Non resistor spark plugs

[Piotrsko]

Resistance plugs have a longer duration spark (coupling of milliseconds) due to the effect they have on the inductive time constant. Balancing this is the much higher applied voltage to the plug which can double the gap on non resistance. Net results are effectively the same for the ignition event but could be significant in some applications/engine conditions.

Properly functioning non resistance plugs do not emit more RFI than resistance plugs except when they foul

[EcoCivic]

Originally Posted by Piotrsko

Resistance plugs have a longer duration spark (coupling of milliseconds) due to the effect they have on the inductive time constant. Balancing this is the much higher applied voltage to the plug which can double the gap on non resistance. Net results are effectively the same for the ignition event but could be significant in some applications/engine conditions.

Properly functioning non resistance plugs do not emit more RFI than resistance plugs except when they foul

I didn’t realize that the spark will be a shorter duration. But even if it is, I don’t think it would matter much (if at all) because after the air fuel mix is ignited, it becomes the ignition source to propagate combustion, so I think it’s more important to ignite more air and fuel at once.

Great point about the gap! I gapped the plugs to the OEM spec of .0044 inches. Should I have gapped it wider to get the maximum benefit?

[Piotrsko]

Originally Posted by EcoCivic

Great point about the gap! I gapped the plugs to the OEM spec of .0044 inches. Should I have gapped it wider to get the maximum benefit?

They should be gapped bigger,55 thou, but it has been so long since I did spark ignited engines I forgot the rule of thumb. Maximum gap is a mix of various worst case scenerios that prevent effective fire (aka fouling).

Ideally, they should also be indexed, but you need either gaskets or many more plugs.

[serialk11r]

Originally Posted by EcoCivic

I didn’t realize that the spark will be a shorter duration. But even if it is, I don’t think it would matter much (if at all) because after the air fuel mix is ignited, it becomes the ignition source to propagate combustion, so I think it’s more important to ignite more air and fuel at once.

Great point about the gap! I gapped the plugs to the OEM spec of .0044 inches. Should I have gapped it wider to get the maximum benefit?

It does matter, because the air in the combustion chamber is moving. This is why new engines have multiple spark events under some conditions.

I would imagine a bigger gap would be beneficial if the spark can make it across. The resistor doesn't change the potential before the spark forms, so a bigger gap won't produce a spark as easily.

[EcoCivic]

Well I have an update. My engine is still running great, no misfires or coil failures. However, my transmission has intermittently started to shift strangely for no apparent reason. It sometimes upshifts very early while accelerating, then it downshifts and goes back and forth a few times making the car feel like it’s chugging before it straightens out. Engine runs well. It reminded me a lot of when my TPS went bad.

My first step was to put test lights on the shift solenoid wires to see if the ECU is commanding the shifts or if the trans is doing it on it’s own. I found that the ECU is in fact commanding the odd and erratic shifts, so I checked MAP and TPS signals on my Scangauge while it was acting up and they both looked good.

My next step was to swap my ECU with a known good spare. I have a JDM ECU and several spares, so swapping was easy since it doesn’t have an immobilizer. As soon as I swapped the ECU, the trans started to shift correctly again. I initially thought that the ECU went bad since it shifted correctly after I changed it, but then I remembered that the ECU I installed was older and wouldn’t work with my 05’s wideband o2 sensor, so I accidentally changed 2 variables. I put the other ECU back in, unplugged the o2 sensor, and it now shifts perfectly.

So I am wondering if a bad o2 sensor can cause shifting problems, or if the problem is more likely the ECU. I likely have another wideband JDM D17 ECU in my bin, so if I do I will throw that in and see if it still does the same thing with the o2 sensor plugged in.

Maybe the ECU was damaged by interference over a period of several months? Is that possible? Thanks