Sounds like a 3 cylinder

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SleepyDawg

Member
Joined
Apr 19, 2021
Messages
51
So, I have a 1.4 which I have been keeping in a garage for the most time. I start it from time to time and today it didn't fire right: it struggled a bit to start, struggled to maintain idle and just run rough. It seemed to me like one of the cylinders is not cooperating. I pulled one of the HT leads out (the shortest one) and it made no difference so I'm guessing that's the culprit right there. Can anyone tell me the fire order on the 1.4 and a good and easy way to test the coil?
Thanks in advance.
 
According to the Haynes Fiesta manual, the firing order is 1-3-4-2.
I'm no expert, but understand that if the cam cover gasket is leaking, then oil can leak into the spark plug hole and cause misfiring.
I have used an Accuspark HT lead tester, with great success to find a weak spark s-l500.jpg
 
Thanks for the reply, John. I tested the coil (the best I knew how) and I got no spark in 2 of the leads. I was convinced the pack was knackered, bought a new one and it still won't work. It's actually worse now as one of the leads where I got the spark seems to have a weaker spark and the car won't even start. Maybe the HT leads are gone? Also, one of the coil bolts is seized...anyone know a trick to take it out?
 
Not sure if anyone is paying attention to this thread, but the problem got worse. I bought new HT leads, a new coil pack, new spark plugs and now the car won't even start. There's no spark in the plugs and for some reason the old coil pack (I was trying variations with the old coil pack and the new leads) began getting real hot. I have no idea what to look for next. I called a mechanic, but he also has no idea (basically did what I had already tried), and he told me he'll get back to me tomorrow with an electrician. If anyone has an idea, please drop a line...
 
Sorry I've no idea. I did check the Mk4 Fiesta Haynes manual to see if the coil needed to be earthed, as you were having a struggle to get the old coil off, but apparently it doesn't need an earth, but may need to be bolted down to act as a heatsink, but I'm unsure.
Do check that you have not got the plug leads muddled up, I had a friend who'd broken down with a classic Mini and somehow he'd got everything muddled up.
I'm sure somebody on here will be a lot more helpful.
 
John Woodward said:
Sorry I've no idea. I did check the Mk4 Fiesta Haynes manual to see if the coil needed to be earthed, as you were having a struggle to get the old coil off, but apparently it doesn't need an earth, but may need to be bolted down to act as a heatsink, but I'm unsure.
Do check that you have not got the plug leads muddled up, I had a friend who'd broken down with a classic Mini and somehow he'd got everything muddled up.
I'm sure somebody on here will be a lot more helpful.

The mechanic managed to get the oil coil off. He was initially unsure if it needs to be bolted down, but apparently it doesn't.
Thanks for the input, mate.
 
To me, this feels/sounds more like an ECU information problem - the ECU isn't getting sufficient info to fire the coil and produce a spark. That might happen if it wasn't getting any positional information from crank or cam, ie cam position sensor/wiring or crank position sensor/wiring.

There might be a way to test the sensors via resistance of certain pins but I'm unsure how to do this.

Good luck with it, hope it gets resolved soon.
 
grogee said:
To me, this feels/sounds more like an ECU information problem - the ECU isn't getting sufficient info to fire the coil and produce a spark. That might happen if it wasn't getting any positional information from crank or cam, ie cam position sensor/wiring or crank position sensor/wiring.

There might be a way to test the sensors via resistance of certain pins but I'm unsure how to do this.

Good luck with it, hope it gets resolved soon.

The mechanic who worked on the car had the same idea. He tested the cam sensor and said it was working well though. He didn't know what else to try as he didn't want to venture too much in dealing with electrical gremlins. He recommended a local electrician.
Really appreciate the contribution!
 
I'd double check that all the HT leads are properly connected at the coil and plugs....once disturbed they can be troublesome.Also check they are correctly located as mentioned earlier...the coil pack should have the cylinder numbers printed on the top face.Double check the wiring connector to the coil pack is properly connected as this sounds to me like the coil is not getting power.
Failing that,Id be looking at the relay and fuse for the ignition module...the old coil pack may have gone into open circuit and blown the fuse..
 
1) the cam sensor is irrelevant to providing the spark, but the Crank Sensor is , which is situated below the starter motor and pointing towards the flywheel. Access is from under the car. If that is faulty you will have no spark. I hope your mechanic has an OBD scanner to identify if his is the culprit?

2) There are 2 wiring harness connectors . 1 of them runs across the top of the gearbox , next to the speed sensor connector. It is the wider of the 2 plugs. Unplug and clean both halves with contact cleaner. The second connector is on the inner wing behind the power steering bottle (bit fiddly to get to). Do the same for that , but that i think is for the fuel injection rail and cam sensor . So go for the gearbox connector first.
 
I think its is important that the coilpack is bolted to the engine and both mating surfaces are clean and the braided wire from the back of the engine cylinder head to bulkhead is in good condition and present.
 
Thanks for the contribution, everyone. I tried the best I could to do what you suggested. I noticed that the insulation of some wires in the engine bay seems to be cracked. This is especially prevalent in the headlights wiring. The car was towed today to an electrician who has a reputation for being thorough, but apparently he still hasn't found the problem. When/if he does, I'll post his findings here.
 
The only electrical problem I had, which took the mechanic a long time to fix, was an earthing problem, something to ponder.
 
yippeekiay said:
DOH said:
the braided wire from the back of the engine cylinder head to bulkhead is in good condition and present.

After all posted so far, this was the only thing I could think to add. I've known them to cause this problem as they can rot/corrode/tear/break/fcuk up :lol:

Good luck finding the problem.

That wire is for equalising the earting potential for the radio (to stop it from making noise and picking up the revs of the engine)
 
If the braided wire is missing or corroded it affects the quality of the voltage to the plugs and also possibly affects the injectors as well ( but not certain about that) . Suppressors i.e capacitors are used to cut noise on the radio, not that braided wire.
You are welcome to remove the braided wire to verify yourself. I noted when I did this that the car was not quite as quick especially on low down pulling power with W.OT. where the spark plug's needs a good earths to fire properly. :)
 
Hi again. So I said I'd return when the car is fixed to tell you what the problem is and...it has been over a month and no solution has been found. First, the electrician told told me it was a problem with the crank shaft sensor...now he's telling me it's a problem with the ECU. He said the ECU is getting current but it delivers no ground...something along those lines. As you can see I'm utterly useless when it comes to electrical stuff but I do get the distinct impression he's guessing rather than following a proper "line of investigation". When the car was dropped there I told him to have a look at the braided wire, the gear box connector, etc. as it was suggested here but I'm pretty sure he did none of that...so what I really wanted to ask is whether the ECU theory plausible? The car sleeps in a heated garage and is not exposed to mice, humidity or anything like that. Again, thanks for the input.
 
I can't really input much here, but I do have a question....

What is the current situation with the spark? Are only 2 of the plugs sparking out of the 4?
"In a wasted spark system, the spark plugs fire in pairs, with one plug in a cylinder on its compression stroke and the other plug in a cylinder on its exhaust stroke." So I would guess the cylinders/sparks are matched 1+4, 2+3.
Are two of those matching cylinders not sparking?

The coil pack is 3 wire. Two of those wires are for the spark signal (one wire for each matching pair of cylinders).
Maybe there is a problem/fault with the wiring on one side..
 
Hi, Cherry.
CherryVimto said:
Are only 2 of the plugs sparking out of the 4?
That used to be the case. But now there's no spark at all in any of the plugs. The leads are new (Bosch) and so are the plugs (NGK). He did tell me that there was power reaching the coil pack (also new = Valeo), though, contrary to what I thought.
CherryVimto said:
The coil pack is 3 wire. Two of those wires are for the spark signal (one wire for each matching pair of cylinders).
Maybe there is a problem/fault with the wiring on one side..

That is my theory as well as the mechanic who worked on the car. But the electrician seems to be following the hardest route first...doesn't really make sense to me, but then again I'm a zero when it comes to electrical problems. I can't even read an wiring diagram properly. For example, I'd like to know if it's possible that in the case of an ECU with no ground connection, power will reach the coil pack..
 
Theoretically, if the ECU had no ground, it shouldn't work at all!

We should be looking at the 'half' method for electrical fault finding.

If there is a problem at the end of the circuit we check the source.
If there is a fault at the source, we know roughly where the issue is.
If the source is fine, we should check the circuit half way between the source and the end.
If half way is fine, we check half way between the middle and the source OR half way between the middle and the end.

Depending on what you find depends on which 'half' you check/test. This way, we should theoretically be able to narrow down which part of the circuit has the fault.

But.. re-reading your post, if there is power getting to the coil pack, is there enough power?
 

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