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Home > Help Needed / General Tech Chat > Fried Coilpack?

e5tus

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273 Posts
Member #: 10128
Senior Member

Dorset

Morning all,

Following my cable shorting and losing all power last week, I installed the new battery and cables (with cut-off for good measure). Car started up fine, ok at idle and low revs but not happy under load, misses and wont rev up.

My first thought was MJ not being happy with the on/off power before the car died, all fuses ok. Connected to laptop and map is present and it's working as usual.

Next thought is coilpack maybe? Do they play up like the old coils when they are breaking down?

Going to run through all the earths later, as the main battery earth was toasted, could be a small earth to something has melted.

Any other thoughts welcome. Thanks, Stu


Rod S

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5970 Posts
Member #: 2024
Formally Retired

Rural Suffolk

It's possible but my own personal experience when one failed on me was one half failed completely, just went open circuit so I went straight down to 2 cylinders.

Bear in mind if it's one salvaged from a breakers it will be donkeys years old and if it's new you've either paid an absolute fortune for a genuine Ford one or it's a cheap chinese copy (and even if it's a genuine ford it will have been made somewhere cheap).

Put a multimeter on it (disconnected), just to measure the resistances, HT and LT and see if either side is different to the other, esp. the HT. Also check for any low resistance between any of the HT posts and the metal of the frame at the bolt holes.

Schrödinger's cat - so which one am I ???


e5tus

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273 Posts
Member #: 10128
Senior Member

Dorset

Went over everything with a multimeter, nothing appeared out of the ordinary.

I threw a new coil pack on as I had one but still not happy under load.

Measured battery voltage and when running with lights on at idle I was getting 14.2v, increased up to 16+v when revved so I shut down. Think the alternator regulator may have been cooked.

I'm not sure how this has an impact on all the other components (EDIS, ECU, coil etc) but I'll address it now I've found it.


e5tus

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273 Posts
Member #: 10128
Senior Member

Dorset

Alternator changed, voltage output is now as expected. but still running like a bag of shit. I've got another EDIS, so maybe throw that on. Otherwise it's back to pointing the finger at the MJ. Although laptop is showing it receiving the right signals and using the map, guess it may not be outputting it? Not sure. Some thinking to do


Rod S

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Member #: 2024
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Rural Suffolk

What do the spark plugs themselves look like ?
Any obvious fouling on one or two only.
The Ford wasted spark coilpack setup is quite wierd because the way it fires two plugs at once, one gets +ve voltage and the other gets a -ve.
So not all plugs are treated equally.
Modern plugs generally cope with it OK - back in the day Ford used to specify different plugs for different cylinders.... - but it's worth looking at all of them and swapping 1-4 and 2-3 and see if it makes a difference.

Schrödinger's cat - so which one am I ???


e5tus

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273 Posts
Member #: 10128
Senior Member

Dorset

Thanks Rod, all four are fouling. Changed the leads (and swapped order around too, in case new coilpack was ordered differently)

Timing light confirms megajolt output is correct. Crank position wheel is correct position and sensor is normal location.

It runs, but dog rough. Very rich.

Going to check fuel pressure later, confirm it's not a duff regulator giving me too much fuel. Otherwise, I'm going to have to start taking it apart. Few people have suggested a compression test in case when it the power was on/off/on/off before it dies that I didn't miss a couple of strokes then get spark and detonation. Hope not, but rapidly running out of ideas and enthusiasm!


burcy35

173 Posts
Member #: 10990
Advanced Member

Hornsea

I had a very similar problem which belive it or not ended up being a cracked exhaust manifold. It was probably my fault as I wrapped it and must of got too hot. It's mainly used as a track car so it gets plenty of hammer. Worth a look .
Roy B


Rod S

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Member #: 2024
Formally Retired

Rural Suffolk

Sounds like a fuelling issue rather than coilpack (or anything ignition related).
Regulator or leaking float valve would be the obvious ones.
Anything else you did to it with your previous problem that may shed some light ?
I wouldn't worry about detonation even if you think you hear it, rich mixtures burn slow, not fast. What you could be hearing is just mechanical noise from uneven running because of the misfire.

Schrödinger's cat - so which one am I ???


e5tus

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Member #: 10128
Senior Member

Dorset

On 21st Jun, 2021 burcy35 said:
I had a very similar problem which belive it or not ended up being a cracked exhaust manifold. It was probably my fault as I wrapped it and must of got too hot. It's mainly used as a track car so it gets plenty of hammer. Worth a look .
Roy B


Thanks Roy, Taken inlet and carb off last night, mine is wrapped too, looks like a little blow by on the turbo/exhaust join, but will get it out later and inspect.


e5tus

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273 Posts
Member #: 10128
Senior Member

Dorset

On 21st Jun, 2021 Rod S said:
Sounds like a fuelling issue rather than coilpack (or anything ignition related).
Regulator or leaking float valve would be the obvious ones.
Anything else you did to it with your previous problem that may shed some light ?
I wouldn't worry about detonation even if you think you hear it, rich mixtures burn slow, not fast. What you could be hearing is just mechanical noise from uneven running because of the misfire.


I tend to agree with you on fuel, now that everything in the ignition system has been changed, inspected and verified. Carb came out last night, when I undid the first dash pot screw sounded like the piston/plunger fully retracted, could well have been the issue, open somewhat all the time.

Would figure as why it was running rich and not happy until it went past that fuelling point.

On rolling road, after the needle was fettled by Neil, we had a similar problem, thought it was due to dash pot sitting on the seal at one point. But maybe there's something out of tolerance in the piston/plunger assembly.


e5tus

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273 Posts
Member #: 10128
Senior Member

Dorset

Oh, and did measure the fuel pressure, 3.8psi at idle/pump only state.

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