ignition coil

primal1 · August 29, 2005

does anyone know what the tolerances of the coil is for a 99 tahoe 5.7 vortec. the haynes manuel says the resistance between the 2 outside terminals should read .1 on a multi meter. mine reads .5. is that still acceptable. my truck is starting to run choppy and i want to isolate the problem instead of start buying parts. it has had a basic tuneup within 10,000 miles so i don't think it would be plugs, wires, rotor, or cap. i tested the throttle position sensor. fuel filter is new. fuel pump is new. any ideas?

primal1 · August 29, 2005

does anyone know what the tolerances of the coil is for a 99 tahoe 5.7 vortec. the haynes manuel says the resistance between the 2 outside terminals should read .1 on a multi meter. mine reads .5. is that still acceptable. my truck is starting to run choppy and i want to isolate the problem instead of start buying parts. it has had a basic tuneup within 10,000 miles so i don't think it would be plugs, wires, rotor, or cap. i tested the throttle position sensor. fuel filter is new. fuel pump is new. any ideas?

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by the way, ihave 93,000 miles on it.

71GMC_3/4T · August 29, 2005

First of all, check the resistance of your ohmmeter leads. Touch them together. Make a note of that number. Then subtract that off what you read across the coil. Chances are, you had 0.4 ohms in your wires themselves. Don't feel bad, I've made the same mistake at least once!

Choppy? Check the routing of the plug wires. Do not route 5 and 7 anywhere close to each other. They will crossfire and cause grief.

Hope this helps, and Good Luck!

primal1 · August 30, 2005

First of all, check the resistance of your ohmmeter leads. Touch them together. Make a note of that number. Then subtract that off what you read across the coil. Chances are, you had 0.4 ohms in your wires themselves. Don't feel bad, I've made the same mistake at least once!

Choppy? Check the routing of the plug wires. Do not route 5 and 7 anywhere close to each other. They will crossfire and cause grief.

Hope this helps, and Good Luck!

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the wires have not been moved since the tune up. and this is a new problem. i have a pretty decent meter, there is no resistance (that can be measured) in the leads.