95 Burb miss

jimh · #1 03-13-2006, 12:47 AM

1995, 350 2 wheel drive with 185,000 miles. It was running fine then it started missing. Watching the plug wires in the dark revealed arcing on a few of the wires. I did a tune up including OEM wires and plugs and put on a heavy ground strap. Still having the miss. The faint spark that I can see is not going from the middle of the wire to manifold, it is around the boot-porceline area. I even tried some of that "boot majic" or whatever it is, just an electrical goo to the plugs. No effect. I know that the engine is getting "tired" but the compression test didn't show anything major. What causes the spark to jump around the plug, even with the new wires? Thanks.

bndfishing · #2 03-13-2006, 07:10 PM

You could have a cracked plug, a carbon trail going down the plug or the plug could be broken inside. The current is going to go somewhere, replace the plug and see if that fixes it.

jimh · #3 03-13-2006, 09:14 PM

Thanks bndfishing, I'll double check the plugs. Like I said, I just put the new plugs in when I put on the new wires, but I know that new plugs does not guarantee good plugs. I actually found a cracked one when I took out the old ones, so I was extra careful when I put these new ones in. Since they are brand new, I doubt if it's carbon trail. What do you mean by "the plug could be broken inside"? Like the porceline isn't cracked but it's still faulty? Anyway, thanks for the reply. I'll post any results.

Not_ Me · #4 03-17-2006, 11:45 AM

Try replacing the cap and rotor.

jimh · #5 03-17-2006, 12:02 PM

Replaced both of those in the fall, but will double check this weekend. Could anything that far away from the plug/wire connection cause the spark to jump from the wire to the block? I would also think that nothing inside the engine could cause this. Even low compression shouldn't cause visible arcing. This one has me stumped.
Thanks for the reply.

Not_ Me · #6 03-17-2006, 07:42 PM

Well resistance does some strange things. Path of least resistance as they say. If you did replace the cap last fall I doubt that this is the problem unless it was a bad cap or it has cracked. Did you check for water inside the cap? This can cause things to act strange.

pnewcomb1 · #7 03-17-2006, 09:47 PM

It could be a faulty boot, or a less than good connection between the wire and plug or even a less than good wire connection to the crimp that connects to the plug.

jimh · #8 03-18-2006, 01:01 AM

Just checked the cap and rotor. Both look good I would have thought so after such a short period of time, but better to check 'em out. No crack in cap and things were clean. I guess I'll go ahead and pull the new plugs and make sure none got cracked when I put them in. Gotta do something besides looking at it and scratching my head.
Thanks for the ideas and keep them coming.

MT-2500 · #9 03-18-2006, 02:52 PM

Pull and check and or switch or try another new plug.
You did use the good AC-delco plugs right?
If the spark will not go threw them it in will jump out.
Have a close look at the plug.
MT

jimh · #10 03-18-2006, 02:57 PM

O.K., just got back from Advance with a brand new batch of AC Delco plugs. Going to try this one more time. Will post results.
Thanks for the replies.

jimh · #11 03-19-2006, 12:04 AM

Well, all new plugs again, and still have miss (spark jump) on cyls 3 & 7. I'm tired of screwing with it tonight. Tomorrow, I think I will switch some wires around, like 3 (bad) and 5 (good), both at the plugs and cap. In the past I have used different plugs and wires, but after reading many posts, I have real live AC Delco everywhere. I sure thought that would cure my problem, BUT NO. I'll post with results, unless I drive it into the river.

Not_ Me · #12 03-19-2006, 10:13 AM

Quote:

Originally Posted by jimh

Well, all new plugs again, and still have miss (spark jump) on cyls 3 & 7. I'm tired of screwing with it tonight. Tomorrow, I think I will switch some wires around, like 3 (bad) and 5 (good), both at the plugs and cap. In the past I have used different plugs and wires, but after reading many posts, I have real live AC Delco everywhere. I sure thought that would cure my problem, BUT NO. I'll post with results, unless I drive it into the river.

Is it just 3 & 7 that are jumping? I Hate to say this but did you make sure you do not have the wires crossed? This can happen to the best now and then. Can't see the froest. Hard to see anything else at this point. ??????????. Try holding the wire plug end close to the plug tip and see if the spark jumps to the plug or the block. This is srarting to sound as if the wires are not in the correct order.

jimh · #13 03-19-2006, 09:11 PM

It's just 3 and 7 now. I was getting spark jump on a couple of other ones also. I did check the wires for correct firing order and it's were good. But you're right, sometimes it's something simple that gets overlooked. It's dark outside now so time for some more testing. I still have the old wires (Autolite Professional Series) and I am going to try some of those on the plugs that are missing.
Thanks

jimh · #14 03-19-2006, 11:35 PM

Stranger yet! I'll concentrate on the odd side. #3 and #7 have a "faint" spark at the boot/plug connection. I have switched plugs and wires with cylinders that do not have the problem. The problem is staying with the cylinder! It makes sense that it's not the plugs or wires, as they are all new AC Delco. #4 and I think #8 also seem to be arcing, with #8 not very often. Any sense to the good one/bad one pattern? I took off the cap again to see if there was any play in the distributer, but it felt good to me. I'll read some more posts about the distributer since this is getting out of my expertice. I guess my questions are, could bad timing or anything in the cylinder cause a good plug/wire to arc?
Thanks again.

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