Author Topic: ignition wires (Read 16318 times)

enochbell · « **on:** July 05, 2012, 15:28:19 »

I have had an intermittent problem with rough running after warm-up for quite a while, I bugged this board about it several times and followed all the advice, but the problem persisted. I did a restoration, including complete overhaul of engine, 15 years ago, in my garage. Since then I have never had a problem I couldn't solve, with you guy's and gal's expert advice, for which I am grateful.

So I finally gave up on fixing this rough running problem myself and took the car to an indy here in Atlanta (John Herzler, RS Motorworks, Atlanta, highly recommended) who diagnosed the problem just by listening to the engine. Bad ignition wires, he said. No way, I said. I put those in myself not 10,000 miles ago (1997)

I bet him a cup of coffee that he was wrong. I am on my way to Starbucks to get his grande latte.

Best,
g

114015 · « **Reply #1 on:** July 05, 2012, 18:00:22 »

Superb advice, Enochbell,

... Thanks a lot !!

Achim

Eminent · « **Reply #2 on:** July 05, 2012, 21:52:11 »

Well, it looks like i have the same problem. With a cold engine (and colder weather) the engine runs smooth. After a drive in the better weather the engine runs rough also. Not perceptible when driving, only at idle when i'm waiting for traffic lights or so. A week ago when i opened the hood i heard the sound of arcing. I repeat this when it was dark and sprayed some water on the wires. I saw sparcs on several places. Most at the wire from the coil to the distributor which was close to the bodywork. The wires are not that old and from Beru. I'm gonna chance them but i wonder if it has something to do with the powerfull red Bosch coil.

Harry · « **Reply #3 on:** July 07, 2012, 02:06:13 »

What type of wires did you have and what did you replace them with?

enochbell · « **Reply #4 on:** July 07, 2012, 13:58:29 »

Both the old and new are Bosch. I have to assume it was age, heat cycles and bad luck that was the culprit. All I know is that I spent a lot of time on the WRD, TTS, CSV, injectors, fuel pump...oh well. I have actually never spent an hour with this wonderful machine that I have not enjoyed.

g

Benz Dr. · « **Reply #5 on:** July 10, 2012, 03:16:14 »

Bosch wire sets often have carbon core coil wires. Your engine will never run properly until that's fixed, if that is a problem.

enochbell · « **Reply #6 on:** July 10, 2012, 13:29:27 »

Thanks Dan, I will check them when I get back home, if I get back home. What is your recommendation for wires? I thought Bosch were OEM?

g

Benz Dr. · « **Reply #7 on:** July 10, 2012, 18:59:14 »

I think Beru would have been what your car used back in 1964. Bosch sets are OK but they're often set up for engines using carbs. The number one spark plug wire may be a 90 degree style and it may have a 5 ohm resistor in it. This part, and the carbon core coil wire can be changed without buying a complete new setb provided that the rest of the wires are OK.
I carefully pry open the metal ends on ther coil wire and re use them on a steel core wire.

ja17 · « **Reply #8 on:** July 10, 2012, 22:31:52 »

Checking the ohms resistance of ignition wiring with a multi meter before every tune up will diagnose most wiring and wire end problems. Even a $5.00 multimeter from Harbor Freight will do the job.

Harry · « **Reply #9 on:** July 12, 2012, 20:36:40 »

Wgat specifically should you look for in a spark plug wire for these cars? I ordered a set from Parts Geek that has what I believed to be the old style with the metal cylinder at the plug. The car had a different wire when I bought it. I'd sure like to know what is the BEST wire to use and avoid this variable in any running issues. (BTW - right now my 230SL runs very good.)

Harry

ja17 · « **Reply #10 on:** July 15, 2012, 15:00:53 »

First of all look to make sure the inner wire is metal not carbon wire. The real wire will be stranded copper with a silver colored coating (tin). As with the original wiring, the copper wires will not fail unless the outer insulation goes bad. Today most wire sets use a carbon filament wire which has a built in resistance of around 5,000 ohms. The carbon wires break down and fail more often. In addition the ignition systems of the pagoda were not designed for the extra 5,000 ohm resistance.

The next most important thing to look at is the wire ends. Most likely the wire ends will have a resistance built into them also. The original Pagoda sets used wire ends that unscrewed and could be replaced if they go bad. The spark plug connector is also designed to be used on spark plugs with just the bare threads showing on the top of the spark plug. The little screw on fitting which comes with the spark plug is removed or left off.

Some Pagoda engines came with 5,000 K resistance ends and others with 1,000 K resistance ends, depending on year of manufacture, delivery with radio, factory electronic ignition etc. If in doubt about which your car came with, default to the 1,000K ends.

Nothing finishes off a nicely detailed engine like a correct looking and routed set of spark plug wires. Look at numerous pictures on this site and refer to numerous photos in the BBB of original wiring sets and routing.

Many of these cars still have the nice original ignition wiring still in place and working well, since the original solid wires seldom fail. Occasionally resistor ends must be replaced. Checking the wire sets with an ohm meter will keep things working.

Eminent · « **Reply #11 on:** July 28, 2012, 09:16:53 »

This week i replaced the wires for a new set form Beru.
The problem is not solved, still there are sparcs comming trough the isolation of the wires.
I'm stuck, i have no idea what could be wrong.

Dave · « **Reply #12 on:** July 28, 2012, 20:07:22 »

I have what looks like original wires. What ohm resistance number should I test for? Is the test one lead on one end of the wire, and the other lead at the other end, then read the ohms value on the meter?
thanks !

Eminent · « **Reply #13 on:** July 28, 2012, 22:22:30 »

Yes, test the resistance from one end of the cable to the other end. It should be about 1000 Ohm.

ja17 · « **Reply #14 on:** July 30, 2012, 04:44:40 »

Test from connector to connector and compare all six wires assemblies. A bad wire assembly will show up by having a lot more resistance than all the others. If you find one with a lot more resistance remove the connector ends and check each one. You will be able to identify the bad component.
Resistance may vary depending on the wire set on your car. Typically the end at the spark plug is either 5,000 ohm or 1,000 ohm, the end at the distributor may be another 1,000 ohm on the removable ends. The coil wire may also have 1,000 ohm removable ends.

Just do the comparison test first, the problem will be apparent if you have one. Calculating the exact ohm figures of each wire assembly is normally not needed.

enochbell · « **Reply #15 on:** August 04, 2012, 16:33:35 »

Parsimony: the economy in the use of means to an end. It is one of my favorite words.

But I violated it to the core! I can not believe how much time and effort I spent trying to solve the puzzle of my rough running problem. I pulled apart and tested every element of the WRD and TSV. I consecutively unplugged every connection. I tested fuel pressure EVERYWHERE. I lived with this problem for years. And the problem was as simple as bad wires.

I guess my point is, and I make it to myself above all, when a problem seems really complex look for a simple solution.

Got the car back today, it runs perfectly. And the old wires were Bosch and the new ones are Beru (thanks Dan).

Best,
g

Eminent · « **Reply #16 on:** August 04, 2012, 16:48:31 »

But what was wrong with the wires that they let the engine runs rough?
My problem is that there are sparcs passing by the insulation to the bodywork.
New Beru wires didn't solve the problem and now i don't know how to solve this.

Benz Dr. · « **Reply #17 on:** August 04, 2012, 20:05:08 »

I'm not positive about this, but I saw this yesterday on a 190SL which uses the same basic ignition system.

I saw sparks jumping across the coil from the tower to the negative lead. This engine was fouling plugs like crazy unil I emoved the carbs to have a look. Even though they were fresh rebuilds, the main jets were in backwards and it was over fueling the engine. I haven't tried the correction yet but Im sure it will work properly now.
Since the spark plugs were fouled, all of that energy had to go somewhere and it traveled to the best source of ground, which in this case happened to be the coil. At higher RPMS the fuel ratios are leaner and the plug may fire or at least enough that you wouldn't notice a miss. Maybe you should try a new set of spark plugs.
This why it can be so hard to start an engine with fouled plugs. The cold air, along with the dense mixture, will make the spark plug short out. Put a new clean set in and it will fire instantly provided there's nothing else wrong.

Eminent · « **Reply #18 on:** August 04, 2012, 21:48:39 »

Although the plugs are not that fouled (they looked brownish/grayish) it is worth the try. The NGK's BP5ES are not that expensive.
My car runs, and i don't know if you are familiar with that, on a fuel called LPG (GPL in some country's).
This is a mixture from butane and propane, it has a high octanenumber from about 105.
Maybe thats also a reason for a difficult spark at the plugs?
Anyhow, i'm gonna try new plugs and set the fuel mixture a bit leaner.
Fingers crossed.
Thanks Benz Dr.

Cees Klumper · « **Reply #19 on:** August 05, 2012, 05:26:42 »

I just read (in Auto Motor Klassiek) that cars that run on LPG need hotter than standard spark plugs. So give that a try because, if correct, that could explain why your car runs less well once warm. Good luck.

Eminent · « **Reply #20 on:** August 05, 2012, 09:48:12 »

Thanks Cees. Due to your answer i did some searching around the www, and all i read is that i should use a colder plug

For example in this article.
Are you sure that the article you read advise a hotter plug?
Thanks.

Cees Klumper · « **Reply #21 on:** August 05, 2012, 16:09:24 »

Sorry, no, I'm not sure, probably I remembered it backwards so 'colder' it is!

Eminent · « **Reply #22 on:** August 05, 2012, 20:23:48 »

Well, they all talk about the colder ones for LPG, so i'm gonna try that first.
Thanks for pointing me in that direction.

Benz Dr. · « **Reply #23 on:** August 05, 2012, 22:24:25 »

BP5ES is a hotter plug. I'm not sure if they make a 4 or not. If you want colder then I would try a BP6ES which crosses over to the old Bosch W7DC which in my opinion is too clod for most engines.
The problem is the car runs rich at idle and during warm up. This tends to foul out colder plugs but has less affect on this hotter plugs.

Eminent · « **Reply #24 on:** August 05, 2012, 22:29:19 »

If thats so i'll be better off with a colder plug indeed.
I only use gasoline to start, when the enigine is running i immediately switch over on LPG.

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Author Topic: ignition wires (Read 16318 times)

enochbell

Eminent

enochbell

enochbell

Eminent

Dave

Eminent

enochbell

Eminent

Eminent

Eminent

Eminent

Eminent