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TR plug wires

3217 Views 12 Replies 0 Participants Last post by  Henryk
I removed the distributor caps

I removed the distributor caps, wires, cleaned the contacts and have recorded the Ohm readings on the wires as follows:

Wires 6-1 (from short to long): Right side;

#6 = 900 Ohms
#5 = 10K Ohms
#4 = 12K "
#3 = 10K "
#2 = 12K "
#1 = 12K "

Wires 7-12 (short to long): left side;

#7 = 2200 Ohms
#8 = 1900 Ohms
#9 = 1400 "
#10 = 25K "
#11 = 110K "
#12 = 20K "

These where taken several times with the same above results. The car ran fine......I just thought it was time for new plugs. The plugs where grew to >.045 per plug. However, none where wet......all showed the same amount of black carbon, but not in excess.

Do I need new wires?
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BTW: Both coil wires recorded

BTW: Both coil wires recorded 550 Ohms.

The Ohms are somethi


The Ohms are something like 100 per inch. Measure your coil wires to double check that figure.

Appears you have a couple bad wires, although normaly a bad wire shaws up as an open circuit, but having the wrong resistance isn't good either.

Didn't you have high HC numbers?
JRV: Which 2 wires are you re

JRV: Which 2 wires are you referring to?

Yes, I did have high HC readings. Instead of adjusting the fuel system, I thought it would be a good idea to rule out any ignition problem first......hence the new plugs, cleaning of caps, rotors, and wires.

After looking at how the old plugs where worn, I am assuming that a lot of the high HC reading was due to them.

Well the plugs are in. Idle is now 1250, vs 1000 RPM with the old plugs. I will drive the car today, to let it "settle in" and check the idle and HC readings later today.
Initially the cars idle went &

Initially the cars idle went "hunting" between 1250 and 1000. When I drove it, something was amiss. Turned out to be a missing plug connector, in my haste......put it in and the idle was 1000. The engine runs very smooth.

Will still get new wires.
Great news!!

Sounds like yo

Great news!!

Sounds like you're making good progress getting everything dialed in.

That's excellent!

Regards, JRV
JRV: While the engine ran ver

JRV: While the engine ran very smooth, I went for an 80 mile cruise. When I came back I did some tests.

Tests with the spark plug wire tester revealed that plugs 1-12, with the exception of #3, showed a normal value of between 8K-14K Volts needed to fire the plug......#3 was between 20K-30K Volts.

Prior to replacing plugs, and cleaning distributor contact points, etc., the HC was 380 on the left, and 573 on the right.

Tonight the readings where:

HC Right = 750; Left = 279
CO Right = 0.93; Left = 0.69
CO2 Right = 12.9; Left = 14.3

Obviously something is wrong on the right side.....same side as the #3 plug.

I will order new plug wires, distributor caps, and rotors, from Rutlands.

I will then do the tests again.

What do you think of the above readings? I know that the fuel balance may still be off, but I feel that the ignition should be corrected first.

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Hello Henry,

re. right side

Hello Henry,

re. right side
Looking at the CO/HC/Co2 = sounds like you have an air/fuel imbalance on the right side or misfire. One bad wire (mis fire) may cause this. Your HC's are through the roof. More than likely a cylinder misfire (improper combustion), maybe that no. 3 wire you're talking about.

re. left side
the left side may just be a tad lean (again, a mixture tweak)
or, again, you could have an ignition mis fire, just not as bad as the right side
or, you could have an air leak (false air)

Either way you gotta get the ignition squared away before you tweak CO. But it sounds like once you do get the ignition cleaned up, a mixture tweak would be your next goal (I think anyways)

Are the readings you're posting "post cat" or "pre cat". I'm assuming pre-cat. (I'm hoping pre-cat !

If you're still running that TR on original wires...
shame on you
(sorry, i had to say that) (wires are probably long long overdue)

You may not need Caps, but rotors are cheap and I'd opt for those.

What about extenders ? (do TR's have them ) (I've never owned a TR so I don't know)

Lastly, take all this with a grain of salt until JR gets here to help, he'll get you squared away (I'm just here guessing).
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Joe: The pre-cats are gutted,

Joe: The pre-cats are gutted, and the cats replaced with test pipes......I do have a Tubi exhaust.

In an earlier thread, JRV stated that the HC's should be around 150, so the left side may still be a little rich.

I agree that the right is off the wall......I will replace the wires, car has 70K miles on it. The distributor caps will also be replaced, because I noticed a "groove" in them, where the rotor goes, while cleaning.

Only after the above is done, can I start to play with the fuel settings.

I feel that the ignition system should be correct, before ANY fuel adjustment is made. I don't want to compensate an ignition problem with an improper fuel setting.

BTW: The extenders are OK, per JRV.
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I've seen quite a few bad

I've seen quite a few bad cavis wires in new sets.

Unless you're in a hurry you might want to consider Magnacore Wires.

Check prices on the Cavis Sets if you go that way with Frank @ AW Car Parts & Bill @ GT Car Parts before you leap.
"I've seen quite a few

"I've seen quite a few bad cavis wires in new sets"

ONLY in a Ferrari!!!!!!!!

I'm in no hurry.......the car runs fine, except for #3 plug taking up to 28KV to fire.....where all the other plugs take up to 11KV....average of 6-8. I changed the black connector with another plug, and still #3 is high in KV.......I suspect wire. I will remove the #3 wire from the cap, clean it, test the Ohms, and re-install......hope it works.

I went to the Magnacore site, and they have several styles......which do you recommend?......I don't race the car. How do I get them onto the red rubber boots that go over the plug holes.....or do I need to get new ones?
You send the guy @ Magnacore

You send the guy @ Magnacore your old set, he makes an identical loom with the boots and sends them back.

I just get his standard street size 8mm? 9mm?

The last set I had done was for a Diablo and the price was far lower than a factory set of cavis. Looked great, fit perfect.

If you go with Cavis just make sure you Ohm them all out before install to make sure they're ok.
To send them the wires I will

To send them the wires I will be without the car........will have to wait a few months, till Winter. I took out the #3 spark plug and there was no fouling......all dry.

Now on to adjusting the fuel. While I will get new wires, I don't think it is a major problem in my HC readings.......yet.
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