Dwell measurement?

[997at]

Hi Guys,

Is it possible to measure dwell/duty with a digital multimeter that has a dwell function?
If so, are there any instructions on the procedure? Thanks.

[rattlsnak]

I've never seen it done with good results with a digital unit, seems to bounce all over the place but MUCH easier with an analog meter which you can get on Amazon for @$10.00.. Black wire goes to ground, green wire goes to negative side of the coil.

[997at]

Sorry, I should have been more specific. I'm looking to use it to measure dwell for the FV on an '82 SC. Thanks

[fizeus]

hi 997at,
I do not know very well your car but I can only say I often check/fix my dwell with a digital dwell meter.
I have a standard Bosch unit (PN 0231169008).
I'm running a UNI-T digital dwell meter: model UT107
(Multimeter UNI-T UT107 :: UNI-T)
you can find it on the web quite everywhere (eBay, amazon and so on)

How I connect it:
The red dwell meter wire connected directly to to the low voltage pin/spade at the base of the distributor body.
The back wire on the chassis body ground.
Never had a problem, never fired any CDI box.

Also reading is very stable and without any bounce.


Simply do not use the high tension wires of the coil and you will not encounter any problem

Just my cent

[Trackrash]

I have to ask. Why measure dwell on an SC? Can there be an adjustment? What is the spec?

[997at]

I'm trying to measure the duty cycle of the frequency valve on my CIS system. Dwell can be used and converted to duty cycle when measured at the FV test port.
I'm just not sure if a digital meter is effective when hooked up to the test port.
Measuring the duty cycle can indicate if the lambda system is working in part and if the exhaust is rich or lean.

Originally Posted by Trackrash

I have to ask. Why measure dwell on an SC? Can there be an adjustment? What is the spec?

[gazzerr]

An oscilloscope works best because you can see exactly how it's triggering on the up or the down slope of the square wave. I have a Sears multimeter with the duty cycle function and it works but I need to do 100 minus the reading I'm getting because of the way it's triggering. So watch out for that. You can tell when the car is in the o2 sensor warmup cycle in open loop and you get a reading of 35% duty cycle then you have to do 100 minus what the instrument says.