mazing3

Hi Folks,

The car is a 78.

I've been wrestling with a random no start to sometimes starts issue for a month now. The past week has been no start. Went in pretty deep on it this time checking, replacing things, testing things until 2 days ago I triumphed and off I went happily driving. No problems, no issues and quite frankly it ran better than it ever has. Been that way for 2 days. Yesterday, once I got it up to temp, I did a little adjusting with the AF and Idle with the help of my wide band and drove it home.

Today- back to no start. I did have a little leakage on the return line of the WUR but took care of that. It does turn over and ignite but all I get is a nice hearty VROOM and then dies. This "VROOM to dead" phenomenon has been the primary symptom for my starting issues for about a month now. I've had 3 different green wires in there too.

As I was going through all of this originally I went through the Ignition trouble shooting in the WSM and this leads me to the Ballast Resistors and my questions.

Both out of spec-

.4ohm resistor reading .9ohm (.35-.45 is spec range in WSM)
.6ohm resistor reading .8ohm (.55-.65 being in spec)

So what do these things do exactly? All I could find was that they keep out radio noise? Is that accurate?

Can I just delete them and bypass the wiring to the coil and drive until I can get some new ones?

and most importantly... can these things be playing a role in my starting woes? It appears something is getting progressively worse in my system becoming more unpredictable. The "VROOM-Dead" is the most consistent symptom. By the nature of the fact that they heat up while driving, is it reasonable to think that heat cycle could be exacerbating the problem?

I'm at a loss here.

Thank you for your advice and suggestions in advance!

Robbie
78 928 5spd

vze2jshn

You might try to source a reasonably priced used "spark box" through our colleagues here on rennlist. The boxes seldom fail but after years of intermittent starting problems and troubleshooting, I bought a used box for $60 and the problem went away.

Mark Anderson

if you do end up needing the resistor we carry them
http://shop.928intl.com/Series-Resis...o/046-905-109/

James Bailey

If you feed a full 12 v to the coil it will overheat boil the tar/oil and blow the end off the coil leaving a bunch of tar on the inner fender....took me about 30 minutes on a hot day . Fortunately I had a spare coil with me

mazing3

Thanks Greg!
I thought about that too at one point but in this case it's not the case....


Thanks Mark- I'll order some up tomorrow because------->

I FIXED IT! It was indeed the ballasts causing this problem. Note to self- when doing a search for something here it really seems to make a big difference if you call it the right name. :-))

Jumped the ballasts and it Fired right up! I gotta track that guy down and PM him a beer.

Now this makes all kinds of other weird things that were going on make sense now!

I guess having a ballast set making up the rules randomly is not a good thing at all.

Thanks Rennlist!

Robbie
78 5spd

mazing3

thanks James- What do you think would happen if I just jumped the .4 since it was the one most outta whack of the 2? Assuming that will allow it to still start.

I need to make a 40 minute drive to someplace local that I know will have a couple before I can get the new ones delivered.

Thanks

Robbie
78 5spd

James Bailey

I only recommend doing it for a very short time but you probably will get away with it I think I drove about 45 minutes on the second coil going home with no problems as it was at night and not bumper to bumper traffic.....

VanD

Sounds like it could also be a green wire issue. If the problem persists change it as well. Your symptoms sound very familiar.

LT Texan

Weird that these resistors drifted so far out of spec.

linderpat

someone elighten me on these resistors. Where are they located?

mazing3

Thanks James- duly noted for sure. I don't want to see what the inside of a coil looks like.

Alex- I've been through 2 green wire replacements thinking that was the issue as well... The thing started on the first try after jumping the resistors. So who knows. I haven't tried actually driving yet though so there may be more to come on the story but just getting it started and running was the primary mission- again, it did all that just fine for the past 2 days-until today.

Dan- I was kind of thinking the same thing. I just don't know what to make of it yet. But at the same time, nothing on this car really surprises me much anymore after all of the other mysteries I have uncovered.

Thanks guys. I'll let you know how driving tomorrow actually goes.

mazing3

Ed- not sure if you are joking or not... :-) I'm talking about the pair on the left fender behind the PS reservoir.

crushingday

I want to know this as well.

Also, can I measure it with a Multimeter?

mazing3

yeah you can, but they are not particularly easy to reach. There is 1 10mm bolt that holds them mounted up. I wound up just taking that out and pulled everything up for a better look.

crushingday

Thanks mazing3. Can you tell where where it/they are located? I have a '78