As above really,
Had a mate bring his Fiesta round mine Saturday with a misfire on No2.
Replaced the Coil pack with a known good 2nd hand one and it was fine,

He popped back round yesterday and it was only firing on 1 & 4.
Running terrible as you would imagine.

Bought a new Coil pack today and fitted it but still no spark on 2 & 3.
Replaced leads with some old ones we had here and still no spark on the same 2 cylinders.

Checked all fuses, none blown.

Only code stored on ECU is a misfire on No.2

Is there a known fault with these?

I notice there are 3 wires that go into the coil,

As a guess I would say.....

1 earth
2 lives?

Does 2 & 3 get the power from the same wire?

If so how can I check for power at the ECU?
Does it sound like the ECU is damaged?

Please help.

 

Anyone?

 

OK, coil gets feed from ignition on the centre pin, and the ECU grounds the outside pins to fire the coil.

How I check this is with a 'noid' light (basically a low wattage bulb) you could check it with a multi meter or an LED!

One probe in the centre then the other in each of the outer pins in turn (coil disconnected) crank it over you should get a switching voltage on each. Hope I've explained it well enough?

If it doesn't it's either the coil drivers in the ECU are foooked or a wiring fault.

Sometimes a failed coil pack can spike the ECU.

It's not that common, I've probably done 2 or 3 over the years, last one on a Puma about 5 years ago.

 

You can also if you can get yours hands on a loom diagram or auto data and disconnect the ecu and do a resistance test on the 3 wires to eliminate the loom

 

You didn't mention it in your post, but have you changed the plugs? A failed coilpack on my old Fiesta took the plugs with it!

 

That is a good point, also most coils work in pairs so if a plug is breaking down it can shut that cylinder out

 

The switching wires come from the ECU but the power comes from power hold relay usually.

 

Oh ok nearly everything is negatively switched now days then I take it, noid(LED) is the best way as said by"GVK"

 

sorry to hijack the thread, but I have a similar problem, 52 plate fiesta 1.4 petrol, all working fine and now just fails to start and has no spark at all?

Any ideas?

 

If you can get a diagnostic machine on it but it could be the crank sensor? Coil pack, immobiliser?

 

Nothing comes up on machine, no error codes?

 

Fuel? Has it got compression try cleaning the plugs up and refitting them

 

Can the machine you've tried access live data? See if there's an RPM signal on cranking.
(assuming it cranks of course!)

 

Cheers guys, ill try tomorrow,

also, Its not the plugs. if you pull the lead off slightly you can hear and see the spark jumping on the 2 good cylinders, There is nothing from the other 2.

I have a led light tester here in the tool box so Ill try that.

Thanks once again. I suspect the ECU is damaged.

Can it be repaired?

 

Also its worth saying that the middle and far right wires have the same colour trace, but the left wire is totally different to the other 2. would the middle wires still be the live feed even though it has the same colour trace?


Infact I think I have answered that myself as the middle and right wires go back to the ECu and the left wire doesn't so I guess the left wire would be the live feed?

 

On all the ones I've ever seen the centre pin is the live and the outer two are the 'trigger' wires from the ECU.

Worth trying one of the ECU repair people such as BBA reman to see if they can repair these, as I got a price for a Ford exchange ECU for a Focus the other day as it's not switching the fan on, and the price was shocking! Ł990 + vat!!

 

Are these ECU's coded or can I fit one from a scrappy?

 

Need the PATS learning to the car/keys by someone with IDS and an ETIS log in for the access codes, some lock smiths can do these nowadays.

If you got the original repaired if possible, it would be easier.

 

Ok, Thanks for your help,
I will try with a multi meter and my light tester. Will post up tomorrow evening once Im back from Tatton Park

 

i know of a lot of these that loose the coil drivers in the PCM,
Focus do the same also.

only way i check them is with an oscilloscope for pulses

 

Ideally yes, but not everyone has a 'scope... LED test is fine imo.

As I posted earlier, I've seen a couple or 3 over the years, do you see the problem more often?

 

Intresting.Im looking forward to hearing the out come.

 

Won't be any of that, in 2 of those cases it would not run at all, in addition OP said he has tried a coil pack!

Imo, the most likely cause is the PCM (drivers more specifically) as suggested by GVK, hence why it fires on two.

Martin

 

common for the ecus to fail, same as on the duratec ka's etc


some people repair them for Ł175

 

I reckon coil driver in the ecu has failed for 2+3.as these sit on front of the battery they sometimes collect water.drill off the shear bolt carefully and check for any water damage.

if it is the ecu then you will need to replace the coil again even though its new as it will be chicken and egg scenario constantly

 

To save any confusion, there are 2 different people with 2 different problems, Mark has the misfire on 2+3 and matts1 has a non-start.

 

PS, those shear bolts are shit on these Fiestas, Ford dealers have a tubular guide to help drill them straight..ish...

 

I have continuity on the 2 switched earth wires so they are good.
I also seem to get about 4.5volts from each one when the car is turned over.

I checked
middle-left
middle-right

and the numbers jump to about 4.5 and drop when the key is released.
Changed the coil, leads and plugs today but still the same.


Its looking like the ECU is fooked.
Can the drivers be repaired?

Anyone on here able to test it properly?

 

Try an ecu and key from the scrappers

 

yeah I used that guide many a times when worked at ford.one guy drilled straight through pcb and gaffer taped plug back on.we were curious why it came back a day later then we see the hole lol

 

Isn't the immo part of the dash cluster?
don't the ECU and key need matching to the clocks?

 

Yes, the dash on these is the 'gateway' for the immobiliser. Unplug the cluster and it won't run/crank over,anything.

Strange thing about your test, you'd expect to get nothing on the trigger side for 2+3...

Did you try it with an LED?

 

EPIC fail!!

 

No, I used a multi meter.

My led light probe is busted. will try again with a LED from maplins tomorrow