Spark plug gap and misfiring

[Chris98vobra]

If a car runs well at .028" gap and then you add a DIS4, can it cause misfire unless you widen the gap? If so, by how much. This is an engine with 20lbs of boost.

[msdtech22]

Is the car actually mis-firing or acting as if it is o the rev limiter.

Usually, we have these problems because the MSD adds a high amount of spark energy to the system at the coils.

We recommend using a normal copper plug, resistive or non-resistive, 1 - 2 steps colder than factory recommendation. Stay away from the speciality or 'hype'. We have found they do not work as effectively as the copper plugs.

The gap on the plugs with the MSD is not a standard thing that we can definitely say, "You need this gap." We recommend opening the gap at .005 increments until the vehicle runs smooth at idle and shows signs of burning 'clean' when you read the plug.

http://www.autolite.com/pdf/PlugTips.pdf

You also might look at your wire routing. Make sure that the MSD trigger wires, either a solid white, green, yellow, violet are seperated from the wires going from the MSD back to the coil(s) ( brown/ white, brown/green, brown/yellow, brown/violet)by at least 6 - 8 inches. Running the wires close together will allow the 'rf' energy (an unavoidable by- product of the added MSD CD energy) to induce a 'false trigger' signal back into the ignition causing the engine to act as if it is riding the rev. limiter.

[Chris98vobra]

Sorry, I should have clarified. I feel a slight stumble at low loads and low to medium RPMs. My gap is at .028, where it was before the ignition was installed. I am wondering if the added spark strength could cause stumbling with such a small gap. Have you seen this happen before?

[msdtech22]

Usually, we have these problems because the MSD adds a high amount of spark energy to the system at the coils.

We recommend using a normal copper plug, resistive or non-resistive, 1 - 2 steps colder than factory recommendation. Stay away from the speciality or 'hype'. We have found they do not work as effectively as the copper plugs.

The gap on the plugs with the MSD is not a standard thing that we can definitely say, "You need this gap." We recommend opening the gap at .005 increments until the vehicle runs smooth at idle and shows signs of burning 'clean' when you read the plug.

http://www.autolite.com/pdf/PlugTips.pdf

[Chris98vobra]

Hummmmm......looks like you just cut and pasted what you said before. Anyone else have an answer?

[msdtech22]

I did cut and paste that same area of the previous answer because, yes, the added energy will affect the vehicle by stumbling and acting as if it is mis-firing.

Try using a copper plug and try increasing the gap at .005 increments until the plug looks as if it is firing clean.

[Chris98vobra]

Thanks for the clarification. I am running copper plugs 1 step cooler so will try increasing the gap.

[msdtech22]

Not a problem, anytime we can help.