plugs 3 & 4 not producing spark

Hi,

this is my second attempt at posting this question. Hopefully it takes this time.

My non-running (for a very long time) 1979 KZ1300-A1 has an issue with plugs 3 & 4 not producing any spark. I removed the blue & pink connections and instead put the black & pink connectors (for plugs 1 an 6) on the coil for plugs 3&4. Low. and behold, I got spark, so clearly the coil itself isn't the problem.

So what's left. Is it the IC Ingniter?  If so do they still have a replacement available?  

thanks

giorgi3 wrote: Hi,

this is my second attempt at posting this question. Hopefully it takes this time.

My non-running (for a very long time) 1979 KZ1300-A1 has an issue with plugs 3 & 4 not producing any spark. I removed the blue & pink connections and instead put the black & pink connectors (for plugs 1 an 6) on the coil for plugs 3&4. Low. and behold, I got spark, so clearly the coil itself isn't the problem.

So what's left. Is it the IC Ingniter?  If so do they still have a replacement available?  

thanks

IMHO - I always like to pick on the ballast resistor since it's a resistance filiment which absorbs energy (voltage) and turns it into heat to dissapate that energy. Old ballast resistors will burn out like light bulb filaments. So first thing I would do is check the resistance across the ballast resistor. I suspect 2 of the resistors are fine and the third is open circuit.

If that's not the case, then check the pulser coils and check the wiring connections between the pulser coils and the IC  ignitor.

Unless somebody's done something stupid with the coils and changed them out for low resistance coils, I doubt that the IC unit is at fault.  Too many times we've seen issues with corroded connections. 

My betting money is on the ballast resistor.

Kawboy a quick question about the ol' ballasts, have you ever seen the construction of the the resistance element in the ceramic bodies?

I've just been searching for some 0.4 ohm jobbies for my 2.2(ish) ohm AW82s and looks like the Beru / Merc one used by folks on here is the only thing I can get in the UK, albeit pricey and surprisingly difficult to find stock (now suss'd after hunting through suppliers of old Merc parts)

This got me wondering what the internal construction is, as what are very readily available and 10 times cheaper are the aluminium finned wire-wound types, but I'm not sure if wire-wound might act like a huuuge inductor and slow down the current change rates / coil charge times and mess up the whole concept?

I guess there's then the whole point about (lets say 15 watts average) through a ceramic housing, versus the same through a metal housing, and whether the ally presents as a hotter / riskier thing.

Any thoughts?

RChaloner wrote: Kawboy a quick question about the ol' ballasts, have you ever seen the construction of the the resistance element in the ceramic bodies?

I've just been searching for some 0.4 ohm jobbies for my 2.2(ish) ohm AW82s and looks like the Beru / Merc one used by folks on here is the only thing I can get in the UK, albeit pricey and surprisingly difficult to find stock (now suss'd after hunting through suppliers of old Merc parts)

This got me wondering what the internal construction is, as what are very readily available and 10 times cheaper are the aluminium finned wire-wound types, but I'm not sure if wire-wound might act like a huuuge inductor and slow down the current change rates / coil charge times and mess up the whole concept?

I guess there's then the whole point about (lets say 15 watts average) through a ceramic housing, versus the same through a metal housing, and whether the ally presents as a hotter / riskier thing.

Any thoughts?

Internal construction - It's a piece of stainless steel wire wound up like a light bulb filament and then set in a ceramic housing to dissapate heat. Depending on the required resistance, the wire is either longer or shorter. The more resistance of the ballast, the more heat must be dissapated.

Those metal canned ballasts I believe are for stereo equipment and I'm not sure if by design they are for DC current or AC. I would shy away from them.

If you're using the aftermarket AW82's then you should source out the ballasts from the older Mercedes 450 SL 280 SL  They are still available and are .6 ohm  .6 ohm resistor Bosch part # 0 227 901 013  I've added this link for reference only. On the 3rd picture in the link you'll see the 0.6 stamped in the aluminum bracket which indicates the resistance of the ballast and  the 4th picture shows the Bosch part #.   

I'm pretty sure I sourced these out for around $20 Canadian. Can't remember where. Had it in the back of my mind that I found them at NAPA auto parts. Not too bad.

Hi Kawboy,

Here is a picture of the ballast resistor before I pulled the wires off.

I pulled the 3 pink wires and the yellow wire off of the ballast resistor and set my Ohm meter to the smallest setting (200). . Connecting from the tab that had the yellow lead on it to each of the 3 pink tabs on the ballast resistor itself, I show a resistance of 2.1 on each.  The manual says 1.5 - 1.9 ohms but that could be my cheap-o meter?

Anyway to further check, I pulled the blue wire back off the coil and placed the black wire back on in it's place. I didn't change the pink wire at all, and I now have spark coming from plugs 3-4. 

So I'm guessing the resistor is 'ok'?

Thoughts?




   

 I can't recall ever seeing a  post that definitively stated a ballast-resistor had failed.  They're robust  and seemingly bullet-proof compared to the fine-wire winding's in a trigger.   The enclosed/very hot environment the 3 triggers must operate/survive in will create expansion contraction conditions that can cause an "Open" failure.  Had one fail many years ago.  When it got hot it quit working.  Let it cool down for only a few minutes and it would work again....... Until it failed 100%   
My money is on the ignition-trigger. 

Insert: Audio of "Jeopardy" final round!