Coil Pack

[Automan1988]

Can the coil pack cause rough idle? When the truck warms up it will drop down to about 550-600 RPMs and sounds like it is going to die. Just got a new multimeter with an inductive pick up and it says that the passanger side bank is running at about 600 RPMs and the drivers side is running at about 1300 RPMs.

I was going to test the coil pack but can't get a reading doing the way that the book says to do it. Any Suggestions or input.

It is a 92 Ranger with the 4.0.

 

[trhull]

If I'm not mistaken the ignition uses a waste spark (sparks twice for every revolution of the motor) on on the drivers side. Not sure if it does it for all cylinders on the driver's side, but that is most likely what is causing it to read double on the drivers side.

As far as the rough idle, there are a few pretty common causes of that in the 4.0L's. Clean your MAF, Idle Air Control (IAC), and check for vacuum leaks.

 

[Automan1988]

The Meter that I am using has two settings for RPM. One is regular and the other is for the waste spark type. The readings were off of the waste spark setting.

 

[ashleyroachclip]

This is the first I have heard about this , waste spark on the driver side cylinders .
Please explain .
Thank you .

 

[MAKG]

That does sound like an ignition problem; the two sides should be identical.

Especially since the coil pack does NOT divide into driver's side and passenger side. It divides into front and back. And if it did, you could expect a rough idle.

That the two sides are different indicates a problem. I'd suspect arcing, but yes, it could be in the coil pack, or in the primary circuits.