Not the coils...replaced them with the '89'*. Same thing....ugh...

I'd check the condition of all 6 plugs. Nobody around here seems to like that suggestion.

A bad wire could take out two cylinders.
Check for vacuum leaks.
Is the Cat. OK?

That is a good suggestion & a logical one. I would do close inspection all 6 spark plugs & wires.

i had the same problem on my buddies 96 it was the coils!

Oh yeah, hey good advice on the CAT. We had the CAT plugged up on my wife'* Grand Prix GT and it caused all sorts of power loss at WOT. Get that checked. It could be lots of other things, but that definitely caused a WOT stuttering and threw a code. Make sure to have it checked.

Checking plugs as a last resort. I replace the wires with belden premiums, no change, coils have been changed with those from the '89.

I was reluctant to check the plugs because I just replaced them 2 months ago with TR55'*, and it ran beautifully until a few days ago.

I will go hit the cat around with a hockey stick too.

Oh, and BTW, can a bad ICM cause this? I can swap that in as well if need be...

Crap...I went to pull the front plugs, and I could only get one of them out. I know I didn't overtighten them during the change, I did them all to spec. I was turning so hard I was going to start cracking the plug so I backed off.

The one I did get off had a whiteish/greyish ash type substance all over the insulator except on the tip.

The best matches to the pictures in my haynes I could match it to were carbon deposits or too hot.

So how should I got about getting the plugs out? And what could have caused them to get to this condition?

(1) Buy new sparkplugs, or have other sparkplugs to put in.
(2) Squirt penetrating oil around the plug. Wait a while.
(3) Use a long handle on that socket wrench, with a good quality 6 point socket. Use a pipe on it if you have one. Don't worry about cracking the plug. Just go ahead and crack it.
(4) When plug starts to turn, take socket off and vacuum the cracked plug pieces out of the way, so they don't fall into the cylinder when you do remove the plug.
(5) Put socket back on and continue removing plug.

I always get more plugs than I need when I'm replacing any, or have a spare set if I'm pulling plugs, because I always seem to crack them.

That said, I've never had to pull plugs in my Bonneville, but my dealer put new ones in with the Intake Manifold job.

Well, it turned out to be the plugs. I replaced them and she is back to normal.

Now my question is what would cause a set of plugs to go bad in less then 2 months? All the plugs looked the same, so I know it wasn't cylinder specific.

They all had a whitish coating on them...



Any ideas?