distributor-less ignition coil output?

[Corik]

I was wondering what the distributor-less (waste spark) max ignition coil output is on the stock 1st gen explorers?
I had an opportunity to attach a scope to my truck recently and was wondering how much reserve capacity I had left.

I realize I could have hooked a spark tester easily enough, but I would like to know what the max coil output is. highest at idle was about 15KV which sounds too high. Wires could be bad, but those were the negative side of the firing order. 4,5,6 the positive side 1,2,3 had about 9KV
maybe just because its reverse polarity??
next time I will try the spark tester. I snapped the throttle a few times and the highest I got was 22KV most were 20 with one at 12KV. Probably shorting somewhere.

Also I would like to know if/what the procedure is for changing idle speed.

I tried to check my timing, so I disconnected the spout connector and started the engine. I was using the scope to see what the reading was and stated 14.5ish degrees BTDC... I know ALL Data says that +-2 degrees from 10 is acceptable( I want to see 10) but it also says idle should be about 675rpm (probably +-50rpm)
My idle was about 800 rpm, should I have simply disconnected the IAC?
the engine was warm...

 

[2000StreetRod]

firing voltage

Thank you for your post! I am in the process of designing a modification to my ignition system but do not have a scope capable of measuring the high voltage outputs. See Ignition Mods & MPG. I am very interested in your measurements since the 1st Gen EDIS is very similar to my 2nd Gen ignition system. My 2000 open circuit voltage is supposed to be 40KV but I haven't measured it.

The voltage reading when the plug fires should be dependent on the resistance of the circuit. Factors that affect the resistance are plug wires, spark gap, combustion chamber pressure, air/fuel ratio, and direction of current flow. Ford attempts to justify their waste spark system by arguing that minimal voltage is lost firing the waste plug because the compression is low on the exhaust stroke. I doubt that and think the main reason was reduced cost due to the simplicity of the system. I suspect the direction of current flow affects the firing voltage because of the different physical shape and properties of the electrodes. The center core electrode is more pointed (especially for platinum plugs) which increases the voltage density.

The lower voltage (12KV) you read on one plug could be due to a lower compression in that cylinder or a reduced plug gap. With your scope are you able to determine the firing voltage for the exhaust stroke plug vs the compression stroke plug? If so, I would like to know the readings.

The Ford factory used to install different plugs in left bank vs the right bank due to the different direction of current flow. I purchase plugs with the same type of material on both electrodes since the wear (loss of metallic conductor) is dependent on the direction of current flow.

 

[Corik]

As far as the low voltage on cylinder #3 Its probably just the spark getting away. I recently put new plugs in and gaped them to I believe .042..basically what the under hood label stated.
I do not believe the scope has the capability to measure the exhaust/waste spark. There were only 6 patterns, I didn't see 12. The scope unfortunately is a digital one NOT a standard oscilloscope that hooks to a distributor, its only a digital representation.
They had one but its too old and no longer works.

I thought it was interesting that you mentioned there were two different plugs installed, one for the positive side and one for the negative side. I have heard of this but My under hood label only stats one type of plug: AWSF-42C
My fuel ratio was the golden: 14.7
The spark plug wires are from a junk yard explorer but the resistance value are much lower than my old wires (kinda sad)

I don't know if I will be able to hook the scope to my car again but I'll try to at some point next week.

 

[Corik]

The reason I want to know about idle speed adjusting is because my idle is 800. I've read many of the readers have a lower idle, so what should I check to try and make my idle lower?

 

[jd4242]

The reason I want to know about idle speed adjusting is because my idle is 800. I've read many of the readers have a lower idle, so what should I check to try and make my idle lower?

http://www.explorerforum.com/forums/showthread.php?t=262930

 

[Corik]

The lower voltage (12KV) you read on one plug could be due to a lower compression in that cylinder or a reduced plug gap. With your scope are you able to determine the firing voltage for the exhaust stroke plug vs the compression stroke plug? If so, I would like to know the readings.

.

I was able to measure the waste spark today, it was about 1.5KV-2KV. Which is normal I believe. normal being about 3KV or lower if memory serves correct.

 

[2000StreetRod]

Waste spark voltage

I was able to measure the waste spark today, it was about 1.5KV-2KV. Which is normal I believe. normal being about 3KV or lower if memory serves correct.

Well I guess Ford was correct when they said the waste spark energy is low. 2KV is only 5% of the 40KV potential. Thanks for posting the information.

 

[Corik]

http://www.youtube.com/watch?v=mkZ_wxo1Dao

The emission tester isn't working, but when I hooked it to a working machine everything was running pretty clean HC around 25PPM and right at the golden 14.7:1 for fuel to air ratio