Recent weirdness

[OR VietVet]

The gap is important because that can cause too weak or too strong of a spark and cause running problems that can lead to damaged ignition components and parts like cat converters.

 

[iamdub]

I’m really tempted to re-install my Delco ICM and coil. Has anyone tried the Davis Unified “performance” coil? Longer spark dwell is what they advertise.

I'm kinda iffy about lengthening the spark time on dizzy ignitions. I had a MSD on my 4.3 just cuz it was laying around. I was burning through caps and rotors much faster than I should have. Then I learned that the extra spark time/multiple sparks was like multiplying the usage of the conductors in the cap and rotor. To put arbitrary numbers on it as an example: If the parts are rated for 1,000,000 sparks before they're worn, having sparks twice as long or twice the number of sparks would make it reach that 1,000,000 spark life limit twice as soon. If the MSD did make any power, it wasn't enough for me to tell. IMO, stock motor is fine with stock parts unless there's a known design flaw. You're already shorting yourself spark size with the 33% smaller gap.

 

[liquify33]

That has added to my confusion as supposedly GM changed the spec on the iridium plug for these to .040. They were all gapped the same when I received them, had also read not to change gaps on iridium plugs.

These are the plugs I used:
ACDelco 41-993 Professional Iridium Spark Plug (Pack of 4) https://www.amazon.com/dp/B075XWYMYD/ref=cm_sw_r_cp_apip_RaRrCHHrTAKKC

 

[OR VietVet]

From RA: https://www.rockauto.com/en/moreinfo.php?pk=1021537&cc=1353721&jsn=2256


Where it says gap size it says .059. Basically .060 gap.


I found as I read thru the questions people ask, at the Amazon link, about the plugs that someone said they had "HEARD" that the plugs should be gapped at .040 instead of .060 and was asking what they buyer had to say about that. His answer is this:

"I have a 2002 Chevy S10 pickup with a 4.3 V6 engine. It calls for .60 gap for the spark plugs. I bought the AC Delco 41-993 and gaped them to .60. They have been in my truck for a year now.
I haven't had any problems with my engine."


I have never heard of changing the gap to .040. Out of the box the iridium plug should not be regapped. Not good on the center or ground electrodes to move them and especially change the gap by 33%. Needs .060 gap on a new set of plugs.

 

[liquify33]

From RA: https://www.rockauto.com/en/moreinfo.php?pk=1021537&cc=1353721&jsn=2256


Where it says gap size it says .059. Basically .060 gap.


I found as I read thru the questions people ask, at the Amazon link, about the plugs that someone said they had "HEARD" that the plugs should be gapped at .040 instead of .060 and was asking what they buyer had to say about that. His answer is this:

"I have a 2002 Chevy S10 pickup with a 4.3 V6 engine. It calls for .60 gap for the spark plugs. I bought the AC Delco 41-993 and gaped them to .60. They have been in my truck for a year now.
I haven't had any problems with my engine."


I have never heard of changing the gap to .040. Out of the box the iridium plug should not be regapped. Not good on the center or ground electrodes to move them and especially change the gap by 33%. Needs .060 gap on a new set of plugs.

If it comes back I’ll try some platinums at .060 and re-test.

Googling this a couple months ago when I did the work on the intake it seems like the confusion started around 2010 and much back and forth on 40 or 60.

 

[OR VietVet]

I get it. I tend to stick with what I know absolutely for sure and what I don't know I hunt till I am blue in the face to know for sure.

 

[liquify33]

I get it. I tend to stick with what I know absolutely for sure and what I don't know I hunt till I am blue in the face to know for sure.

Looks like I may have another plug vote. Same codes.

 

[iamdub]

I didn't know you had Iridiums. That may make a difference, I don't know.

 

[east302]

Got a cheap scanner and started monitoring closer. It was misfiring at 60ish then moved up to 70 (60 now good). P0300 and P0305 if I left it in the angry zone long enough. Several hundred times according to scanner, felt like I was driving on square tires. Wires are tight on plugs and cap.

Hopefully it’s fixed. If it comes back, the P0305 code points to cylinder #5. The scanner app should have a PID for misfires by cylinder number, so it would be worth checking that to see if it is fixed on multiple cylinders or just one.

Edit: if it comes back and is on one cylinder, try swapping the plug with another cylinder and see if the misfire follows.

 

[OR VietVet]

At RA whether they are copper, platinum, double platinum or iridium, they all call for .060 gap.