ukadamwest · Dec 22, 2016

Hi All,

the Classic (3.9 Vogue 1990.. so petrol, and injected) has been running great till a couple of nights ago.. took it out to fill it with some go juice, on the way there and back it was misfiring, having been running perfectly previously.

todayreplaced the HT leads with new, new plugs, new distributor cap, new rotor arm.

still misfiring. anyone have any ideas ? my rave ISO is not loading for the classic at the moment.

frog hopper · Dec 22, 2016

Coil ??

ukadamwest · Dec 22, 2016

its a fairly new coil. not even 500 miles.

myfirstl322 · Dec 22, 2016

Was it an olde worlde garage you got juice at?
Contaminated fuel or you used the black nozzle.

Scotch that, just read it was also bad on the way to filling her up...

Fuel filter?
Injector?

ukadamwest · Dec 22, 2016

i'm wondering if it may be the fuel filter.... i'd be interested to know wammers take on it, seeing as his experience goes back to before all electronics to when a man with red flag walked up front

myfirstl322 · Dec 22, 2016

Who?

It'll be all round lobes n festered plumbing with him, but enough of my cheek about his physical condition

He is without doubt very adept at this sort of thing, he has had a long run at it, which is nice.

2nd guess.....manifold gasket.

ukadamwest · Dec 22, 2016

manifold gaskets been done, it was running fine on sunday, then next time used, misfiring.

myfirstl322 · Dec 23, 2016

Inclement time of year, War Department 40 required.

classic kev · Dec 23, 2016

ukadamwest said:
Hi All,

the Classic (3.9 Vogue 1990.. so petrol, and injected) has been running great till a couple of nights ago.. took it out to fill it with some go juice, on the way there and back it was misfiring, having been running perfectly previously.

todayreplaced the HT leads with new, new plugs, new distributor cap, new rotor arm.

still misfiring. anyone have any ideas ? my rave ISO is not loading for the classic at the moment.

I had something similar some years back. See if the misfire gets worse if you have main beam, heater fan (on full), heated screen and radio all on. If this causes the engine to misbehave you may have an iffy alternator or battery. The only other possibility is the ignition system is playing up so check the usual suspects - Ignition Amplifier, Rotor Arm, Dizzy Cap. Ignition amp is probably the most likely. HTH.

ukadamwest · Dec 23, 2016

Thank you, its got a new ignition amp and remotely located (away from the side of the dizzy), recent coil, new HT leads, new plugs, rotor arm and dizzy cap.

pete1987RRC · Dec 23, 2016

Sounds ignitind based issue to me, have a good double check and whip the coil off and have a look down the connector, I take the rubber shield off coil king leads now cause I always seamed to get damp there which I guess could be condensation? They corode real quick.
The routing of ht leads is also critical, none crossing?

tarphenry · Dec 23, 2016

Just because you have fitted new parts,it doesnt mean that they are are working correctly.

biketeacherdave · Dec 23, 2016

If you havnt sorted it by next week mate I'll pop down and give you a hand I'm off until 7th Jan and as mine is behaving its self after fitting a new rad my spanners are idle will give me a chance to meet the new addition to the human family too.

wammers · Dec 23, 2016

Run it in the dark with bonnet open and look for tracking.

ukadamwest · Dec 23, 2016

thanks dave. i'll get a new fuel filter in too, might as well replace it anyways. And new baby is a peach ( i know all parents say that!)

i'll do that wammers, for sure.

all the ht leads are clipped into the holders, none crossing however i will recheck. the new ht leads were pushing back up due to new rubber and went through them all repeatedly make sure they were pushed down.

seeing as it starts on the button and idles perfectly, but one day it was fine then then the next not, i'm suspecting it may have picked up a bit of dirt from the tank into the filter as the low fuel light was on and the roads are fairly uneven around here so plenty of slopping around.

Gmacz · Dec 23, 2016

wammers said:
Run it in the dark with bonnet open and look for tracking.

Big bonnet on a classic, you will never see where you are going even with the lights on.

wammers · Dec 23, 2016

If the ignition system is a little weak new high resistance carbon leads and plugs can cause orange sparks.

pete1987RRC · Dec 23, 2016

If ignition system is not at fault you could start to look at fuel issues also, which ecu do you have?
My 87 efi had a similar issue which was solved by an ecu swap

frog hopper · Dec 23, 2016

Might not be relevant here but I remember when I had a V8 110 that you needed to take care when routing the (I think) no 5 lead. Something about crossing it with no 7 perhaps? I know at the time it seemed to be counter-intuitive, but always worked for me. Shifted it on 10 years ago so back in the mists of time for me.

classic kev · Dec 24, 2016

ukadamwest said:
Thank you, its got a new ignition amp and remotely located (away from the side of the dizzy), recent coil, new HT leads, new plugs, rotor arm and dizzy cap.

The rotor arm and distributor cap - are they genuine Lucas or cheap pattern items? If pattern, change for proper Lucas.
The coil - is it a standard coil or a "high performance" coil ? The ignition system doesn't like performance coils.
Did you check your alternator output?

Good luck.

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No longer with us, RIP

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