Fordmods Logo

How to test a coil properly 

 

Page 1 of 1 [ 4 posts ] 

 
 Post subject: How to test a coil properly
Posted: Thu Apr 21, 2016 5:23 pm 
Fordmods Newbie
Offline

Age: 32

Posts: 10

Joined: 8th Apr 2016

Ride: XH Ute

Location: Coolbellup
WA, Australia

Hi guys,

a general question.
I have put a new coil in my car but 2 weeks later it didn't start again.
Now to check the coil, can I just use a spark lead with a spare spark plug and plug this into the end of my coil, fire up the car and check if the spark plug has a spark or is this not a good way of testing the coil?
I read that coils are quite sensitive and I don't want to destroy my new coil, but want to rule out the distributor, as if I have no spark on the actual spark plugs this could then still be the distributor as well.

Thanks
Sebastian
Top
 Profile  
 
 
 Post subject: Re: How to test a coil properly
Posted: Thu Apr 21, 2016 6:12 pm 
Technical Contributor
Offline
User avatar

Age: 27

Posts: 3698

Joined: 27th Sep 2006

Gallery: 20 images

Ride: ED Falcon

Power: 133 rwkw

Location: Leeton
NSW, Australia

You can test with a spark plug...

There is a proper HEI (high energy ignition) test plug but that has a bigger gap, because in the cylinder there is 150 odd psi and it's harder to spark under the pressure... So a HEI plug has a big gap to simulate this difficulty... If you have no spark but then a spark plug with prove it...

Assuming you have an EA-ED or EL

Just unplug the coil wire off the dizzy and stick a plug up it and wedge it against something metal to test...

If you have spark you could have a crock dizzy cap or rotor button...

If you have no spark it could be the dizzy (internal or external module) or the coil...

I made a piece of test gear helps to rule out the good parts and find the problem... But external TFI modules a common problem because they're bolted to the dizzy and gets red hot because it's bolted to the motor and kills the TFI... I remote mounted mine in the end... Ford US actually got sued by the people of America because they proved Ford knew it was a problem and never rectified it... So after that Ford US started remote mounting it on it's own heatsink... I did the same by importing a heatsink and gutting an old TFI to make a loom up...

Do you have a spare dizzy? Just plug it into the loom and leave your test plug in the coil and roll the dizzy round by hand and you should see sparks...

Or it's a multipoint EB/ED they have a coil negative plug at the dizzy, short it ground and that will charge the coil, then release and you should see a spark if the coil is good... EL you'll need to find the coil and get to the wiring on the bum of it...

Cheers,
Tim

 

_________________

93 Red ED 5spd Manual Build Thread

Performance: Complete AUII VCT Wiring & Power Train, Pacey Headers, 2.5" Exhaust, Exedy Clutch, DBA Rotors
Visuals: FG XR Wheel, XR Front, 17's, BA 5 Spd Shifter, BA Ghia Window Switches, NL Cluster
Tunes: 8" Pioneer Sub, JBL Speakers, Clarion Double DIN Headunit

Top
 Profile  
 
 
 Post subject: Re: How to test a coil properly
Posted: Thu Apr 21, 2016 6:22 pm 
Fordmods Newbie
Offline

Age: 32

Posts: 10

Joined: 8th Apr 2016

Ride: XH Ute

Location: Coolbellup
WA, Australia

Hi,

Thanks great explanation.
I have an XH 1999 (no idea what model family that is?)

It all started recently when the car didn't start and I had no spark or pulse.
I replaced the coil and no go.
Then I replaced the cord in between coil and dizzy and off she went.
The cord I got is rather cheap so I wonder if that went again (will replace that tonight)
I just wanted to check if the coil actually gives me a spark (It is new so It probably is OK but better to double check)
I checked 12V at the end of the coil and that was OK.
I have a TFI module ordered now and will replace that regardless.

So If I have spark it can be the dizzy, If I have no spark it can still be the dizzy or coil.
The dizzy is a absolute pain to get to so I hope it is the cord again. Which is probably unlikely but wishful thinking.

I have no other spare parts unfortunately and adjusting the dizzy I think is quite hard so I wasn't brave enough to touch that yet.
By look do you mean the wiring controlling it?
So just to clarify, If I have a spare dizzy, connect the wiring up to that and just leave the ignition on, when rotating the dizzy I should get spark even if the engine is not running or cranking?

I was also told to check the back of the coil for pulse.
When I put a test light into the negative port and the other end on the positive terminal and crank I should get pulse at the back of the coil.
Will I get pulse if lets say the Dizzy is at fault or will this stop the pulse from happening?
Thanks heaps
Top
 Profile  
 
 
 Post subject: Re: How to test a coil properly
Posted: Fri Apr 22, 2016 1:09 am 
Technical Contributor
Offline
User avatar

Age: 27

Posts: 3698

Joined: 27th Sep 2006

Gallery: 20 images

Ride: ED Falcon

Power: 133 rwkw

Location: Leeton
NSW, Australia

XH is EL equivalent...

Do you own a mutlimeter... Just check the lead for resistance from one end to the other... If you get open circuit then the lead is dead...

The TFI is a pain to change, nearly easier to remove the dizzy, then you need a timing light and diagnostic tool to get it back right but...

You're right... If you plug a spare dizzy into the 6 pin TFI plug and turn it by hand you'll get spark... The computer will think the car is running... Don't hook the leads up to it, just use the vanes and TFI on it to get the SPOUT signal...

Yeah... you'll need a incandescent test light, not a mutlimeter or LED test light... One will have a glow when you hook your lead to ground which you have proved is constant power... The other should give a pulsating glow when running as the dizzy grounds the negative wire to charge the coil and then removes the ground to create the spark... To get the glow but you'll need the aligator clamp on the test light hooked to +12V (battery terminal or similar that you can get it onto)...

Cheers,
Tim

 

_________________

93 Red ED 5spd Manual Build Thread

Performance: Complete AUII VCT Wiring & Power Train, Pacey Headers, 2.5" Exhaust, Exedy Clutch, DBA Rotors
Visuals: FG XR Wheel, XR Front, 17's, BA 5 Spd Shifter, BA Ghia Window Switches, NL Cluster
Tunes: 8" Pioneer Sub, JBL Speakers, Clarion Double DIN Headunit

Top
 Profile  
 
Display posts from previous:
Sort by  
 Page 1 of 1  [ 4 posts ] 

Who is online

Users browsing this forum: steve wardle and 16 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

 

 

It is currently Tue Jan 24, 2017 10:12 am All times are UTC + 11 hours

 

 

(c)2014 Total Web Solutions Australia - Australian Web Hosting and Domain Names