voltage readings

[B1keslddr]

hey guys i was wandering if anyone can give me the voltage readings on the coil packs. i am trying to find out if i have the power to the coils. also what voltages should be present at the cas. trying to isolate a no spark problem. thanks in advance

 

[ADrewzki]

You don't do voltage checks to check the coil. You do a resistance check and only after unplugging everything. The CAS, however, you do leave powered. You take it off the intake cam and rotate it by hand. Everytime it "fires," the voltage should be around 4-5V if I remember correctly.

 

[The Foos]

you can do a voltage check to the coils, but not after (if I remember right, the voltage after the coils is 40 kV +, that will destroy your meter, so don't do that). But to check the coils themselves, resistance is basically the only thing you can do with a basic meter. HiPot will tell you more, but most folks can't do that.

As far as no spark, what isn't working? No spark on all cylinders? No spark on 1 and 4 but spark on 2 and 3? Can you give a little bit more info?

Scott

 

[Talesin]

As an aside, what kind of voltage does a stock 1G usually run? Highest I get from my Apexi TT is 13.7, lowest... well, usually runs at around 12.9, but can drop to 11.8 sometimes over a long period. Thinking either a failing battery or alternator, as that sounds pretty unhappy.

 

[luv2rallye]

You can't do a voltage check on the coils without an oscilloscope because the low going pulse from the power transistor (or ECU) is too short. A multimeter will just read +12V on both sides of it.

 

[The Foos]

That is correct, but just knowing that there is a signal (no matter what it is) is probably good enough...every tinkerer should have an o scope anyhow, but that is a different topic.

Scott

 

[luv2rallye]

...but just knowing that there is a signal (no matter what it is) is probably good enough

As long as you understand that +12V there does not mean the power transistor (or ECU) is necessarily good (it can read +12V even if these are bad). It just proves there is continuity to the power source. And less than 12V indicates a problem since it comes right from the battery (thru a fuse, relay or ignition switch).