Are the plugs wet after cranking?
If you crank while holding an HT lead near the block, do you see a fat blue cracker of a spark?

 

Thank Greg, Used a spark tester and I get a good spark. Coil and wires are new.
John

 

Paul,
The TPS was new about a year ago and still looks clean. There is no multi function relay, but rather a multi function unit under the passenger knee bolster.
John

 

That's the relay I was referring to. I seem to recall someone had a no start issue that was resolved by replacing, or repairing this unit....it's a shot in the dark. I'm not terribly familiar with what it does, but thought it might be worth investigating.

I think you may be right....the ECU needs to be checked out.

 

Thanks Vee, I will open it up and check it out. If I can't clean it up, i will just get a replacement
John

 

OK, so it is definitely fuel, it would seem. Are the plugs wet after cranking and no start?

 

Greg, I will do some cranking and then check a plug for wetness.
John

 

Greg,.
The plugs are wet when cranking and I know the plugs are firing, as I tested them while cranking as well
John

 

So if its getting fuel and getting spark, it must be that at least one of those is at the wrong time. I don't know the AJ6/AJ16 engine, but is it possible that the injector harness is hooked up incorrectly? Like the plug that goes to the main harness being upside down or something?

Or, remove all but one lead from the distributor cap and try it in every position until I fires?

Is the spark plug gap correct? I know the V12 wants a really tight gap, not sure about the 6.

 

Thanks G, I will do your suggestions.
John

 

John,

As the car seems to be injecting fuel into the cylinders and firing the spark plugs whilst cranking, the implication is that the ecu and other fuelling / ignition signals SEEM to be functioning ok. So I would start by looking at the following potential faults:

- the sparks are happening at the wrong time - Have you checked again the distributor position and the orientation of the spark plug leads?
- the fuel is stale - have you got fresh fuel in the tank?
- the ratio of air to fuel is drastically wrong - have you got any air leaks on inlet manifold? Is the throttle body assembled and operating ok?
- the valve timing is wrong - I think you've confirmed twice that you've checked this?
- the valves are stuck / not sealing - maybe try a compression check on all cylinders? This might also eliminate stuck piston rings etc
- the plugs are fouled from previous cranking - after every unsuccessful attempt at cranking, remove plugs, examine them, clean & dry them.

Paul

 

I removed the multi function module and opened it up. No signs of damage on the circuit board and the plug and the pins are clean and straight.
John

 

MJ:
Next step, get some fast start (ether in reality) and spray it into the inlet while someone cranks, and see if it tries to run.
Normally, if the spark is at the wrong time; but there is fuel, you will get some backfiring, so nothing at all is unusual.
I did check the posts and everyone says the dizzy leads go in clockwise order, so I respectfully ask is this true, as they are anticlockwise on the V12.
Greg

 

The multi function module is operating, as it also controls the interior door lights. tried the plug wires in different orientations, no change, but I am sure I have the distributor and plugs wires positioned correctly. Intake and throttle body are solid, no air leaks. The distributor has a small adjustment slot for fine tuning the distributor position, clockwise and anti clockwise, still no change.
I think all possibilities have been exhausted, with the only remaining culprit being the ECU
John

 

John,

If you're at all unsure if the plug leads are orientated correctly, just post a photo here and we can verify.

My concern as to whether its the ecu is that if you have fuel.injectors spraying and 6 spark plugs firing whilst you're cranking the engine, I'm struggling to see that it's the ecu at fault? Of course, the amount of fuelling could be suspect and the CTS is an influencing factor, but if the engine isnt even coughing and trying to start, thats very strange.

Paul

 

Hi Paul,
Yes I am sure on the plug wires and firing order. After cranking and then waiting some time, and then cranking again, there is a quick, but slight fuel igniting in a cylinder which is probably just left over residual fuel. As I understand it, the ECU controls when and where the spark, and fuel injection is delivered. That is why I suspect the ECU

John

 

Hi Paul,
Yes I am sure on the plug wires and firing order. After cranking and then waiting some time, and then cranking again, there is a quick, but slight fuel igniting in a cylinder which is probably just left over residual fuel. As I understand it, the ECU controls when and where the spark, and fuel injection is delivered. That is why I suspect the ECU

John

 

Paul,
What is cts you refer to?
John

 

Coolant temperature sensor.

 

John,

The CTS (not to be confused with the adjacent temperature trasmitter) is located on the thermostat housing. It sends a signal to the ecu based on the coolant temp it (thinks) it's registering and that influences the fuelling delivery. It's not in any way a guaranteed test but if you disconnect the plug and just bridge the plug terminals, you at least send a different signal back.

Maybe try cleaning the plugs and giving that a go and see if there's any difference at all as you crank it?

Paul