Td4 Missfire

Hi everyone. Friend of mine has a 56 plate with a missfire at about 1800rpm. No power loss, no unusual black smoke for a diesel and only occurs when your out of gear and hold the revs pretty much bang on 1800. Don't notice it when your driving and no warning lights. It is a bit nocky at idle, especially when cold but again not really out of the ordinary for a diesel of this milage, approx 80000. Its been serviced as per the intervals with genuine parts and ive told my mate to run a couple of bottles of diesel add throughout but it's still there. I'm guessing an injector goin on experience with mercs (commercial). To be honest, I've told him not to worry about it, atleast for now as I said above you don't notice anything when normal driving. But he is insistent that it needs fixing now. It's his money I guess. Are the injectors a pain to remove? If I remove the plugs to find the bad one, will it put any faults up on the dash that I'll need diag equipment to get rid off? And I've heard from someone that the injectors need coding when theyre changed. Is this true? Thanks for any help.

Injectors can be difficult if seized. The collars and studs around can snap and then it's a real difficult job.

The injectors for the FL are not coded but check for your year the later ones I think were.

You will not be able to see what they are like by removing and looking - I know I did it!

Best get a diagnostic on it as there are so many causes of a misfire - again I know been there and it wasn't injectors.

There is loads on this forum to really mess you up do read and read before doing stuff.

Good luck - oh yeh when was the fuel filter last changed? And has it been correctly serviced?

It had a filter about 3000 ago, this was part of a service. And it's genuine.

Agree with you on getting some diag kit on it. I would imagine this would give an injection comparison to each injector which would be ideal, but I haven't got one and just trying to keep the cost down for my friend.

Thanks for the advise, could still do with some clarification on this injector coding. I know that the later injectors do have coding on them but it's really only the piezo injectors that it's important on. It's oct' 2006 registered if that helps anyone to tell me.

Thanks again.

Just to add, when you say I wont be able to see by removing and looking, do you mean removing the plugs listening to engine note change or removing injectors and looking for a wet/moist nozzle?

When I got mine out they just looked coked up and black - it is no indication of spray pattern or volume.

I am not an expert on this but everyone says you need specialist equipment to test an injector. Leak back can be done cheaply with a rental kit £60 or make one but is a fiddle. Honestly find a local garage with a reasonable test kit and hook it up - probably cost £50 and save more than that.

Just wondering what the outcome was?

I added some Valve Lifter Cleaner from Halfords to the oil and it seemed to improve a low end flying I had - even my wife noticed!

They have hydraulic lifters which can get a bit sticky - a dollop of this stuff seemed to have almost instant results.

Also I have tried different injector cleaners to no real effect BUT took forum advice and used Millers. It dies what they say - well worth it - stick a double measure in to start with and then as per instructions. Halfords sell this as well.

Um..... you have a slight misfire, out of gear, with no loss of power, no warning lights and no other symptoms?

I'd suggest just as gut feeling, you ask another Td4 owner to try it out.

I think you might be describing things that are pretty standard amongst quite a few diesels, as they arent mapped to be held at specific difficult RPM with no engine load for no reason.

Just my own feeling though

i would run it with the fuel cleaner for a while, i had a batch of dirty fuel from a forecourt ,once the tank was empty and new fuel in it was perfect, i could of easy have stripped things down ,glad i never did now

ming said:

i would run it with the fuel cleaner for a while, i had a batch of dirty fuel from a forecourt ,once the tank was empty and new fuel in it was perfect, i could of easy have stripped things down ,glad i never did now

Click to expand...

You talk funny.

storm99 said:

You talk funny.

Click to expand...

that cos i'm a space twot. . . . . . .