4.0 head and EFI on a 4.2 block

Swaping 258 to 4.0, 4.0 parts to 258 etc!
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Jeep-Power
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Re: 4.0 head and EFI on a 4.2 block

Post by Jeep-Power »

if you were suspecting the crank position sensor, have you replaced the cam position sensor (it's in the distributor)

have you traced the voltage-- meaning have you made sure that voltage is getting to the PCM and PDC?

:huh:
vortec23
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Re: 4.0 head and EFI on a 4.2 block

Post by vortec23 »

now when i turn the key on I get fuel and coil for about 10 sec then stops but then I crank it and still nothing until i turn the key back to run then another 10 sec then shut off again
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Re: 4.0 head and EFI on a 4.2 block

Post by vortec23 »

Well things are still not good I need to know what relay or fuse does the DARK BLUE wires come out of.
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Re: 4.0 head and EFI on a 4.2 block

Post by Jeep-Power »

vortec23 wrote:Well things are still not good I need to know what relay or fuse does the DARK BLUE wires come out of.

Here's what I posted in the second page -- looks like the large dark blue wire comes out of the ASD relay:
Here's a shot of the '91-'95 underhood fuse/relay box (Power Distribution Center [PDC]) We gutted the thing and kept only two of the OEM relays. The two that are left are the ASD (relay "E" -- the one here on the left) and Fuel Pump (relay "B" -- the one here on the right) relays. Fuses that are kept: #2 fuse ( 30A - large green one -- upper left) & the #14 fuse ( 20A - protects the ASD circut - injectors & coil). EVERYTHING else is torn out and cut away (unless you use some for them for some auxilary circuts). The three wires that need to be hooked up are: the BIG (#4) red wire on the side of the PDC-- we downsized and lengthened it (with #12 wire). It runs right to the (+) side of the battery. The ground wires (the ones that bolt to the side of the engine block-- black with a brown stripe) get bolted back to the side of the block, and the solid dark blue wires get hooked to Ignition (+) power. Hook those three up and it is ready to run!
Image


here's a shot of the underside-- nightmarish in appearance, but all those cut wires have no power hooked up to them-- I left them long in case they are needed again.
Image


This is a shot of all the wires used btween the PDC and the rest of the OEM harness.
Image
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Re: 4.0 head and EFI on a 4.2 block

Post by vortec23 »

ITS ALIVE Got her running this afternoon... All good Thanks very much :cheers: :rockout:
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Re: 4.0 head and EFI on a 4.2 block

Post by Jeep-Power »

Woohoo! :cheers:

I'm not sure how much help we were, but it's always great to hear the good news!!
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Re: 4.0 head and EFI on a 4.2 block

Post by vortec23 »

Thanks, I'm having a couple issues but I will get it. I had to unplug the vacuum on the MAP sensor to get it to stay running.
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Re: 4.0 head and EFI on a 4.2 block

Post by Jeep-Power »

An update on this YJ-- Tom has sold it to my buddy Randy-- so it is still 'in the family'.

It is still running well-- we had to replace the cam position sensor (all-of-a-sudden it wouldn't start for Tom, as he was trying to sell it). randy tells me he is hoping to join me on the trail with it, as well as do a bit of snowplowing with it.
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Re: 4.0 head and EFI on a 4.2 block

Post by foxrider0127 »

Man whatta help this ste was nd to the guy who pos it, he answered every ? i had nd just got my 84 cj7 strated nd whatta difference the conversion makes!! GREAT POSTING!!!
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Re: 4.0 head and EFI on a 4.2 block

Post by Jeep-Power »

foxrider0127 wrote:Man whatta help this ste was nd to the guy who pos it, he answered every ? i had nd just got my 84 cj7 strated nd whatta difference the conversion makes!! GREAT POSTING!!!

Evan-- glad to help & especially happy to hear it is running! :cheers:
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Re: 4.0 head and EFI on a 4.2 block

Post by dhughes »

Just getting started on this. I've got a 1991 XJ that I'm taking apart for the swap. Where is the best place to look for what wires to keep and what to get rid of. Will the Haynes book have the wiring diagram? or is searching on line the best?
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Re: 4.0 head and EFI on a 4.2 block

Post by Jeep-Power »

dhughes wrote: Where is the best place to look for what wires to keep and what to get rid of. Will the Haynes book have the wiring diagram? or is searching on line the best?

The best place is a factory service manual (FSM).

the only thing I've found Haynes manuals to be any good for is starting fires.

Please let us know if you find one online. If not, I've been meaning to scan in all the needed pages out of my FSM.
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Re: 4.0 head and EFI on a 4.2 block

Post by fivestring »

Just joined this forum. First post...

Question.. Is there any advantage of buying the CPS on the harmonic balancer over just retrieving the donor vehicle flywheel/bellhousing to take care of the cps need?

I have already swapped to a newer style bellhousing to gain the exterior clutch slave on my '90YJ. I would think it would be worth pulling the transfer/tranny/clutch to swap flywheels and save $300. Besides that, my clutch throwout bearing is getting noisy, so I could change that out as well.

Am I missing something in my reasoning?



THE most excellent thread on this mod I have found yet, by far! Thanks so much for all the hard work and answers!!
Last edited by fivestring on August 29th, 2010, 9:42 am, edited 1 time in total.
I am dyslexic but I am also cross-eyed so I can read perfectly well.
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Re: 4.0 head and EFI on a 4.2 block

Post by Jeep-Power »

Thanks fivestring-

No advantage to the CPS, other than for the 4.2 folks, who don't have a late model OEM CPS setup.

The OEM CPS setup is more accurate (at least in theory) and definitely more reliable. I am on my third HESCO CPS harmonic balancer. The outer ring tends to drift/ shift off center (front to back).

I am in the middle of a build on y CJ, and switching over to the flywheel CPS is in the plan.

I say go for the flywheel CPS on yours!
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Re: 4.0 head and EFI on a 4.2 block

Post by fivestring »

Ok, thanks for clearing that up.

That has got to get expensive, buying those harmonic balancers, they ain't cheap!

And if you had those wiring schematics scanned in, I would be very happy to get my hands on them.
I am dyslexic but I am also cross-eyed so I can read perfectly well.
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