Hello Forum,

i am having issues with my Blazer 4.3V6 MY 97 and would like to know if
forum collegues have seen similar failure mode.

My sencondary voltage on the coil dropps from 20kv to 8 kv. sse picture.
I have no failure codes listed and my blazer is undrivable. It

Maybe you have an id what can cause this.


BR
Bob

 

Normal firing voltages at idle may vary from 5 KV to 15 KV, but there should be no more than about 3 KV variation between cylinders.
A higher firing voltage indicates higher than normal resistance in that cylinder’s ignition circuit. This may be due to high resistance in the spark plug wire, a wide rotor gap, high resistance in the spark plug itself (worn electrodes or gap set too wide), or a lean fuel mixture.
A lower than normal firing voltage means decreased resistance. Causes include shorted plug wire or spark plug, grounded or fouled spark plug, an overly rich fuel mixture, or possibly low compression.
You have to do a cranking KV test and/or snap KV test to stress the ignition system

 

^^^ I agree. But with all 6 cylinders at 20kv, (at the beginning of the graph) and then drop to normal, I'd check for something that is common to all 6 cylinders, ie ignition coil, coil wire or distributor rotor. It's fairly common for the coil to short to ground, especially on start up or under a load. Try spraying a mist of water at the coil, (after dark) and snap the throttle. If you see sparks, that's the problem.

 

Thank you Hook & Burned.

I did some addional measurement yesterday. I have recorded the EST and out put on same timebase.

And I put an MSD Digital with MSD coil in. It ran much better but could not test drive it. I was getting dark.



Here my measurements.

I would like to buy a coil. So many products from $19 to $99. For sure I am not buying Made in China.

Which coil can I take???

 

FYI

I temporary build in a MSD 6AL digital with coil in my Blazer.

This is another $ 300 bugs. The car runs fine with an MSD

So I will start replacing the coil & then the distributor cap

BR
Bob