Diagnostic Tool for Testing Coils

[skizot722]

The title pretty much says it all. What's the name of the tool used to test the coils on an LS? I don't have a CEL yet, and I've not seen the CEL flash when accelerating, but I have an itching suspension that one is going bad. My MPG has dropped, and the car feels like the transmission is acting up (what others with bad coils have described the car doing).

 

[gcwimmer]

It would be helpfully if you post year and number of cylinders, may be covered under extended warranty.

They have to be tested under stress usually by a dealer with equipment if you don't have a CEL.

The CEL should give a code with the cylinder but would still need to be tested under stress.

 

[skizot722]

I don't believe it's covered under extended warranty. For whatever reason, that's only for the 2003+. Mine is a 2002 V8.

I understand that the dealer uses an oscilloscope to test the coils, but I thought there was a hand-held diagnostic tool as well, that could be hooked up to one of the ports.

 

[gcwimmer]

That would be a code reader for OBD2 port to retrieve CEL codes. Harbor freight or get it done a auto parts suppler like Auto Zone for free.

 

[Outkast]

I've read alot of coil stories, but this is the first time I've heard of the "flashing while accelerating"....I have that problem...is that a coil?

sorry for the hijack..

 

[joegr]

I've read alot of coil stories, but this is the first time I've heard of the "flashing while accelerating"....I have that problem...is that a coil?

sorry for the hijack..

Almost certainly. A flashing check engine light indicates misfire. It flashes on misfire because that is something that you are not supposed to ignore. You should get it fixed ASAP. You are destroying your cats.

 

[Outkast]

Thanks joegr, I replaced 2 coils recently due to a misfire, and now if I accelerate on the big end...like 70mph + WOT it will flash. It never happens when I'm in town, only on the top end, and no mis or hesitation is noted.

I had planned to replace all the rest of the coils along with plugs this spring, so I guess I'll put a rush on it.

 

[skizot722]

That would be a code reader for OBD2 port to retrieve CEL codes. Harbor freight or get it done a auto parts suppler like Auto Zone for free.

The OBD-II code reader is only useful when the car is throwing trouble codes. I thought there was another tool that showed parameters/etc. of certain systems on the car (one being the ignition system, and includes the coil ouput).

 

[joegr]

The OBD-II code reader is only useful when the car is throwing trouble codes. I thought there was another tool that showed parameters/etc. of certain systems on the car (one being the ignition system, and includes the coil ouput).

Well, you can use a multi-meter to read the coil resistance, but that really doesn't help with the failures that are seen on the LS. They are high-voltage-breakdown faults, and will only show up while being stress tested.
You can get a Ford specific scan tool that will get you all of the extra computer information that is available. I have one from Auto-Tap that is pretty good. You can get a count of misfires for each cylinder, even if there is no check engine code yet. It also gives you neat info such as fuel pressure and a ton of other stuff. I think that about the cheapest I have seen such a tool is around $400. (And even with that, you and the computer are both just guessing about which coil(s) are bad.)

 

[skizot722]

Well, you can use a multi-meter to read the coil resistance, but that really doesn't help with the failures that are seen on the LS. They are high-voltage-breakdown faults, and will only show up while being stress tested.
You can get a Ford specific scan tool that will get you all of the extra computer information that is available. I have one from Auto-Tap that is pretty good. You can get a count of misfires for each cylinder, even if there is no check engine code yet. It also gives you neat info such as fuel pressure and a ton of other stuff. I think that about the cheapest I have seen such a tool is around $400. (And even with that, you and the computer are both just guessing about which coil(s) are bad.)

Sounds pretty interesting. If it tells you how many misfires per cylinder, then you could definitely use that to isolate which coils are going bad as there shouldn't be any cylinder misfires. I know there are other problems that can lead to a misfire, but I'm guessing on this car, the main culprit would be the coils. Do you have a link to the one you purchased from Auto-Tap?

Thanks for the info, guys.

 

[joegr]

Sounds pretty interesting. If it tells you how many misfires per cylinder, then you could definitely use that to isolate which coils are going bad as there shouldn't be any cylinder misfires. I know there are other problems that can lead to a misfire, but I'm guessing on this car, the main culprit would be the coils. Do you have a link to the one you purchased from Auto-Tap?

Thanks for the info, guys.

http://www.autotap.com/

Remember, the misfire counts are the engine computer's best guess. You will, in fact, get some misfire counts on cylinders that aren't misfiring.
The computer detects misfire by looking very closely at crankshaft speed. Sudden drops in speed at particular locations of the crankshaft are considered to be misfires. The cylinder that gets blamed is based on the location of the camshafts. If you hit a bump just right while driving, it could cause a false misfire count on a cylinder. All that said, I have used the counts to find bad coils/plugs.

 

[skizot722]

http://www.autotap.com/

Remember, the misfire counts are the engine computer's best guess. You will, in fact, get some misfire counts on cylinders that aren't misfiring.
The computer detects misfire by looking very closely at crankshaft speed. Sudden drops in speed at particular locations of the crankshaft are considered to be misfires. The cylinder that gets blamed is based on the location of the camshafts. If you hit a bump just right while driving, it could cause a false misfire count on a cylinder. All that said, I have used the counts to find bad coils/plugs.

Thanks, joe. Much appreciated.