Question about coils

[trishieldfan]

I have been reading up and reading up on poor idle quality. I am looking into changing coils. i have done all the other things.
Carbon cleaner (seafoam)
ac delco plugs
cleaned tbody
cleaned ground and new battery
idle relearn
My main question is what makes the newer coils different then the older coils. I noticed the gap gets tighter as the years get newer. i was wondering if the newer coils were hotter or just a redesign.

 

[Sparky]

Well, they aren't interchangeable due to the head design change in 2006.

What is bad about your idle, exactly? Can you elaborate a bit?

 

[Mooseman]

Are you getting a misfire code? If not, changing coils will do nothing. Are you sure it's actually a bad idle and not a bad engine mount?

 

[trishieldfan]

I have been getting a random drop in rpm like it wants to stall. Also will stall at throttle opening if I don't give it enough gas. I have read and read but I see either CPS or cpas. Or a few guys have done coils and it helped. I run an auto parts store so getting coils and parts are relatively easy.

 

[Mooseman]

CPAS would be a good idea especially if it's original. Could try cleaning it or replace with GM, Delphi or ACDelco (Dorman are crap). Clean the cam position sensor.

Did you disconnect the battery for 30 min. when you cleaned the tb? Just doing a code reset is not enough.

 

[Reprise]

i was wondering if the newer coils were hotter or just a redesign.

As Sparky said - no interchange is possible - but when I was doing 'coil research' recently, I found a posting on an LS-specific site referencing that the old coils (with the silver heatsinks) were actually the 'hotter' version. Don't know if that applies to the versions for the 4.2L as well, but since you asked about it...

 

[trishieldfan]

I did the proper battery disconnect relearn. Today I started it and it had a dead miss. It had felt like an ignition issue since it started.. changed #3 coil. Cleared the code and fired up and perfect. I'll change the rest on Monday. The idle is perfect and now the idle drop is almost totally gone. I am still going to clean the other two just to be safe anyway. Hoping it clears the little inconsistent idle issues. Thanks to everyone for the responses. I will keep everyone posted on the progress.

 

[Reprise]

I had asked about replacing 'all' vs. 'only needed' coils a few weeks ago; I was advised that failures are pretty isolated.

If you want to replace all of them, you can - but having a new spare would probably suffice if another ever fails. And to be extra safe, test it out (or swap with another old good one) prior to storing it away for future need.

 

[trishieldfan]

With all brand new coils it has almost totally gotten rid of the little stumble. I would like it to be a bit better but i am use to my car which is tuned for response. I may just be picky.