was before my LR days starting in 1987.

With the immobiliser issue, something similar happened around six years ago, and with a weak spark as my investigation later found out, although I had six months previous warning with the engine failing to restart and then restarting after five minutes or so, one time was disembarking on a cross channel ferry and it wouldn’t start but then restarted and was brilliant for the rest of the day.

But then that immobiliser circuit finally failed so requiring a flatbed to take the disco and me home where I now did a voltage test at the coil and found voltage at the coil a lot lower than the 12v plus…hence the poor spark.
So fixed the issue and disco has been ok since :)
 
discool said:
i’ve known a coil to fail, luckily only once and that was wile rolling a long at 30mph and the engine just cut out, so left the car there by the roadside and walked home, purchased a replacement coil next day and fitted it, the car started straight away, job done.
The old coil was tested and I found there was no continuity across the terminals confirming a complete failure.
All that was before my LR days starting in 1987.

With the immobiliser issue, something similar happened around six years ago, and with a weak spark as my investigation later found out, although I had six months previous warning with the engine failing to restart and then restarting after five minutes or so, one time was disembarking on a cross channel ferry and it wouldn’t start but then restarted and was brilliant for the rest of the day.

But then that immobiliser circuit finally failed so requiring a flatbed to take the disco and me home where I now did a voltage test at the coil and found voltage at the coil a lot lower than the 12v plus…hence the poor spark.
So fixed the issue and disco has been ok since :)
Click to expand...
On my RRC it was a bad coil that caused the weak spark.
 
Hello again, I just connected the battery + to the ignition coil +. When I tried to start the engine, nothing happened, except that the ignition was on all the time, even if the key was not inserted. I could hear an ignition twice but the engine did not start. Is there any way I can easily check the ignition coil or do you have another idea?

Leo
 
Trotti said:
Hello again, I just connected the battery + to the ignition coil +. When I tried to start the engine, nothing happened, except that the ignition was on all the time, even if the key was not inserted. I could hear an ignition twice but the engine did not start. Is there any way I can easily check the ignition coil or do you have another idea?

Leo
Click to expand...
When I had this problem years ago I Googled it and found some info and videos on the process using a voltmeter but I can't remember the process.
Coils aren't expensive. You could just get a new one.
 
Trotti said:
Hello again, I just connected the battery + to the ignition coil +. When I tried to start the engine, nothing happened, except that the ignition was on all the time, even if the key was not inserted. I could hear an ignition twice but the engine did not start. Is there any way I can easily check the ignition coil or do you have another idea?

Leo
Click to expand...
Ok you did said the engine cranks, providing a direct 12v supply to the coil wouldn't stop cranking, also the ignition should be on with out, no idea but remove the black wire from the coil + and try again.
But there's no need if you have 12v at the coil +.
The wire link is just taking the pace of the black wire when the ignition switch is on position two so providing 12v to the coil and then only if the engine has been re-mobilised .by the spider..

Below is a copy of the page from the Haynes manual on testing the coil and the ignition..
And upside down :mad: at the moment i don’t know why the office scanner is mis behaving. :(
 

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Thanks for the picture Haynes manual. I will test the ignition coil the next few days, but at the moment I do not have access to the Disco
 
Good evening, today I checked the ignition coil and it looked ok. So I continued looking for the pick-up coil, which was also ok. Last but not least, I compared the timing marks on the crankshaft pulley and the position of the pick-up coil. When the first cylinder was at TDC, the pick-up coil also pointed to the port of the first cylinder.

My thougts now are, that the timing between the injectors and the ignition spark is not correct, because when you try to start the engine with starter spray it also does not start. So my next question is how does the ECU know when to supply fuel to the correct cylinder?
Greetings from Germany
 
Hi looking at the circuit diagram for ECU a feed appears to come from the ECU (MFI) to the coil and pulses from the distributer will be sensed from there. There are no crank shaft or camshaft sensors.
 
Trotti said:
My thougts now are, that the timing between the injectors and the ignition spark is not correct, because when you try to start the engine with starter spray it also does not start.
Click to expand...

Way off track there.

1) the injectors timing is not relevant - they are in fact not "timed" at all and fire in 2 batches based entirely on the spark timing signal to the ECU. When starting it fires both batches together, then moves to alternating firing. The first batch-fired side isn't even the same side, relative to engine timing each start - it's based entirely on the first spark signal the ECU sees and it never knows which cylinder is firing anyway.

2) If it doesn't fire or cough with easy spray, there is NO point in even looking at the fuel system - you either have an ignition or compression issue (more likely ignition, because easy spray should at least make a pop!)


SO, to be clear: you're saying it just cranks and cranks, without any pops, bangs, coughs, nothing - just smooth cranking?

You need to do the basics properly, then move on from there.

Compression test. This could show several issues that could cause no starting.

Check for cranking RPM in Rovergauge while cranking (this shows the spark trigger system and the reading to the ECU working, though doesn't guarantee actual spark).

Check for spark at the coil wire to the distributor, if present THEN to each plug. You can get an in-line spark tester, so you can SEE the spark, while it's firing the plug in the cylinder. If you aren't getting backfires, pops, bangs or coughs, chances are there is no spark in the cylinders - otherwise the easy start would at least cause a noise. You could also use an inductive timing light on lead one and see if the light is triggered... and you could also check the actual timing at the same time if it does.

Personally, I'd pull the fuel pump fuse until after being sure the ignition is working, then try a puff of easy start to see if you get some action. Once I knew the ignition was working, then I'd put the fuse back and try again. It sounds like it's just pumping fuel in, but has no spark to start.
 
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