[mylesm]

I have a 82 ZXT.... just rebuilt the motor, still runs werid in the mid range

I've been told it could be weak ignition and that upgrading to a 300ZX coil will solve this

my question is, do coils degrate over time, and how can you tell?

my spark is orange, not blue... does this mean it's weak ignition?

also.. can I use a multimeter and see how much current the coil is pulling or check it's resistance to tell?

I can get a good deal on the 300zx coil, and from the sounds of it, it will at least help my gas milage, even if my 280 coil is still good

what are your thougths guys.....

 

[spork]

I know that the spark test doesn't sound to accurate but it has always worked for me and you're right the spark should be blue...I'd replace it

 

[brian83zxt]

i had the same problem with my 83. I would just replace the coil....but you can check it two ways..1) pull of plug check to see if the Blue spark is very "big" in meaning looks like a hot spark. if not that could be the problem.
2) i think there is some way to test it kinda like a starter or alt. but i dont know the name of the tool.
later
brian

 

[johnh240]

A resistance test with a multimeter in accordance with the FSM specs should give you a very good idea if it is good or bad. Typically a coil will break down with heat if it is going to fail, otherwise if it resistance tests ok, it is likely low voltage to the coil or dirty connections, bad plug wires, corroded rotor/cap. Also make sure that the rotor and cap are from the same manufacturer. Sometimes you can get a mismatch of dimensions with different manufacturers and have too wide of a gap for the spark to jump from rotor to cap which will cause a weak spark at the plugs. Can't make it jump too many gaps!! It gets tired!

 

[dave72-240]

An orange arc (say e.g. 800°C colour arc) is naturally not as HOT as a blue one (say for example 4000°C).
Obviously hotter can't mean worse, but that doesn't NECESSARILY mean you don't get as good combustion of a fuel mixture with orange as with blue.

But I'd certainly lean towards that way of thinking.
Mind you, ambient light can affect the perceived colour of an arc.

Are you getting the power you expect? How's the economy?
These are your best measuring devices.

ave
(previously a transformer designer / manufacturer)

 

[Ron Diederich]

Excellent question, as I was just wondering the same thing after cleaning electrical connections last weekend. I believe it has liquid core center. Some go bad if the car has sat for awhile.
I just called Pep Boys and they sell for $30. For that price I'm gonna change mine just because.

Ron

 

[1982jetblack280z]

What effect will it have on a 280zxt if you put a 300zx or 300zxt coil into it? that was a part of his question, and it's peaked my interest =)