EML and misfire

[thespannerman]

Gents

Out earlier today and after driving fine for a while, the engine (2.5 M54) sounded lumpy, like a misfire and EML light came on. Sounded very much like it wasn’t firing on all 6 pots. After stopping and restarting it was ok again. I have plugged my extremely cheap ODB reader in and it’s not showing any stored codes.

A bit of a stab in the dark, but what to investigate first?

Cheers
Al

 

[enuff_zed]

Start by checking all the intake side for holes in pipes. Especially the favourite convoluted pipe on top of the inlet elbow.
Then, maybe try to find someone nearer you with a better code reader/scanner, that may show historic codes.
If it happebs again, plug gthe code reader in while it is still running and hopefully it will give a code or two.

 

[thespannerman]

Ok cheers. As it seems to have cleared after a turn off and on, is it more likely to be something electrical/electronic.

Al

 

[enuff_zed]

Ok cheers. As it seems to have cleared after a turn off and on, is it more likely to be something electrical/electronic.

Al

Well, it could be yes.
Could be the MAF playing up as well.
If it happens again you could try unplugging that and seeing if it runs better?

However, if you have an air leak after the MAF then the sensors tell the DME to add more fuel. It keeps doing this but of course never manages to compensate for all that extra air. So when the DME runs out of adjustment it throws up the EML.
I thought it needed a reset to get rid of that, but possibly just turning the engine off and on again may do it? [ref]Colb[/ref] is more of an authority on this tbh.
Only takes a few minutes for a visual check of the pipes.

 

[thespannerman]

Ok thanks, will go and start looking for holes

Al

 

[enuff_zed]

Ok thanks, will go and start looking for holes

Al

It's a simple start, avoiding the temptation to dive in too deep.

 

[thespannerman]

Just lifted the bonnet, By convuloted pipe on top of the inlet elbow, do you mean the small rubbery one that goes off the elbow in the much larger intake pipe ( the one coming down from the air filter box)

Thanks
Al

 

[raymond.harper]

I would get a better code reader, Creator 410 is popular with the members.

 

[enuff_zed]

Just lifted the bonnet, By convuloted pipe on top of the inlet elbow, do you mean the small rubbery one that goes off the elbow in the much larger intake pipe ( the one coming down from the air filter box)

Thanks
Al

That's the main culprit yes. Goes towards the engine, above the main throttle inlet, and connects (mostly out of sight) to the Idle Control Valve.

 

[Mike6]

If the eml light came on then there must be a error code and as far as I am aware light will not go out unless it's reset. Are you sure it was the eml light or perhaps ignition light in which case you are looking at something different

 

[enuff_zed]

If the eml light came on then there must be a error code and as far as I am aware light will not go out unless it's reset. Are you sure it was the eml light or perhaps ignition light in which case you are looking at something different

Yes, don't confuse the 'EML' light which refers to emission issues, with the Engine Check Light, which funnily enough is a picture of an engine.

 

[thespannerman]

Ahhhh, so my bad, yes it was the engine check light, sorry.

So how does that change what I might start looking for?

Cheers
Al

 

[enuff_zed]

Ahhhh, so my bad, yes it was the engine check light, sorry.

So how does that change what I might start looking for?

Cheers
Al

Ah ok. I’d definitely try to find a better code reader

 

[thespannerman]

Been out in it this morning and it ran fine for about 20mins, then got the misfire feeling, but this time no “check engine” light on the dash. And the misfire seemed to come and go. I know I said my code reader was a cheap one (autel Maxiscan MS309) and this is still not showing any codes.

Could my fault just be a dodgy coil on one of the plugs.

Al

 

[Stevepj]

Had exactly this on mine a couple of weeks ago which was a failing coil on cylinder 5, the difference being my cheap Torque code reader identified the problem.
The next dilemma is do you change just one or change them all and while you're in that area you might as well do the spark plugs too. I'd already fitted new plugs to see if that was the issue, which it wasn't, so went all in with six new coil packs as I was going to use the Z to go to Le Mans for the 24hr race and got a full set for £108 from Halfords.
They're ERA brand and at that time Autodoc we're listing the exact same part, same part number etc, at £38 each.
Anyway, they've done the job, misfire is gone, got to Le Mans and back without any issues including driving 500 miles from Lisieux to Stockport on Monday and queuing and ticking over for two and a half hours to get through passport control at Calais.
Just checked and still available at Halfords for £16.22 each

 

[thespannerman]

Ok cheers, just been and ordered 6 at that price. It possibly has never had a set in its 20 year life as it’s only done just over 71k miles, and we did less than a 1000 miles last year. So for less than 100 quid it’s a easy first step to a fix


Al

 

[thespannerman]

So fitted 6 new coil packs this morning, engine seems smoother at tickover and no misfire after a run out, so hopefully sorted.

Thanks for heads up about the coil price from Halfords, and the daft thing is they source them from Euro car parts.

But who cares

Al