Timing issue? (Disco won't start)

[syncopix]

Hi,

Hopefully someone has seen this problem before...
1996 Discovery.
Has electrics.
Engine turns over.
Fuel pump primes.
Plugs are sparking.But, it doesn't catch and start.

All electrics are OK. Have cleaned the earth strap and tried a jump lead from the battery negative to one of the lifting eyes on the block, to ensure there's a good earth.

All plugs fire. Have put them on the manifold and checked. Also put them by the ports and can see them igniting the fuel. The plugs also come out wet, so the injectors are squirting fuel in.

Taken the Idle Control Valve off whilst trying to start it, to make sure it is getting enough air.

Tried new HT leads just in case and a new coil. It doesn't cough, so the timing appears to be correct but this is where it gets interesting...

Marked where the distributor was and then advanced the dizzy by about 30-40 degrees and oddly enough, it started! Needed a bit of throttle but after that it did idle near enough. Was hunting quite a bit but then we had purposely changed the timing so that it was way out.

So by advancing the timing it does start. I wouldn't have expected it to do that.

Any ideas? The dizzy is in good condition. No damage, very clean. Maybe its just knackered and given up?

Thanks.

[syncopix]

This is a 3.9 V8 engine. Does it have a crank sensor? Did look for one but couldn't find anything so I guess the timing could be mechanically controlled on this model.

[daveburr]

Did you check the HT leads are all correctly connected up to the right cylinders. Take special care not to swap cyls 5 and 7.

[tcmasterx]

How about a lack of clean air? Is the air filter OK? I had a similar prob on a VW, where there was an pile of gunk that had built up inside the filter and had clogged the air intake valve.

[grieuclarke]

Alarm Spider possibly?? I'm not sure if these spiders stop the engine from turning over completly or allow it to turn of but not fire!!!! somebody will tell us soon.

[syncopix]

Thanks for the replies guys.

@daveburr: Yep, checked all the HT leads+cylinders according to the handbook.

@tcmasterx: Took the ICV off but didn't bypass the air filter. Might be something to try. But advancing the timing solves it, so the air flow is probably OK. Still, it needs to be ruled out.

@grieuclarke: I keep hearing this spider being mentioned. Hopefully it's not that as once again, advancing the time allows the engine to fire and run (albeit hunting all over the place).

I don't think this has a crank sensor but I'm not entirely sure. Never worked on a Land Rover before!

The next logical port of call would be the cambelt. Having to advance the timing suggests maybe the cambelt has slipped a tooth or two.

I've not checked on the status of it. I'll find out what's going on and let everyone know in case it helps someone else out in the future.

[grieuclarke]

Sorry didn't read the bit that said it started if timing is advanced. Doh!!!! just for info there is no timming belt on a V8 it is a timming chain. But if it's an MPI then i'm not sure.

[Satancom]

It really does sound like the leads are not in the right order. Was it running one day and then stopped? Has it never run since you had it?

Simple check would be to pull out #1 spark plug and turn the engine over by hand till #1 piston is at TDC (use a scredriver down the plug hole to feel for this. You will also need to remove the passenger side rocker cover to check that both valves on cylinder #1 are closed, if not spin it round until the piston is at the top and these valves are closed.

Take the dizzy cap off and check the rotor arm is just before #1 lead. If not the leads are in the wrong place, this could be due to a previous owner putting the dizzy back on in the wrong place and just swapping the leads over to match.

To keep the timing you can just move lead one onto the dizzy as its about to fire and then follow the firing order from there on. The books only right when the dizzy has been put in the right way too ;) (I got caught by this:D)

EDIT
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Assuming its a V8