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Unread 12-28-2011, 09:12 PM   #1
tbramich
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Location: charlotte, nc
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engine swap now no spark.,,

back story- so i have an 89 yj with a 2.5l that i think had a cherokee engine swap before my time. the engine had a bad head gasket, low compression and knocking- but it did run and start everytime. i decided to swap it for a 94 yj 2.5l.

while both engines were side by side on the ground, intakes and exhaust manifolds were swapped. any electrical components (oil pressure switch and such) were swapped. also the distributor was swapped, but i decided to stay with the serpentine belt design so i used the 94 alternator.

i used the original wiring harness and spliced the alternator into the old harness, continuity checks out. i never removed the ignition module.

well everything is now connected and it cranks but i have no spark..

any ideas?

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Unread 12-28-2011, 09:46 PM   #2
moonshinefuel
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1995 YJ Wrangler 
 
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Is this a standard shift 5 speed? If so, which flywheel did you go with?
And there are two types of alternators, internally regulated, and externally regulated.
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Unread 12-29-2011, 04:33 PM   #3
tbramich
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i used the flywheel from the 94. actually i used the transmission and tcase from the 94 also. just swapped it all over as 1 unit
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Unread 12-29-2011, 04:42 PM   #4
Mark05059
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1989 YJ Wrangler 
 
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that would be your problem. You have a MPFI flywheel and a SPFI (TBI) carb. Either switch intakes back over or change flywheels. You will also need the computer from the 94
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Unread 12-29-2011, 11:44 PM   #5
SnowdogMarc
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1988 YJ Wrangler 
 
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I did almost the same swap into mine...88 TBI out and MPI from a 94 in.
Why didn't you drop the whole 94 in and upgrade to the MPI? Splicing in the computer from the 94 into your harness is not that hard and you can keep all your stock gauges as well. I think Mark is right and your going to have to swap parts back over and use the 94 computer. The 89 computer wont run the MPI setup.
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Unread 12-30-2011, 04:37 AM   #6
jsawduste
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2006 YJ Wrangler 
 
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Quote:
Originally Posted by Mark05059 View Post
that would be your problem. You will also need the computer from the 94
What Mark said.
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Unread 12-30-2011, 12:43 PM   #7
tbramich
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uh oh , dont have the pc. thought i could just swap the stuff over and it would work. ill see if the guy still has the pc, anyone have a link to how to splice it in?
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Unread 12-30-2011, 12:43 PM   #8
tbramich
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funny thing i did a v8 tbi swap in my last wrangler and had less issues lol
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Unread 12-30-2011, 11:22 PM   #9
SnowdogMarc
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Quote:
Originally Posted by tbramich View Post
uh oh , dont have the pc. thought i could just swap the stuff over and it would work. ill see if the guy still has the pc, anyone have a link to how to splice it in?
If you get the PC and the harness from the new motor...You can just cut the whole cable that goes to the 89 computer at the firewall ...(about 1/2" diameter about in the middle of the firewall) after you take the battery cables off. Remove the rest of the wiring from the old TBI motor labelling the wires from the sensors and anything that goes to the big block connector by the brake booster. I've got a list somewhere that has the wiring colors and what they should go to from my swap but will have to find it. ALL of your factory gauges will still work with the 94 but I think I had to swap over a couple of sensors from my 88 to the 94 for it to work. I mounted the PC by the brake booster and washer bottle securing it to the support rod.
You can also put the MPI harness on a diet by removing any wires not needed as well. Just follow them out and make sure they don't go to anything your going to need. I got rid of all the fuel pump wires and a few others as I kept the 88 harness wires that went to that.
It sounds very intimidating but don't be afraid of it. I went from this rats nest of wires...


To this...


I know this is from my Vortec swap but the MPI 2.5 is almost a stand alone install using the MPI harness. Only wires you really are using from the TBI are going to be the ground, Ign and power wires. Just about all the other wiring will be from the large block connector going to the starter and gauge hookups.
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l_______
/l ,[_____],
l---L -[]lllllll[]-

()_) ()_)--o-)_)____________VE6-SDG
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Unread 12-31-2011, 12:11 AM   #10
tbramich
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i got the computer today, plan to start swapping the intake and harness back over tomorrow and sunday
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