Notices
928 Forum
Sponsored by:
Sponsored by: 928 Specialists

Green ignition wire

 
Old 01-17-2019, 08:28 AM
  #46  
WALTSTAR
Addict
Rennlist Member
 
WALTSTAR's Avatar
 
Join Date: Dec 2012
Location: NEW YORK
Posts: 544
Default

Originally Posted by Hacker-Pschorr View Post
I get that, but I've been down this road way too many times. So it's got a running issue (pick any) build your own green wire, problem doesn't go away "Great, it wasn't the wire!"...maybe.
I've worked on these cars where a "known good" used green wire was installed to eliminate that possibility. After many, many hours later of trying to track down the issue a new green wire was installed. Poof, problem solved.
Bonus fun: The previous car which "donated" the green wire never had this issue.

We're not talking thousands of dollars, it's $140 for something that should last another 25+ years and is the lifeblood of the ignition system.

Any running issue going forward that wire will be suspect. It's not worth the hassle or headache.



With your comment I wonder if the new wires are longer than before. When I installed a new one in my 79 there was so much slack I too zip tied it to the cross brace to get it out of the way.
.....Exactly that....Why bundle it all up against the engine?
WALTSTAR is offline  
Old 01-22-2019, 12:51 AM
  #47  
Dylan_928
User
Thread Starter
 
Join Date: Oct 2018
Posts: 54
Default



here is a mock-up i made myself just in case. Might try hooking her up, but probably not. Im expecting a green package tomorrow morning. (Today). Cross your fingers that it works
Dylan_928 is offline  
Old 01-22-2019, 06:08 PM
  #48  
dr bob
Chronic Tool Dropper
Lifetime Rennlist
Member
 
dr bob's Avatar
 
Join Date: Oct 2001
Location: Bend, Oregon
Posts: 17,603
Default

You used what looks like 75 ohm TV coax. The green wire is actually "twin-ax", with two separate conductors running inside the shield. The "coil" in the distributor is actually a Hall sensor, watching as the "teeth" on the ferrous "reluctor" pass by. The signal from the sensor is pretty small, so almost any interference or magnetic/inductive coupling to the signal wires will confuse the ignition box. Shielding both is the only available answer. FWIW, it seems that the connectors are the failure point. The plastic gets crispy and brown.
dr bob is offline  
Old 01-22-2019, 09:03 PM
  #49  
Dylan_928
User
Thread Starter
 
Join Date: Oct 2018
Posts: 54
Default


just received wire today!! Thank you so much nate!!!
Dylan_928 is offline  
Old 01-22-2019, 10:47 PM
  #50  
GT6ixer
Addict
Rennlist Member
 
GT6ixer's Avatar
 
Join Date: Mar 2016
Location: Seattle. WA
Posts: 2,838
Default

Originally Posted by Dylan_928 View Post

just received wire today!! Thank you so much nate!!!
Glad to help out. Keep up the good fight!
GT6ixer is offline  
Old 01-23-2019, 01:05 PM
  #51  
docmirror
Shameful Thread Killer
Rennlist Member
 
docmirror's Avatar
 
Join Date: Aug 2004
Location: Rep of Texas, N NM, Rockies, SoCal
Posts: 19,441
Default

Originally Posted by dr bob View Post
You used what looks like 75 ohm TV coax. The green wire is actually "twin-ax", with two separate conductors running inside the shield. The "coil" in the distributor is actually a Hall sensor, watching as the "teeth" on the ferrous "reluctor" pass by. The signal from the sensor is pretty small, so almost any interference or magnetic/inductive coupling to the signal wires will confuse the ignition box. Shielding both is the only available answer. FWIW, it seems that the connectors are the failure point. The plastic gets crispy and brown.
I don't want to be a noodge, but the one's I've seen(which are few), and the 928 print show it as coaxial. Single center conductor with a shield. Pin A from the sensor to pin 7 of the ign module, and pin B from the sensor as shield to pin 31d of the ign module. Twinax (not "twin-ax") is two conductors, with a braid shield. I don't know the impedance of the coax, but if it's not 75ohm, I would be surprised. Common impedance for almost all coax applications, but it could be 50ohm.

https://forum.digikey.com/t/coax-twi...iax-cables/886
docmirror is offline  
Old 01-23-2019, 01:54 PM
  #52  
dr bob
Chronic Tool Dropper
Lifetime Rennlist
Member
 
dr bob's Avatar
 
Join Date: Oct 2001
Location: Bend, Oregon
Posts: 17,603
Default

My memory must be from a different car. Sorry!
dr bob is offline  
Old 01-25-2019, 01:33 AM
  #53  
Regularstormy
User
 
Join Date: Dec 2018
Location: Enid, OK
Posts: 8
Default

Is it possible to change to a different type hall sensor? I'm not sure the input to the ignition control, but a more common sensor could alleviate the need for the special connector
Regularstormy is offline  
Old 01-25-2019, 01:44 AM
  #54  
Hey_Allen
Addict
Rennlist Member
 
Join Date: Jul 2018
Location: Pacific Northwest, USA
Posts: 163
Default

I don't know for certain, but I suspect it is the ignition control module, more than the VR sensor in the distributor, that is being picky.
If it were a Hall sensor like later cars use, it would likely be far less of a pain, but with the technology used when these were built, that's a different matter.
Hey_Allen is offline  
Old 01-25-2019, 06:20 AM
  #55  
Landseer
Addict
Rennlist Member
 
Landseer's Avatar
 
Join Date: Sep 2007
Location: Frederick, Maryland
Posts: 11,262
Default

Let us know if it worked --- was the car ever running for you? Or are you bringing it back from being dormant?

I have an 84 16V USA car with an intermittently bad ECU that caused me all kinds of problems. Long story short, swapping it with a loaner proved the source of the problem.

There is tribal knowledge here that can both help and get in the way. I drank the koolaid, and maybe espoused it myself to others a few times, that the controller was bullet proof and would not ever fail. Turned out wrong.

I've also witnessed an incredible "save" a couple years ago whereby the pickup wasn't bad, but it had become unpinned from the distributor shaft. Once that got figured out all was good.
Landseer is offline  
Old 01-25-2019, 11:17 AM
  #56  
Dylan_928
User
Thread Starter
 
Join Date: Oct 2018
Posts: 54
Default

Originally Posted by Landseer View Post
Let us know if it worked --- was the car ever running for you? Or are you bringing it back from being dormant?

I have an 84 16V USA car with an intermittently bad ECU that caused me all kinds of problems. Long story short, swapping it with a loaner proved the source of the problem.

There is tribal knowledge here that can both help and get in the way. I drank the koolaid, and maybe espoused it myself to others a few times, that the controller was bullet proof and would not ever fail. Turned out wrong.

I've also witnessed an incredible "save" a couple years ago whereby the pickup wasn't bad, but it had become unpinned from the distributor shaft. Once that got figured out all was good.
the car had been running intermittently. I drove it to the gas station once, and it drove fine. Shut her off when i was fueling, got back in and drive home. Next day she wont start. I figured that the injectors were clogged so i pulled them and cleaned them out. Put them back in and she started fine. Next day she wont start. Now that i have exerything reinstalled i realized i timed the car to the exhaust stroke (im an idiot for that). Im crossing my fingers that the new wire works once i get the timing fixed.
Dylan_928 is offline  
Old 01-25-2019, 11:17 AM
  #57  
Dylan_928
User
Thread Starter
 
Join Date: Oct 2018
Posts: 54
Default

I will be giving updates as soon as i find anything out
Dylan_928 is offline  
 


Thread Tools
Search this Thread

Contact Us - About Us - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: