hi all, i have a fiesta zetec 1.6 2003, not firing on cylinders 1 and 4, i replaced ht leads, spark plugs, coil pack, cam sensor, crankshaft sensor, and fuel filter............. car obviously idles rough, on some occassions when the revs are taken over 3k it drives fine and definetly appears to fire on all cylinders until revs drop below 3k then it goes back to only 2 and 3 and has very little power..... any suggestions?

_{Have you put a cleaner through the fuel system lately. If you have it may have dislodged some gunk and is blocking your injectors and if not it may be needs some.}

_{You may also have an air leak into the intake system.}

_{The replacement coil pack may be crap. It took 4 packs to sort our SportKA out and it was only an original Ford one that worked properly.}

_{Last but not least have you tried running it with the MAF sensor disconnected. If it doesn't make any difference, then you know that needs replacing.}

I have just part ex'd the same car. how long have you had it?

hi, right i checked the injectors and they are fine, i dont think an air leak is the problem as this seems electrical as theres no spark on cylinders 1 and 4, my car apparently doesnt have a maf sensor, what it does have is a cold air intake sensor, could this cause a no spark scenario if it is malfunctioning ?

scott, ive had the car 3 months so i dont think its yours.

ALSO just to add its a 1.4 not the 1.6 that i put in my first post.

Try this.

With the engine ticking over can you wobble the plug from the ECU that goes into the coil pack.

If cylinders 1 & 4 chime in the problem is a loose connection.

If that don't work flex the same cable back to the ECU and see if there is a break in the cable.

Try this.

With the engine ticking over can you wobble the plug from the ECU that goes into the coil pack.

If cylinders 1 & 4 chime in the problem is a loose connection.

If that don't work flex the same cable back to the ECU and see if there is a break in the cable.

hi, i changed the connector that goes into the coil so i know there connecting good, a broken wire is definetly a possibility, ive unraveled the wires as far back as possible from the coil checking for damage and as you say i need to check there are no breaks anywhere from the coil to the ecu, is there anyone who would know what pin corresponds with the coil wires at the ecu end so i can put a current through to eliminate that as the problem

or am i missing something else that could be causing it??????????

can anybody shed some light on this?

Looks like most options have been tried. Are you sure you are getting fuel into those cylinders. If so I would try another coil pack. Some coil packs are very specific to the year and model and after market ones will not communicate correctly with the ECU which is the problem we had with the SportKA.

Do you know anybody with the same model of car. I would borrow theirs if you do to see if it works on yours.

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This should be correct for your car;

Coil Pack pin1 Black or Black/Orange wire to Pin 58 ECU (Coil signal ground Plugs 2 & 3)

Coil Pack pin 2 12v Violet/Blue wire.

Coil Pack pin 3 Black or Black/Green wire to Pin 59 ECU (coil signal ground Plugs 1 & 4)

thanks mate, will give it a go later

just to add its definetly not the coil pack, i was worried that is was due to it being a euro car parts copy that i purchased, i swapped the 2 outta wires on the coil plug and it swapped from firing on cylinders 2 and 3 to firing on 1 and 4 so it has to be something else.

i also put a multi meter on the 2 outta wires and they are both sending different amounts of current, someone has suggested maybe its the ecu gone up the wall, anyone got any suggestions? what do i need to change if i buy a replacement ecu, is it a straight forward swap with the key/transponder to match the new ecu?

Sounds like the ECU has been fried.

Did the previous coil pack fail? This can take the ECU with it.

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If you can see a small voltage fluctuation on the 1 & 4 wire, I doubt it would be the ECU, it sounds more like a high resistance in the wire between the ECU and the coil pack, or the ECU connector itself.

A transistor output will either fail as a short or open circuit.

Have you removed the ECU connector and metered out the cable ?

You really need an oscilliscope to check the output from the ECU, at idle RPM the ECU output will be sending a ground shot around 12 times a second.

right, i chased the wires all the way from the coil to the ecu, i actually replaced the 2 outta wires incase there was an internal break i couldnt see, the car is exactly the same..... the thing ive just noticed is that when the cars warmed up to temperature if i hold the revs at around 3k for a few seconds the car actually starts to fire on all 4 cylinders, as soon as the revs drop below 2k even for a second it reverts back to firing on just 2 until i start the process of holding the revs at 3k again.... any idea's where to go next with this?

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In that case I'd suspect an inlet manifold or head gasket leak.

To test this out buy some damp start spray or carb cleaner and while the engine is idling spray it around the cylinder head and manifold area.

If you have an air leak the engine should pick up and run properly for a couple of seconds then drop again.

The area that produces the best pick up will be where the leak is centered.

At the best it would mean a gasket job, at worst it could be the symptoms of a warped head which would need skimming or replacing.

it may seem a daft idea but get the output on the alternator checked out. it may not be supplying the pump with the power to run all injectors at below 3000revs and may be the cause of the rough idle. there seems to be a lot of alternator probs in the car industry in general due to the increased electrical components and the foreign manufacture which is not as robust as the good old brit stuff. keep me posted on how you get on.

After checking no air leaks around manifold or injectors seats:

Going back to basics, using two old sparkplugs, lay the ht leads to the two cylinders on top of engine where they can earth, metal to metal, or use two jump leads to fasten to an earth point and hold each sparkplug in the end of the jump leads.

Start engine and see what the sparks are like or if they are even sparking.

If not then is electric fault.

If plugs sparking okay, refit leads and start engine and try squirting wd40 or similar under the air filter in air intake box and see if engine revs up when you do.

If no change then injectors are squirting ok.

If not then is fueling fault.

Injectors may be getting signal but not working?

Last item is not really likely but have you checked compressions in clys 2 and 3?