Plug Reads?

[Jetaway]

Diseaszd, esmit208, Gary in NJ and FastWoman: What you are seeing, or not seeing in plug #2 is my lack of photography skills. The center electrode is there and undamaged. What you are seeing as missing or wire-thin is the shadow cast by the top of the electrode. You may be able to see what I'm talking about in the derezed posted pictures, but realistically, it would be a faith-based seeing. I assure you that I went out and triple-checked the plug and the electrode is OK.

Much helpful to respond to, I'll just hit a couple:

First, an appeal for mercy: My plugs aren't usually this bad! I posted up because they were so whacked I couldn't make sense of what was going on with them.

Mr. Beck, I may be a short shifter, but a run to the grocery store a mile away usually puts 15 - 20 miles on the odometer. Slightly more seriously, I don't do the killer short trips in the Z. Any day that I fire up the Z, it gets thoroughly warmed up by running on the freeways or county highway that make an effective loop of the town, even if the destination is a mile from my house. No clouds of condensation follow me around for the first five miles because no moisture is left in the engine and exhaust when I return home and shut it down.

FastWoman: I've used an oil flush twice (when purchased, and then a year or two ago). But, another couldn't hurt and I'll use Sea-Foam as you and so many others have recommended it.

Today's adventures: Drove the Z into work. Twenty miles of back county road warm-up, then a modest twisty workout through a canyon followed by a a decent speed run over the Altamont through Coral Hollow. Couldn't go as fast as I would have liked, but California commuters, even in pickup trucks, even on ancient, narrow, car destruction to the left, death to the right mountain pass roads do set a surprisingly lively pace. Medium speed county highway cruise, one very short 25 mph city patch, then a growling blow out over the Sunol followed by a CHP-respecting 70 mph cruise the last 15 miles on the flats into San Jose.

Many hours later, drove Z back home. A fairly quick trip because traffic was unaccountably light. Would have been quicker except for an abnormal number of absolute idiots out there. I'm gonna, "What the hell? It's like a Saturday out here." Really, it was like Costco had a sale on idiots.

Let's say 170 miles total.

I just wanted to make you jealous with the first part.

Well, that wasn't the only reason.

When I got home, I measured the resistance of the plug wires. Varied from 1800 ohms / foot (plug #5 -- heavy black) to 6950 ohms / foot (plug #4 -- light black) The wires to the whitish plugs (#2 and # 6) measured within 10% of 3000 ohms/ foot.

What I found regarding whether these values were good, bad, or indifferent, indicated, depending on the source, that the wires were good, bad, or indifferent. And there didn't seem to be any correspondence with the plug conditions.

Then I got the bright idea of measuring the coil to distributor wire: 3.4 Million ohms! I didn't bother measuring its length because the highest raw measure I got on the much longer plug cords was 19,000.

That ain't right, right? The coil to distributor wire is made of the same stuff as the plug wires, isn't it? The printed identifier on the wire is exactly the same as on the plug wires, and I can't think of a good reason to use such a high resistance path between the coil and distributor.

Now the reason I brought up the commute was that the Z started to feel a little flat the last 10 - 15 miles where the traffic flow, possibly because we finally got loose of the idiots, hit its customary 75 -- 85 and commenced dicing for position coming into and through the big swing.

So I'm thinking, that while it wasn't hot today by any means, hung around 50 degrees the whole day, but doing 60 miles at a mile a minute, more or less, then a kickup to the 80s would cause some warming under hood. And while a little heat wouldn't have usually been enough to degrade performance, pushing a spark out through three and a half million ohms before even getting to the distributor had to be making the coil work really hard to generate not all that much power to the plugs.

So, I'm thinking that while I may have some other problems, a good first step is to replace the ignition wires tomorrow. Oh, and the thermostat.

Does this make sense? Or am I feeling the effects of something I haven't smoked in a very long time?

Chris

[FastWoman]

Bingo! Yes, your wires need replacement. I'm quite optimistic that will solve your problems. Just as I thought, your ignition was getting weak, and you were starting to get misfires on certain cylinders. I'll bet if you'll find the cleaner plugs gapped just a bit narrower than your dirty plugs. A spark had probably been gapping some distance inside the coil wire.

Do yourself a favor, and use NGK's blue spiral-wound (inductive core) wires. In my experience, they'll last forever and give you a very nice spark. If you need resistance, put it in the plugs. NGK has resistive plugs for that. That said, I never found I needed resistance. The inductive reactance of the core does just fine.

And yes, I'd run the engine at 180.

The SeaFoam treatment I'm recommending isn't an oil flush. I'm suggesting you flush the intake and cylinders. There are procedures described here and there. Basically you dump a LOT of the stuff into your intake until it kills the engine. Then you let it soak. And then you blow it all out and change your oil. This will rid you of your heavy carbon deposits.

Edited February 15, 2011 by FastWoman

[FastWoman]

Here you go:

http://www.autopartswarehouse.com/details/QQNissanQQ280ZQQNGKQQSpark_Plug_WireQQ19751978QQW0133-1625833.html

[Jetaway]

Bingo! Yes, your wires need replacement. I'm quite optimistic that will solve your problems. Just as I thought, your ignition was getting weak, and you were starting to get misfires on certain cylinders. I'll bet if you'll find the cleaner plugs gapped just a bit narrower than your dirty plugs. A spark had probably been gapping some distance inside the coil wire.

Do yourself a favor, and use NGK's blue spiral-wound (inductive core) wires. In my experience, they'll last forever and give you a very nice spark. If you need resistance, put it in the plugs. NGK has resistive plugs for that. That said, I never found I needed resistance. The inductive reactance of the core does just fine.

And yes, I'd run the engine at 180.

The SeaFoam treatment I'm recommending isn't an oil flush. I'm suggesting you flush the intake and cylinders. There are procedures described here and there. Basically you dump a LOT of the stuff into your intake until it kills the engine. Then you let it soak. And then you blow it all out and change your oil. This will rid you of your heavy carbon deposits.

I'll see if I can find the NGK spiral-wounds around town today.

Let me see if I can ask this right: The reason for using inductive wires and resistive plugs is to eliminate, or at the least, greatly cutdown on radio interference. Among the responders to this post, there seems to be a fairly even split between 'R' and non-'R' plugs. I've always used inductive wires and 'R' plugs and don't have a trace of ignition noise through an unfiltered, good sounding, high output audio system. And yes, sound does matter to me very much. So, to finally get to the question(s).

One more background: I do listen to AM. Not extensively, but critically for traffic reports on the "eights."

Do the non-'R' plug users hear radio interference? Or if you did, were you able to eliminate it with simple filtering?

Am I taking a performance hit using the 'R' plugs versus the non-'R' plugs?

Finally, I'll look up the Sea-Foam procedure and put it in the book for the next oil change.

Chris

[Gary in NJ]

I am not using "R" plugs on my 240Z, but I am using the NGK wires. I get ZERO noise in my Alpine AM/FM/CD/MP3 head unit.

[Zs-ondabrain]

I too have BP6ES (Non-R) plugs. 800 watt stereo system, 8 speakers and 2 subs.

My volume runs fron 0 to 40, 20 is loud.

I can only hear buzzing at 1 thru 3, and you can't even hear music at that level.

My exhaust easily covers that up. So if I had to say Yes or no to hearing the buzzing.... Only if you REALLY listen for it. otherwise, NO, nothing audible.

Dave

[FastWoman]

I use B6ES-11 (non-resistive, non-projecting) and the spiral-wound wires. No noise problems here, although I don't listen to AM. I have a fairly nice sound system too.

There's another reason to use the R plugs besides noise. Supposedly the spark duration is lengthened a bit, so that the entirety of the coil's energy isn't dumped immediately in a quick zap. However, the inductance of the wires does that anyway, as far as I'm aware.

I just use what has a long history of working well. I don't get too worked up over tiny tweaks.

Edited February 15, 2011 by FastWoman

[Jetaway]

This amp is special. You see, it goes up to eleven. Normal amps only go up to ten.

(With apologies to Reiner, et al.)

I'm getting the impression that the 'R' status of the plug matters not a bit. I've been happy with NGK BPR6ES's, and with them I will stay. Unless they only have the BP6ES's available in which case, in they go.

Put in a new set of plug wires today. Three words:

Oh, yeah baby!

Cleared up a couple of 'frog in the pan' problems as well.

Thanks for the help. Certainly the immediate problem has been solved and I'll do a Sea-Foam with the next oil change. I'll be keeping a closer eye on the cap and rotor than I have in the past with an eye towards wobbly dizzy syndrome.

Chris

[Travel'n Man]

I replaced the plugs with some cleaned up ones that I had removed early in their life back when I was getting a handle on adjusting the carbs and wanted to get a clean read.

Chris

Chris-

Sorry to catch the tail end of this conversation but if you have not installed new plugs (I have seen the word clean or cleaned a lot) I would trash the the plugs that you have "used" and go only with new ones. Once a plug is fouled I trash mine - a lot of guys will try to salvage them and clean the tips and so forth but it really does not pay off in the long run and the performance of your engine. So, with all the advise above, new NKG plugs, new plug wires - you should be off to the races....best of luck with your project!

[FastWoman]

Yea! Glad it was something simple!