Thread: My misfire problems still and agian

Is it blowing steam or smoke?.Have you tried a different ignition module?,is it using coolant?.If one cylinder is burning oil or using coolant that will cause a mis-fire.One thing to try is to pull no.1 plug and see if it is clean or oily if you think that cylinder is the trouble. Pat

Definitely steam

Everything to do with spark is new the plug does spark the lead works button cap are new Lucas injectors have been changed even the engine

I have learned my lesson its been an expensive one its time for it to go

WOW, that's what I call diagnosis by replacement on a Grand scale.

Aside from your assembly stuff up which now needs to be redone it is obvious to me at least that it is something you have NOT replaced.

First I would not assume the injectors are OK. Maybe swap them around and see if the dead cylinder remains 1. If so have a look at the plug and loom. It is not unknown for the wires to break inside the loom near the injector plug as they get hard there.

Have a look at the valves going up and down with the rocker covers off and make sure that they are on 1, although I assume the new motor had a cam in it.
Did you replace the coil and the ignition amp?

Although if the misfire is on one cylinder its almost certainly plug/lead/ injector/ camshaft related. Did you have the head serviced before putting them on the 3.9? if not could be a sticking exhaust valve.
Regard sPhilip A

At this point i can guarantee that it has spark my mate almost turned into a roasted mate when he got stung by it

On cylinder 1
When i remove the lead it sparks up ok and makes no difference to the way the engine runs
when i unplug the injector it makes no difference
But does on all other cylinders
The plug (s) have been changed more times than i can count swapped around and juggled

ignition amp? where do they hide that on a Discovery 1 its not on the dizzy

Is there any way of testing to see if the injector is getting power when it needs it

Well first I would switch 2 injectors to see whether it is the injector, but if the miss occurred on that cylinder before you put in the new injectors then it is probably the loom.

All the injectors on one bank fire at once so the power to one injector can be relayed to another with a jumper lead or two. I would strip off the outer tube and visually inspect the wires first. If you see a break then it is Eureka. You can buy the plugs on ebay and just insert a new bit of wire and crimp it to a good bit of loom..

I would think a multimeter would see if current was at the plug if set even to 12V, as a series of pulses although I haven't done it.

Regards Philip A

Steve is this the engine you boiled?.The steam could be coolant in the exhaust boiling off.Like PhilipA said,check you have power to each injector as you might have not connected it all up right during re-assembly. Pat

No this is a different engine
I'm going out now to double check the wiring but its pretty much idiot proof sorry Steve proof

Originally Posted by steve_35

And just to dig the dagger in it is now blowing huge clouds of steam when i start it probably leaking in through the intake gasket cause it didn't get machined when they fitted the old 3.5 manifold on the 3.9

I doubt a water leak would make it to the intake ports, there's heaps of seperation. Water on the valley cover yes, but thats about it.