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will a 4cyl out of a 92 go into a an 86?

what's the difference between the two engines?

one has an AX5 the other is an AW4, what mating up issues will i run into?

 

one is out of a 92 YJ going into an 86 Commanche

The block is the same, so bolting it in is easy. The '86 uses a Renix-based throttle-body injection, while the 92 uses a Chrysler multi-port injection. That's a better system, but using it will require rewiring the entire engine compartment.

 

Which one has the AW-4? Can't be the '86, because Jeep didn't start using the AW-4 until '87, and I wasn't aware that they ever used the AW-4 in the Wrangler. Are you certain that's what the automatic is? Any way you look at it, the blocks are the same so any transmission off one will mate to the other with no adapters. You just have to be sure the flywheel is correct for the injection/ignition system you want to run, because the Renix flywheel and CPS will not work in the Chrysler system, and vice versa.

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I believe it is possible to run the Chrysler system as a stand-alone, and not have to get behind the dashboard. The Mopar Performance Catalog lists a conversion kit to change the old, carburetted 4.2L I-6 YJs to MPFI. The kit, as far as electrics and fuel, is basically the MPFI system from a '94 YJ, along with some extra parts to make it fit the older engine. The '92 MPFI 2.5L is just a 4-cylinder version of that same system. If you can run an old 4.2L as a stand-alone, I don't see any reason you can't do it with a 2.5L.

 

You would have to get a fuel pump from a 91 or 92 MJ, though. The MPFI system requires a significantly higher fuel pressure than the TBI. I don't know if the old fuel pump is capable of producing that much pressure with the regulator from the new system ... I sort of doubt it.

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i would prefer to run the TBI system on the engine so I don't have to put as much effort into the truck as the goal is only to get it running well to beat around in.

 

I don't really understand why everything from an 86 wouldn't swap over, but i need to confirm before i start buying countless jeeps to try and get everything going properly.

i would anticipate no major difference between the engines, so do you know if it would work or not eagle? (just taking everything off of the 86 and setting it up on the 94?)

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i would prefer to run the TBI system on the engine so I don't have to put as much effort into the truck as the goal is only to get it running well to beat around in.

 

I don't really understand why everything from an 86 wouldn't swap over, but i need to confirm before i start buying countless jeeps to try and get everything going properly.

i would anticipate no major difference between the engines, so do you know if it would work or not eagle? (just taking everything off of the 86 and setting it up on the 94?)

If you take EVERYTHING off the 'new engine, of course it'll work. The basic short block is the same. The problem is that I know going from Renix to HO on the 4.0L engine they redesigned the head and manifolds, so the old manifold ports won't line up with the new head. There are several work-arounds, the simplest being to use the Renix head on the HO block.

 

I don't know for certain, but I assume that the same applies to the 2.5L. You can tell easily enough -- yank the manifolds and see if the ports are the same shape and the same height relative to the top of the block. If you get lucky, it might be as simple as adapting the Renix throttle body to the newer intake manifold. After that it would be a piece of cake. You would, though, have to swap the old flywheel/flex plate onto the new engine, since the trigger tooth pattern is totally different. If you can't adapt the TBI throttle body to the new intake manifold, you then have to either adapt the old manifolds to the new engine, or swap the old head onto the new short block.

 

I have to wonder why you would want to run the Renix TBI if you have the stuff to convert. The MPFI setup runs a whole lot better and produces gobs more horsepower, which is a lot more benefot in the 2.5L than it is with the 4.0L, which had adequate power in the Renix version.

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i think the engine swap would be a lot easier and cheaper to do that way. i'm not looking to benefit from the swap, just to get the engine going. the engin is from a YJ as well, so i think the wiring issues would be even worse.

 

Any idea how the wiring would work just for curiosity sake?

I was mistaken, the jeep is a 94, so as for this stand alone unit, any idea where i can get info on it? any websites that can be read up on?

 

or do you have any knowledge of the subject? you seem to have a fairly good handle on it

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I am doing that swap as we speak. Mine is from a 91 YJ but all is the same IIRC. Mine had a stock AX-5 also and the YJ also had a AX-5 so theres no issue there. Here are some options.

 

1 This is what I'm doing I am changing over the wiring and all and keeping the MPI. Now there will be a few mismatched wires on the ignition side and the gages but as far as i can tell so far everything else should be simple. Also if you look to do a 4.0 swap you can imagine it taking the exact same amount of work unless unless its from the same year and style as your truck. It is going to be tedious with wires and all but it seems pretty simple through my planning so far. I should get into the actual swap this week and i should have the motor in memorial day weekend and hopefully running but we will see. I will keep my project thread updated if you want to whatch it.

 

#2 is to swap the block but keep your head and ignition. They are the same block but the head is MPI so it has to go. It would be very straight forward and simple and throwing a rebuild in it. I considered this but my head is also not in the best shape plus i had alot of other equipment on the motor that needed changed so it was actually cheaper for me to go for it all plus i get MPI!!!

 

Hope this helps you out. oh and BTW a heads up on pulling the Harness the junction block on the firewall where the engine wires run into the cab on the drivers side of the YJ should be seperated I.E. the drivers side of the bolck is YJ lighting and thats it so its not even needed so the only wires you have to swap in is the pasenger side of that junction block which actually seperates from the rest and then sperate your lights from the drivers side harness on the MJ and scrap the rest as far as i can tell. ON your MJ there may be a few extra doodads you may have to keep but so far I have just traced the lights portion. I can take some pics and post tomm.

 

Cole

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