miss fire suggestions please

[meatball]

Hi chaps i could do with some suggestions for the cause of my miss fire. Ive just changed my valley gasket today and the car didnt have a missfire before. The miss fire is only under load but fine on idle and there no hesitation if i blip the throttle whilst parked?.
The distributer and leads were left in situ and not touched whilst changing the valley gasket.
I left the injectors for about 2 weeks wrapped in kitchen roll, could this be the problem?
Also the exhaust is spluttering more than usual (could an injector be stuck open?)
i`ll check the electrical connections again at the weekend.

any ideas

Edited by meatball on Wednesday 7th March 20:24

[antonyj]

I had a occasional misfire last year, it turned out to be a loose spade in number 4 injector plug.
They can come loose and pull back away from the injector connections.

Might not be the solution, but worth a check whilst hunting.

[meatball]

antonyj said:

I had a occasional misfire last year, it turned out to be a loose spade in number 4 injector plug.
They can come loose and pull back away from the injector connections.

Might not be the solution, but worth a check whilst hunting.

Hi antony do you mean the square metal clip on each injector?
cheers ben

[antonyj]

yeh , thats the one, I believe they are called "mini-timer" plugs.

Of course its best to try and find out whether its fuel or sparks that causing it.
When you suspect its doing it, try (using insulated ,or better plastic, pliers) removing each HT lead, either from the plug or from the dizzy in turn.
Hopefully, the revs will change and help you id which one it is causing the miss.

Of course thats if its something affecting just one cylinder.....

[fastandcurious]

Dodgy supermarket fuel perhaps?
There's been a lot of it about just lately.

Edited by fastandcurious on Wednesday 7th March 22:39

[Rum Runner]

Plug shroud ? , is there a any ticking are arcing sound anywhere !.

Edited by Rum Runner on Wednesday 7th March 22:51

[meatball]

Its definately not a petrol issue as its been layed up over two weeks
The shrouds have not been touched, but i will try that.
What do the injector clips do?

[Rum Runner]

Hay you pulled the plugs out and cleaned them just in case and debris e.t.c got onto the plug itself via the inlet port if a valve was open.Go for the simple thing first.

Edited by Rum Runner on Wednesday 7th March 23:11

[Griffter]

meatball said:

What do the injector clips do?

Crossed wires I think (excuse the pun). anthnoyj is talking about the actual female electrical connector, of which there are two inside each plastic injector 'plug'. These are prone to damage and consequent intermittent contact if the plug is put back clumsily.
Having said that if I disconnect (any) one of my injector plugs the difference is just a bit more lumpiness - not a misfire as such. Did you seal the plenum when you put it back? Could be an air leak.

[Podie]

Rotor arm...?

[miketvr]

I had a problem with one of the plug extenders/suppressors failing which caused misfiring. You can remove the majority of them for a trial and then swap the remaining (two rears from memory) with two others for a further test.

Mike

[robinracer]

Hi
mine has just been to the doc's for the same reason.it was running rough and missfiring.
the problem was the distributor cap had split.changed the the cap and rotor arm all fine and dandy.
hope this helps

[meatball]

cheers guys i hope its that simple the only thing is the dist cap, rotor arm, plugs, plug shrouds and leads are all new???
im thinking more along the lines of injector area as this was the area i was in?

[GasMonkey]

meatball said:

cheers guys i hope its that simple the only thing is the dist cap, rotor arm, plugs, plug shrouds and leads are all new???
im thinking more along the lines of injector area as this was the area i was in?

With the engine running, get an old cable tie and touch the end onto the exhaust manifold for each cylinder. It will melt on the cylinders that are firing - you will find the misfire this way.

Pull the lead out and connect an old spark plug, earth it off the head,
if it fires, you need to check the injector is connected
if it doesnt fire - remove the plug from the engine and clean / replace

[meatball]

GasMonkey said:

meatball said:

cheers guys i hope its that simple the only thing is the dist cap, rotor arm, plugs, plug shrouds and leads are all new???
im thinking more along the lines of injector area as this was the area i was in?

With the engine running, get an old cable tie and touch the end onto the exhaust manifold for each cylinder. It will melt on the cylinders that are firing - you will find the misfire this way.

Pull the lead out and connect an old spark plug, earth it off the head,
if it fires, you need to check the injector is connected
if it doesnt fire - remove the plug from the engine and clean / replace

excellent idea
thanks

[meatball]

GasMonkey said:

meatball said:

cheers guys i hope its that simple the only thing is the dist cap, rotor arm, plugs, plug shrouds and leads are all new???
im thinking more along the lines of injector area as this was the area i was in?

With the engine running, get an old cable tie and touch the end onto the exhaust manifold for each cylinder. It will melt on the cylinders that are firing - you will find the misfire this way.

Pull the lead out and connect an old spark plug, earth it off the head,
if it fires, you need to check the injector is connected
if it doesnt fire - remove the plug from the engine and clean / replace

Gasmonkey your tip worked a treat it took me straight to the missfire
Wanna know what was causing the missfire???? my mate who was working that side didnt push the injector multi plug on rightplonker

Any way as the locals say were i live "THAT A LEARN YA"!!!!

[GasMonkey]

meatball said:

your tip worked a treat it took me straight to the missfire
Wanna know what was causing the missfire???? my mate who was working that side didnt push the injector multi plug on rightplonker

Any way as the locals say were i live "THAT A LEARN YA"!!!!

Yeah, I did the same when I changed my valley plate!! mine had misfire on 2 middle cyls on the left bank- did your valley gasket come flat? Took me ages to bend it into a V shape !! - The old cable tie trick is a good one to locate a misfire !

[meatball]

GasMonkey said:

meatball said:

your tip worked a treat it took me straight to the missfire
Wanna know what was causing the missfire???? my mate who was working that side didnt push the injector multi plug on rightplonker

Any way as the locals say were i live "THAT A LEARN YA"!!!!

Yeah, I did the same when I changed my valley plate!! mine had misfire on 2 middle cyls on the left bank- did your valley gasket come flat? Took me ages to bend it into a V shape !! - The old cable tie trick is a good one to locate a misfire !

Spot on gasmonkey it came flat and was a :censord: to line up and bend into the right position. I took it out today and gave it a good hoon and so far its not leaked so fingers crossed.: