Hello everyone,

I'm getting ready to do my engine swap this weekend and am trying to fix a problem in the process. The current setup I have now: Mopar MPI, Jacobs ultra coil, and jacobs miliage master. My jeep will not shut off when I turn the key off. The ignition switch is brand new so I have ruled that out. But is this the sign of a bad coil. I don't really know how the whole shutdown thing works but I always thought that after the key was shut off the coil grounded out and stopped sending spark signal to the distributor....but how does the coil get its signal on a fuel injected? Anyway I would like to fix it while I have everything out and its easy to see all of the wiring....and I'm tired of killing it in gear.
<img src="/forums/images/graemlins/shiner.gif" alt="" />
This motor swap is going to be pretty sweet. 4.2 block bored 30 over, 4.0 head, borla header, york onboard air and fuel injection. wooohooo. <img src="/forums/images/graemlins/smile.gif" alt="" /> Now if I could just fix the body <img src="/forums/images/graemlins/shiner.gif" alt="" />

Thanks for the help

when you turn the key off alot of stuff should stop getting power. the computer should go from an ative mode to a standby mode, the injectors should go open, and the coil should stop recieving voltage from the coil. it is not like an old carbed car where if you were to leave power at the coil it would just keep on running. i bet it is your switch, there is alot of things that need to stay on. does your bat go down if you leave it parked for a long period of time?

it sounds like the system was wired wrong, the feed wire
on the switch should kill power on the fuse block when
shut off, someone has put a constant hot feed to the block
bypassing the switch ,the only thing your switch is doing
it sounds like is sending the hot feed to your solenoid
to activate the starter . cut everything off on the
vehicle an take neg cable loose from battery if it is
arcing a little there is a closed circuit somewere.
the switch could be faulty ,i dont know what type of
steering column you have but if it is the rod type
that is exercised buy the switch, check an see if
actuator is going into full stroke to line up contacts.

Yeah I've been working on this one for awhile. When I first bought the rig it worked fine...and every once in a great while it will turn itself off...but not very often. The switch is actuated by a rod on a tilt steering wheel. And when the key is turned off everything but the engine turns off. (Everything as in in-cab stuff) I have tried leaving the ignition switch free and moving it by hand with a small screwdriver and still the same thing happens.

So what your saying is that the Computer is still getting power? Could it be that the alternator is not properly grounded thus sending power to everything and keeping it "ALIVE" ahahahaha....yeah <img src="/forums/images/graemlins/shiner.gif" alt="" />

Thanks for the help guys I am still pondering.

there may be a bad diode or somthing in the alternator, if i remember correctly some older cars had a problem with the regulators creating enough voltage to keep feeding everythig else enough power to keep it running. the solution was to pull the alternator b+ wire off and the car would shut off. you could try pulling the b+ wire off yours and see if it keeps running, but there should be switch to tell the computer when to run and when not to.. i think that swith is malfunctioning or possibly shorted. do you have the wiring diagram to the system you are rusing now?

I went through the entire 82' portion of the engine bay wiring and took out everthing that didn't belong and I fixed the problem and created a much bigger one <img src="/forums/images/graemlins/frown.gif" alt="" />. I finished the engine swap this weekend and fired it up last night. Apparently the the Crank Position Sensor and the Oxygen Sensor were too close to my new header and they caught fire about a mile down the road. I tried splicing the wires together and relocating them about 10 inches away from the header. I think when it caught fire and everything arked out and shorted out the computer or something because now I get no spark but the coil reads 12.5 volts at the post with the key just on. In my trusty chilton manual (pronounced POS) it says that the Computer needs to be replaced...Everything else seems to work right as far as the Fuel pump relay and making all the proper clicks. I'm going to have to look at the wiring diagram for the EFI kit to see where I need to put a light bulb in so that I can read the codes off the computer. I'm hoping just the CPS is fried. Do I have to use any jumper wires on the diagnostic connector to pull the fault codes up? if so where to I plug them in at? Thanks

The good news is the engine runs like a dream...real deep base exhuast and a smoooooth runner.
anyhow I cant even see straight right now I am so dang tired. I have been up 3 days from 7 am till 3 am the next day till today at noon I finally quite and parked it. <img src="/forums/images/graemlins/frown.gif" alt="" />

oh yeah and my wife of course chimes in and says I need to find a new hobby <img src="/forums/images/graemlins/angry.gif" alt="" />

if its like an early obd1 wrangler.. just flip the key on and off 3 times...

if you are unlucky you burnt out the computer, if you are lucky the CPS is toasty.

Do you think if I unhooked the computer and the CPS the dealer would be able to test them?

Thanks for the help sunder

maybe not the computer, but if you can get it to them they can certianly check the CPS with a DSO. you'd need to get the whole jeep to them with all the stuff in it. as far as i know they don't have a magic box they plug the CPS or computer into. they'd either back probe or pinch through The CPS and crank the car with a DSO hooked up and see if they get signal. they'd also just hook up a scan tool to the computer and check its functionality with a handshake and cranking it. if the computer won't handshake then it is of course dead... but if you are getting voltage to the coil its semi working.

i'd hook the MIL light up and try and get some codes before taking it to a shop.

Well Sunder I got lucky...real lucky. Just the CPS was fried. I installed a new one tonight and drove the beast home. One more question about the mopar MPI...Do you know what I need to set the timing at initially. I know that it is controlled by the PCM but is there a setting at first to make sure it is right?

Thanks for all your help

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