TR upgrade question... - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

Reply
 
LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 07-06-2001, 04:00 PM Thread Starter
 
Join Date: Jun 2000
Posts: 526
Thanks: 0
Thanked 0 Times in 0 Posts
 
TR upgrade question...

OK, What's the real scoop? Do I or do I not need the resistor on the firewall that I used with my old ignition? The instructions said to use it, but I read recently to eliminate it. Which way works better?
Thanks.



'86 CJ-7, 360, TFI, 727, OEM Dana 44 rear w/Truetrac, Dana 30 w/Powertrax No-Slip, 4" Superlift, 4:11s, Warn HS9500i
BillR is offline  
Sponsored Links
Advertisement
 
post #2 of (permalink) Old 07-06-2001, 05:18 PM
Keyboard Implanted
 
jeepgod's Avatar
 
Join Date: Jan 2000
Location: Wildomar, CA
Posts: 4,618
Thanks: 0
Thanked 3 Times in 3 Posts
 
Re: TR upgrade question...

mmm.. the instructions i have.. say.. NO resistor.. that the tfi coil takes all 12 volts..

any ford guru's here.. i am about to put it on mine this weekend.. if the junkyards around here ever open up.. jeesh.. youd think it was a holiday or somethin...

http://www.jeepgod.net

84 CJ-7 401/T-18/D20/D44/D60w/4.10&Detriots/YJ frame & tub/35x16x15 Boggers
<font color=orange>survival is instinct, but living takes guts</font color=orange>
jeepgod is offline  
post #3 of (permalink) Old 07-06-2001, 05:34 PM
Way Outta Control
 
Join Date: Sep 1999
Location: The Palouse
Posts: 13,432
Thanks: 1
Thanked 3 Times in 3 Posts
 
Re: TR upgrade question...

Bill, and Jeepgod... your questions and answers are good...however there seem to be mixed results in coil longevity using the full 12 volts to the coil. A TFI coil is engineered to be used with the FOMOCO TFI ignition system. The OEM Jeep FOMOCO system uses a different ignition module and distributor. This raises questions about pulse time, width and TFI coil saturation using the OEM Jeep FOMOCO ignition module. I believe this is where the variance occurs. If the module produces a wider, longer lasting pulse the coil become saturated for a longer time. There is little time for the coil to cool before the next pulse. This leads to premature failure. Another ignition module (AutoZone, Pepboys, etc.) may produce a shorter pulse and the timing works out OK. This does not burn up the coil. Like my kids are fond of saying: "It's the same thing, only different." I don't have the insturmentation or the desire to do follow up on this question so I'll just stick to my GM HEI ignition.

LEVE is offline  
Sponsored Links
Advertisement
 
post #4 of (permalink) Old 07-06-2001, 06:17 PM
Old Hand
 
Join Date: Feb 2000
Location: Western New York
Posts: 839
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: TR upgrade question...

Mine has been running for about a year now and has the resistor in it. The voltage at the coil is about 4.6 volts

lindy80cj7 is offline  
post #5 of (permalink) Old 07-06-2001, 08:07 PM
Keyboard Implanted
 
jeepgod's Avatar
 
Join Date: Jan 2000
Location: Wildomar, CA
Posts: 4,618
Thanks: 0
Thanked 3 Times in 3 Posts
 
Re: TR upgrade question...

ok.. so you are running.. 4.6 volts.. mmmm.. Elusive is running the full 12 volts in his.. and they are not lasting.. but a month maybe..
and i understand what you are getting at leve.. mmmmm... ill will some drinkin tonight.. and some thinkin.. and maybe some research this weekend... if im not that hungover.. [img]/wwwthreads_images/icons/laugh.gif[/img]..
ill see what i can dig up.. and expeirment with..

http://www.jeepgod.net

84 CJ-7 401/T-18/D20/D44/D60w/4.10&Detriots/YJ frame & tub/35x16x15 Boggers
<font color=orange>survival is instinct, but living takes guts</font color=orange>
jeepgod is offline  
post #6 of (permalink) Old 07-06-2001, 08:20 PM
Way Outta Control
 
Join Date: Sep 1999
Location: The Palouse
Posts: 13,432
Thanks: 1
Thanked 3 Times in 3 Posts
 
Re: TR upgrade question...

lindy80cj7, 4.7 DC volts does seem very a low coil voltage. I'd be happier with it being between 8.2 and 8.9 DC volts. If you're using a resistor, try replacing it with one of a smaller ohm value. The smaller the ohm value will result in a larger voltage to the coil.

If the resistor is in the form of resistor wire then cut out about 1/3 of it's length. That should bring up the voltage to about the correct voltage.

It is true that with the higher voltage to the coil, a higher spark output will result from the coil.

Jeepgod, let me know what you come up with. If Elusive's using the full 12 volts and the coil is not surviving, then the problem is clear.... full voltage is killing the coil. Resistance should be placed in series with the coil to cut down the voltage to the coil.

LEVE is offline  
post #7 of (permalink) Old 07-06-2001, 11:36 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: TR upgrade question...

jeepgod,
Your instructions may say no resistor because the stock positive coil wire is already a resistor wire. If it has been replaced, then yes a ballast resistor is necessary. Elusive will have better luck with coils if he would step it down to about 8.5 to 8.9 volts.

'75 CJ5,258 w/Howell EFI,T18a,4.27's,33's,On-board air,Warn 8274
post #8 of (permalink) Old 07-07-2001, 08:01 AM
Keyboard Implanted
 
jeepgod's Avatar
 
Join Date: Jan 2000
Location: Wildomar, CA
Posts: 4,618
Thanks: 0
Thanked 3 Times in 3 Posts
 
Re: TR upgrade question...

ok.. ya.. i took out that resistor wire long ago.. when i went back to running points on an old I6... so now i just have the ballast resistor in....

http://www.jeepgod.net

84 CJ-7 401/T-18/D20/D44/D60w/4.10&Detriots/YJ frame & tub/35x16x15 Boggers
<font color=orange>survival is instinct, but living takes guts</font color=orange>
jeepgod is offline  
post #9 of (permalink) Old 07-07-2001, 12:57 PM Thread Starter
 
Join Date: Jun 2000
Posts: 526
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: TR upgrade question...

I took the ballast resistor out of the circut, and didn't notice any difference in starting or acceleration. I just re-installed it back into the system to help the coil last longer.
BTW, I'm getting about 5.2 volts at the coil at key-on and around 10.5 volts while running. Does this sound about right?


'86 CJ-7, 360, TFI, 727, OEM Dana 44 rear w/Truetrac, Dana 30 w/Powertrax No-Slip, 4" Superlift, 4:11s, Warn HS9500i
BillR is offline  
post #10 of (permalink) Old 07-07-2001, 11:43 PM
Way Outta Control
 
Join Date: Sep 1999
Location: The Palouse
Posts: 13,432
Thanks: 1
Thanked 3 Times in 3 Posts
 
Re: TR upgrade question...

Bill, it seems something is not quite right.

Ususally in the START mode full 12 volts are applied to the coil. This gives the hotter spark and aids in starting a cold vehicle.

When in RUN mode the voltage is lowered to between 8 and 9 volts to pereserve the coil.

LEVE is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome