I just changed the spark plugs and wires on my 1999 GM 3.8. The engine ran briefly then died . I went through a diagnostic procedure and and determined that the ignition control module (ICM) was bad. I did not check the gap on the plugs before I installed them but later found out the gap out of the box was too small. The Autolite replacement wireset seemed to be fairly close to the original in length wires on cyls 3 and 5 were slighty longer than the original . Would either of these (small plug gap or wrong wire length) cause damage to the ICM ?

I don't think a small gap would cause much issue besides drive-ability, but a shorted plug gap may cause issues.

I've noticed with new wiresets that sometimes some wires are a tad longer. No big deal.

FWIW - The gap on the plus out of the box was 0.035 . Should be like 0.060 ?

as long as its not shorted i dont see a reason why it would damage the icm. did you pull them and reset the gap? it was likely just bad, they go sometimes

Yes the gap should be 0.060 of an inch. (.152 cm)
What type of spark plugs did u buy?
Stock spec is AC 41-921
I used Iridium on my Buick they run great.
Ar you sure you have the new wires set to firing order correct.
One wrong placed wire will cause problems!

It just seems like to much of a coincidence that the ICM failed at this time. I think that either the plugs or wires made it go .

The plugs are Denso PT16TT 4511 and the wireset is Autolite 96650 purchased at Advance Auto Parts.


I will check the plugs for shorts and regarp them . However , I am thinking that I might install my old plugs (Bosch Platinum not that bad) and original wires (old but no missing and resitence ok) after I replace the ICM .

Any more comments and recommendations are appreciated .

why would you put the old stuff back? wires most times go bad by leaking high voltage to the engine. you cant test that. most you can do is shoot them with water and watch for arcs. plugs wear out too and loose electrical resistance