TheSamba.com :: View topic - resistance of blue coil -solved-

Wed Aug 27, 2008 4:10 pm

yeah... engine decided to develope another problem..

car looses power, acts like it wants to pull, starts to pull, ETC back and forth.

im sure its the coil or condensor, as the TACH jumps like crazy when the car acts up.

might i add, it only seems to do this when under heavy load, IE full throttle.

no popping, or backfiring. just looses power, you HAVE to drive it VERY easy or else it acts up.

a search brought up coil properties.
i tested the coil across pos and neg, for 4 ohms. pos to center hole, 13,433 ohms.

ive heard when coils die, that they just die striaght out. is it the condensor? any ideas? :x

Wed Aug 27, 2008 4:47 pm

dog_jr911 wrote:

a search brought up coil properties.
i tested the coil across pos and neg, for 4 ohms. pos to center hole, 13,433 ohms.

Don't have exact specs right in front of me, but that's about right.....

Dale

Wed Aug 27, 2008 4:50 pm

thats what i was thinking, stock coils where like 13000.

ive had this happen three times.

once it was fouling plugs
once it was the cap
once was the condensor

im going to try a new condensor, im 90% sure thats what it is.

hopefully its a ten dollar problem [-o<

Wed Aug 27, 2008 7:54 pm

not sure if this helps but the non bosch ones that you get at an auto parts store are sposed to be between 6.5k-9.5k ohms 13k seems kinda high

Wed Aug 27, 2008 8:17 pm

The Bosch blue coil that I have has a primary resistance of 2.93 ohms and a secondary resistance 10,463 ohms. It's not uncommon for the secondary resistance to vary. The wire is very thin and can stretch during the winding process. When the wire stretches, it's resistance increases. Also, it's not uncommon for manufactures not to have very good control of their winding process for non-critical applications. As an example, they may just fill a bobbin full of wire instead of winding the exact number of turns of wire.

While ignition coils often fail outright, it's not impossible for one to become weak.

Direct substitution with another ignition coil is usually the easiest and best way to troubleshoot the problem.

If the Bosch Blue coil is in fact bad, you might come to your senses and replace it with an air gapped core ignition coil.

Scott Novak

Thu Aug 28, 2008 2:18 am

Scott Novak wrote: If the Bosch Blue coil is in fact bad, you might come to your senses and replace it with an air gapped core ignition coil.

Actually, he already came to his senses and went with EDIS distributorless programmable ignition. :wink:

Thu Aug 28, 2008 4:52 am

miniman82 wrote: Scott Novak wrote: If the Bosch Blue coil is in fact bad, you might come to your senses and replace it with an air gapped core ignition coil.
Actually, he already came to his senses and went with EDIS distributorless programmable ignition. :wink:
It sure seems like he is talking about a Bosch blue coil and a distributor with points and a condenser to me.

Full throttle conditions increase the fuel mixture density inside the combustion chamber and raise the ionization voltage of the spark plug gap. So if your ignition is really weak for whatever the reason, your engine may idle, but have problems when you try to accelerate. If you have spare parts laying around, swapping them in is the fastest way to troubleshoot the problem.

It could be the condenser, or it could be arcing inside the ignition coil as the voltage inside the coil becomes higher during full throttle conditions. I've also seen bad factory crimp connections on the wire to the breaker points that caused an intermittent failure.

Scott Novak

Thu Aug 28, 2008 5:13 am

I should have said 'will go' with EDIS. This is all temporary till he gets off his duff to do the EFI install, which will involve EDIS.

Thu Aug 28, 2008 6:08 am

Whatever ignition system Dog ends up with, he should be using air gapped core ignition coils, whether they are Jacobs or some other brand.

Scott Novak

Thu Aug 28, 2008 6:25 am

dog_jr911 wrote: im sure its the coil or condensor, as the TACH jumps like crazy when the car acts up.

It's the coil, I had a brand new Bosch Blue (Yes, the good German one, possible a dud) that made the tach jump wildly. I tried different condesors, tachometer, diodes inline with the tach, wires, distributors... nothing helped, swapped the coil and the tach was dead on.

Thu Aug 28, 2008 2:40 pm

hmm ok, i couldnt get the condensor yesterday.

ive been trying to experiment as to what causes the problem. i found that-

it doesnt do it right away.
almost always happens in forth gear.
is COMPLETELY RANDOM.
pissing me off....

ill see if i can borrow my niehbors coil, or something.....

its just odd that its not consistant in any means.

ill try the coil first, parts store sells some black off-brand coil.

scott... ill see if it has an air-gapped core :wink:

and yes, i have a EFI setup in-the-works. its just sitting....still. gotta paint my car first!

Thu Aug 28, 2008 3:13 pm

Make sure that you have a total ballast resistance of at least 3 ohms or you might burn out he ignition coil! You may need to buy an external ballast resistor. By that I mean that the total of the coil's primary resistance and any external ballast resistance must be at least 3 ohms.

Scott Novak

Thu Aug 28, 2008 3:16 pm

i dont think i have a resistor on my engine... :?

ill make sure the coil is interna;;y resisted.

Thu Aug 28, 2008 3:21 pm

The stock VW coil has a built in ballast resistor. The Bosch blue coils that are sold for air cooled VWs also have a built in ballast resistance. However, not all Bosch blue coils have built in ballast resistors. Every so often someone installs one of these on their VW without an external ballast resistor and burns up the coil.

BTW, good luck asking a parts guy if their ignition coils are air gapped. Don't be surprised if you get an empty stare and a "HUH"?

Scott Novak

Thu Aug 28, 2008 4:07 pm

Scott Novak wrote: The stock VW coil has a built in ballast resistor. The Bosch blue coils that are sold for air cooled VWs also have a built in ballast resistance. However, not all Bosch blue coils have built in ballast resistors. Every so often someone installs one of these on their VW without an external ballast resistor and burns up the coil.

BTW, good luck asking a parts guy if their ignition coils are air gapped. Don't be surprised if you get an empty stare and a "HUH"?

Scott Novak

thats EXACTLY his reaction! lol.

ALRIGHT!! the problem IS STILL LIVING.
so my old coil was fine......

how else can i describe it.... it fire for about half a second, blubbers for half a second... over and over. happens in fourth or third it seems, when you hit the throttle hard, or try to accelerate... sometimes.

a few days ago i had a needle valve get stuck open... maybe its getting stuck closed now?

can you lubricate a needle valve?

Thu Aug 28, 2008 4:39 pm

Make sure the connections are clean and tight....I had kinda the same problem once, ran fine until I tried to rap it out, then it would cut out/ miss badly. I changed the coil, dist. wires....turned out to be a loose connection on the coil. Probably not it, but worth a look. Joe

Thu Aug 28, 2008 4:45 pm

well i went and brushed all the connections, still acts up pretty bad.

im going to go thru the carbs.. just to be sure. maybe its getting dry?

Thu Aug 28, 2008 6:24 pm

Sounds more like a dist. advance or a fuel problem, and not a coil...

And usually a BOSH Blue that is labeled 12 VOLTS does NOT require a ballast resistor....

Dale

Thu Aug 28, 2008 6:37 pm

yea, im thinking its the right PDSIT carb, i had a needle valve issue last week, it was stuck open and flooded the engine. maybe its getting stuck closed?

how can i lubricate the valve? wd-40?
oil?

Thu Aug 28, 2008 6:39 pm

Have you tried it without the tach hooked up? Back before you were born I had an issue that was similar to yours and it turned out to be the Tach...

A long shot, but cost nothing to try...