switching 258CI from carb to FI?

switching 258CI from carb to FI?
seanmnew

seanmnew

Jeeper
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Location
Colorado Springs
Vehicle(s)
86 CJ7 & 06 Liberty Sport
I have an 86 CJ7 , its got the AMC 258 i6 / 4.2l w/ 2bbl, I currently live in colorado springs, i live at 6300ft, and do most of my wheeling at 9000-11000ft, this carb is pissing me off, when i go up any steep hills it loves to flood out and die, which is not good... i dont dig going down steep hills in the middle of nowhere backwards! I want to change this over to a better setup, thinking FI would be the best way, any words of advice? Im open to any and all options. thanks
 
Mopar has an option for this I think TBI for about a grand. I think I would try a motorcraft upgrade with altitude compensation just for the heck of it. You may even try rebuilding the carb you have. I agree, if you think going up is fun try coming back down backwards. I have on ocation thought how lucky I was not to have power brakes and steering, that could be really exciting with a stalled engine. Keep us posted, this should be interesting.:popcorn:
 
There is all kinds of ways to get efi, but the bottom line is JUST DO IT you won't be sorry. (best upgrade I've made)
The cheapest way would be a junk yard tbi unit from a chevy 4.3
Another way would be aftermarket such as Howell
Some people use the jeep 4.0 setup
Google can be your friend on this one, lots of write ups out there
 
You wont regret switching!! I've got the Mopar MPI on my 8, huge difference!
 
I just read the busted Jeep site. that is an absolutely incredible job of illustrating the project. somebody buy that boy a beer!!:beer:

I'm sure that I just need more caffeine and all things will become clear but I did not see any mention of a crank position sensor. Is it not needed with the Chevrolet TBI??
 
ok, so i did a lot of looking into the 4.3 TBI, looks like a great idea, i did however find an O2 sensor and a few other things... my Chiltons wiring diagram however does not match my ECM, the one i have says "JEEP MCU SUPER-D MODEL NUMBER: 53005523"... and on the reverse side is a FORD stamp... my engine has a huge cluster of wiring harnesses that are not hooked up... im trying to get to the bottom of this and cant find any info, does anyone have any leads? whats the factory ECM for the 86 CJ7 ?
 
actually that sounds like the right ECM, it would be a ford part, but I would call my local parts house, I bet they even have one in stock. you don't have to buy it to look at it.
 
well it turns out it IS the right one... there is a mess of wires in my engine bay, about 10 unplugged harnesses and just wierd random wires (23 years of rednecks! (and going!))... but its horrible... I have been thinking about re-wiring it, now i have never re-wired a vehicle... but if i buy the complete harness and try and put it in do you think i should have any issues? the CJ seems pretty simple, i have been wanting to do this anyway and it would just be one step closer to making it easier on myself!
 
IOPort51 said:
I just read the busted Jeep site. that is an absolutely incredible job of illustrating the project. somebody buy that boy a beer!!:beer:

I'm sure that I just need more caffeine and all things will become clear but I did not see any mention of a crank position sensor. Is it not needed with the Chevrolet TBI??
Click to expand...


The chevy tbi uses a tach signal, so no crank sensor. :D


seamnew, it's possable your ecm has been disconected, a lot of people do away with it.
 
i don't believe the ECM has been bypassed, when i unplugged it i was curious and tried to start it, it turns over and over but does not start, plugged it back in and it started right up.

My friend gave me an idea, wanted to put it through here first, everything works, everything runs... now with all the loose connections and wires that arnt going anywhere, he mentioned just cutting them all out to clean it up a bit, what do you guys recommend?
 
thanks Dog

Now that’s interesting, I don't suppose there would be any problem running this on a tach signal from a MSD capacitor discharge ignition. A tach signal is a tach signal is a tach signal??
 
If the MSD tac signal wouldn't work - you could always buy their tac adapter - I'm sure either the stock one or the adapter would work.
 
CJ said:
If the MSD tac signal wouldn't work - you could always buy their tac adapter - I'm sure either the stock one or the adapter would work.
Click to expand...


you would need a filter to make it work right. Like you use with an aftermarket tach or rev. limiter
 
Last edited:
seanmnew said:
so what do you guys think about cutting the extra wires?
Click to expand...


Sorry for hijacking your thread for a couple of posts.


well this is JMO but I would rather disconect them from the fuse block than cut them, that way you could always put them back if you had to.

I had a lot of unused wires also, but I just bundled mine up and tied them out of the way. Just incase I ever need one of them. (some of them were hot)
 
some of them are hot currently, i intended to follow each one to the source and try and find out what they are (if anything) and if they are not for anything removing them... i do not plan to cut them at the main harness, but leave a few inches from the source if i need to reconnect anything to that source
 
I apologize for high jacking your thread too but Dog can you expound on the "filter" is this like a capacitor on the terminal? do you know of a place I can learn more about this it's new to me.:notworthy:
 
IOPort51 said:
I apologize for high jacking your thread too but Dog can you expound on the "filter" is this like a capacitor on the terminal? do you know of a place I can learn more about this it's new to me.:notworthy:
Click to expand...


I don't run a msd system, all I know is my howell tbi , rev. limiter and my tach all said "if you run a msd type system you need a filter".
I THINK it somehow takes the multi spark signals and reads it as only one so they know the true rpm's. But to be honest I never had to have one so I really don't know.
I'm pretty sure summit or jegs sells them.
 
CJ said:
If the MSD tac signal wouldn't work - you could always buy their tac adapter - I'm sure either the stock one or the adapter would work.
Click to expand...

Old Dog said:
you would need a filter to make it work right. Like you use with an aftermarket tach or rev. limiter
Click to expand...

IOPort51 said:
I apologize for high jacking your thread too but Dog can you expound on the "filter" is this like a capacitor on the terminal? do you know of a place I can learn more about this it's new to me.:notworthy:
Click to expand...

Old Dog said:
I don't run a msd system, all I know is my howell tbi , rev. limiter and my tach all said "if you run a msd type system you need a filter".
I THINK it somehow takes the multi spark signals and reads it as only one so they know the true rpm's. But to be honest I never had to have one so I really don't know.
I'm pretty sure summit or jegs sells them.
Click to expand...
Just run the recommended TAC adapter for the ignition system made my the manufacturer you are using (per my 1st post). They all sell them... You will have no problems as long as you use the correct adapter (MSD / MSD adapter - Crane / Crane adapter) and so on...
 
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