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Unread 05-27-2013, 01:50 PM   #1
bwillar1
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1989 YJ Wrangler 
 
Join Date: May 2013
Location: Scottsdale, AZ
Posts: 2
jeep yj streetfire msd install help

I have a 1989 jeep YJ with a 2.5L 4cyl engine, all stock. i recently bought a streetfire msd but im not sure how to install it. ive been trying to figure it out but im not really sure where to start. Im pretty much lost and any help would be appreciated.

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Unread 06-08-2013, 01:05 AM   #2
packdog
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2001 XJ Cherokee 
 
Join Date: Apr 2013
Location: Kelso, WA
Posts: 65
It should be easy

I will be installing a street fire in my 4.2 Jeep this weekend.

Basically you just follow the instructions that came with the MSD box. It gets hooked up to the battery positive and ground, and needs a wire that comes from the ignition switch to turn it on. Then depending on the rest of your setup it gets connected to the coil and distributor per the diagrams that came with it.
Then you need to figure out if you need the tach adapter or not.
It's really just a Nutter bypass on steroids!

The next steps depend on what carb you are using and how much of the emmissions you want to eliminate. Since it *can* replace the original ECU (but doesn't have to) you can disconnect all the wiring between it and the sensors under the hood. You will probably want to keep the wiring going to the gauges.
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Unread 06-08-2013, 02:10 AM   #3
OldSchoolRodz
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1993 YJ Wrangler 
 
Join Date: Oct 2007
Location: Marin, CA
Posts: 51
I'm in the same boat as Bwillar1.

Since Bwillar1 and I are both running 4 squirrels, maybe the questions I'm going to try to expand on will help him as well, without feeling like I've highjacked his thread .

The principle questions should be similar. Even though there are a couple minor differences in installation specifics.

Any additional feedback from a forum reader out there that has experience wit CA emissions compliance would be appreciated!

I'm installing an electronic ignition module that is essentially the same as the MSD made by Jacobs.

I live in CA and my Jeeps also a DD so it requires routine emissions testing, and my 4 banger is a 93 running OEM fuel injection,

The devils in the details; I need to understand;

1) How to leave enough fuel regulation and emission sensors intact to keep it emission legal Inc; Which sensors should stay connected to the original ECMU.

2) Understand the principles of this modification well enough that when I go in for emissions testing, I can illustrate for the inspection technician exactly why my Jeep's still in compliance.

For instance, is this a defendable assertion? "this ignition module is a minor modification designed to improve fuel efficiency, by improving the combustion of available fuel injected into the combustion chamber."

Thx gentlemen!

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93 YJ 2.5L on as much juice as lil 4 banger can handle, Sum New School Bump N Grind Guards, TJ Wheels N Fat Meats, Sum Old School Mojo[FONT="Comic Sans MS"][SIZE="4"][COLOR="Lime"][/COLOR][/SIZE][/FONT]
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Unread 06-08-2013, 08:54 AM   #4
packdog
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2001 XJ Cherokee 
 
Join Date: Apr 2013
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Can CA Nutter legally?

All the MSD box does is take the signal from the distributor and tell the coil when to fire. So in simplest terms all you do is cut the wires coming from the distributor and hook them to the MSD box, then disconnect the old coil power wires and hook it up to the MSD.

The stock system ECU uses the output signal of the distributor (along with inputs from the other sensors) to control the ignition timing (and other emissions devices).

When non emissions testing folks Nutter or install MSD boxes the ECU no longer gets the distributor input signal and can no longer make the decisions it used to to control the system. The ignition timing is then determined solely by vacuum and mechanical advance. depending on what year the Jeep is this can confuse the ECU to varying degrees. Older ones usually ignore it and just keep running. Newer ones might light the check engine light and/or go into "limp home mode".

In order to meet emissions testing you will need to figure out a way to keep sending the distributor signal to the ECU. You might be able to keep the original wiring to it and just tie in the MSD (running in parallel) so that they both get that signal.

No idea if anything I've mentioned would meet emissions or not, especially in CA.
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Unread 06-09-2013, 12:15 AM   #5
OldSchoolRodz
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1993 YJ Wrangler 
 
Join Date: Oct 2007
Location: Marin, CA
Posts: 51
Ignition modules

Thx Packdog.

That was a helpfull response... That clarifies things a bit, where there's a will there's a way!
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93 YJ 2.5L on as much juice as lil 4 banger can handle, Sum New School Bump N Grind Guards, TJ Wheels N Fat Meats, Sum Old School Mojo[FONT="Comic Sans MS"][SIZE="4"][COLOR="Lime"][/COLOR][/SIZE][/FONT]
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Unread 06-09-2013, 03:19 AM   #6
BigDub
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1989 YJ Wrangler 
 
Join Date: Jan 2013
Location: Mobile, AL
Posts: 12
Quote:
Originally Posted by packdog View Post
I will be installing a street fire in my 4.2 Jeep this weekend.

Basically you just follow the instructions that came with the MSD box. It gets hooked up to the battery positive and ground, and needs a wire that comes from the ignition switch to turn it on. Then depending on the rest of your setup it gets connected to the coil and distributor per the diagrams that came with it.
Then you need to figure out if you need the tach adapter or not.
It's really just a Nutter bypass on steroids!

The next steps depend on what carb you are using and how much of the emmissions you want to eliminate. Since it *can* replace the original ECU (but doesn't have to) you can disconnect all the wiring between it and the sensors under the hood. You will probably want to keep the wiring going to the gauges.
I used the Summit Racing clone for my 4.2, couldn't be happier.
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Unread 06-09-2013, 05:20 AM   #7
jay-h
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1989 YJ Wrangler 
 
Join Date: Dec 2006
Location: , NJ
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Quote:
Originally Posted by OldSchoolRodz View Post
Thx Packdog.

That was a helpfull response... That clarifies things a bit, where there's a will there's a way!
I guess it's obvious, but you can't, however eliminate the ECU on the 2.5, in fact there is nothing you can easily change there except using the MSD to provide more consistent spark.
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Unread 06-13-2013, 08:54 PM   #8
bwillar1
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1989 YJ Wrangler 
 
Join Date: May 2013
Location: Scottsdale, AZ
Posts: 2
after calling msd 3 times i was finally able to get the correct answer. inorder to install a msd on a 2.5L you need to get wiring harness 8813 aswell as the tach adaptor. however they dont sell it anymore. so if you cant find it online heres the instructions its pretty easy to replicate: http://www.jegs.com/InstallationInst...1/121-8813.pdf . you may experience engine run on so make sure you have the diode.

Last edited by bwillar1; 06-13-2013 at 10:43 PM..
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