How to test GT500 coil packs

[SCCA SM]

Just as the title says, how do you go about testing the coil packs in a gt500?

Everyone likes to talk about bad coils, but I've never seen how to find out if a coil is bad other than just replacing the coils and seeing if a problem goes away.

 

[RedVenom48]

Well for ~$240 shipped you can get a set of ford racing coil packs (OEM coils in a ford racing box). Our cars luckily have no igniter built into each coil pack so they are much cheaper to replace. As a comparison, 1 coil pack on a Lexus RX300 is about $300 retail ona good day. For ONE coilpack.

If in doubt, replace em all.

 

[nxhappy]

you check the resistance in OHMS and make sure they are in spec

 

[SCCA SM]

Well for ~$240 shipped you can get a set of ford racing coil packs (OEM coils in a ford racing box). Our cars luckily have no igniter built into each coil pack so they are much cheaper to replace. As a comparison, 1 coil pack on a Lexus RX300 is about $300 retail ona good day. For ONE coilpack.

If in doubt, replace em all.

LOL, I know I can replace them all. my car has somewhere between 7200 and 7500 miles on it, cant remember. The coils shouldnt be trashed by any means, but i want to test them to try to diagnose an issue im having. Since the car has such low mileage, I would hope they are all legit. Coils shouldnt fail under 10k miles at all, but i want to test them before i drop 300 on new coils and plugs.

you check the resistance in OHMS and make sure they are in spec

I understand that they can be tested in ohms. However, i have read you can run multiple ohms tests on them and have never found a spec that they should be in or a spec that is normal tolerance. i have seen to measure the ohms between the 2 pins on the connectors, and also to measure the ohms between one of the pins and the bit that hits the top of the plug. I have also seen that you need some kind of special test tool and or an oscilloscope.


Can anyone point me in a more home located test before i give up and pay my ford dealer to test them?

 

[Snoopy49]

COIL-ON-PLUG SPARK TESTER THX458

View attachment 2014 PCED JB Secondary Ignition.pdf

JB9 CHECK FOR SPARK AT ALL CYLINDERS

• Ignition OFF.
• Remove the fuel pump fuse to disable the fuel pump.
• Disconnect the ignition coils from the spark plugs.
• Connect the Adjustable Ignition Spark Tester THX458 or equivalent to the ignition coil boot.
• Observe the spark tester at each cylinder while cranking the engine.
• For the 6.2L engine,
• Connect the ignition coils to the spark plugs.
• Disconnect the exhaust spark plug wires from the spark plugs.
• Connect the Adjustable Ignition Spark Tester THX458 or equivalent to the exhaust spark plug wire.
• Observe the spark tester at each cylinder while cranking the engine.
• Is a bluish-white spark consistent between all cylinders?

 

[ShelbyGT5HUN]

Some coils will fail only went hot, and pass the test when cold. Perhaps, throw them in a preheated 250F oven, carefully without melting them, and check em hot!

 

[Nsssane1]

Quick way is if you are getting a misfire code from a certain cyl, switch that coil with another cyl. if the code follows is that coil pack, if not something else.