Car running great and all of a sudden . Hook up to my Acton 9145 and see misfire in cyl 6. I just changed wires and plugs about 1k ago. I check the wire and everything seems ok (Not broken, burnt or close to any other wires including O2 sensor wire). Tomorrow when cooled I will swap wires to see if that is the problem and if that is not I'll pull the plug. My question is;

If one coil goes bad does it affect each plug or can it just affect one?

Each coil fires 2 plugs so I'd check other things first.
Try a new plug.
Swap the wires.
Swap fuel injectors.
Check coolant level - have you changed the intake gaskets already?

For me That plug is the hardest to reach, It may be that you didn't get the boot fully seated and the connector inside the boot is now oxidized adding resistance to the circuit for that plug. I had a similar thing happen with an 86 6000STE, after a few hundred miles it was running rough, one wire boot wasn't seated.

-sp4149

x2 on checking coolant level...have you been slowly losing any?

Thanks for the response. I'm the third owner of the car and the last owner had the car for about 9 years (145K). The upper intake has a date of manufacture of 10-03 which I guess when the reman Jasper engine was installed. I did check the coolant and oil first thing and both were at proper level and color. I couldn't check the boot at the plug as the engine was hot and I'm not going in there until she cools. I'll check that boot first thing then swap wires and see what I get.

I got a bad feeling it may be those darn BOSCH plugs. Why would they sell me those darn plugs in the first place if they are bad? First choice was Autolite which, of course, they were out of. I wish I was more studious on this site before I put them in. I started to read articles here about how bad they are a few days after I put them in. :o I figured since I am NA it would not make a difference but that is what I'm faced with.

BTW, what should the resistance of the wire be? I can just test that with my meter rather than swapping wires.

I dont know if I would blame Bosch plugs I have been using them since the 70s (I used to fix German cars) and never had 1 problem.

I would pull the bad plug before I did anything else so you will know for sure if you may have cracked the insulator when you installed it.

Mark... unfortunately in a waste spark system (our cars) even Bosch themselves admitted their plugs do not hold up well. While I will be the last to merely beat down one brand or anything like that (especially when you see the name on the fuel rail and many other placed under the hood), bosch plugs are simply asking for issues a few months down the road.

Another item to check is ensure the plug wire isn't touching the exhaust or the O2 wiring.

http://www.bonnevilleclub.com/forum/...ode=cat&cat=19

Checked the boot on 6 today and it was on there very snug, if anything it was on real snug as I had a little struggle to remove it. Inside boot the dielectric grease had dried up into a small little puck which I removed.

Plug looked good except for a little carbon and fuel smell.

Checked coils and found my problem. Two coils tested in the 5.8 range but the 3 and 6 still remained at 1, meaning open circuit.

So I'll be off to salvage yard tomorrow and I'll update you after I get it in.

I read the BVille post about the Bosch plugs and it made me chuckle. It reminds me of posts from other forums others have made where they claim to be experts saying silly things.

I use them with great luck since I bought my BVille. Everyone is entitled to their opinions so rather than issue a blanket statement thats silly I try to keep an open mind.