Need some help, I pulled the 2.5 out of my 87 charakee and replaced it with a 2.5 from a 97 wrangler. I put the flywheel,throtle body and h. balancer from the 87 on the 93.I've got spark and fuel but it wont run.I pulled each plug and with the valve cover off they look like there all fireing on compresion. I even squirted starting fluid in the intake, no fire.Any imput would be great. thanks

 

Here are some things to check...

Is it firing on #1 at the right time? We take a timeing light, mark on the fan pully when it should fire, and turn it over and see when it is actually fireing.

Are all the wires comming from the plug connected? Book says grn/wht goes to tach and to Diagnostic connector. Yellow goes to Oxygen Sensor and Diagnostic connector, Orange/Black goes to Electronic Control Unit and other Diagnostic Connector.

If none of this works, I have a VW aircooled moter we can try to put in.

Scott

 

I'm looking to make the same swap, different years (1986 up to a 1992). My question relates to the use of the TBI vs the MPFI from one to the next. I'd like to keep the MPFI on the newer engine (more power, possible gas mileage increase). Can this be done without swapping the ENTIRE wiring harness from the 1992? I have the injectors and engine harness and computer available. Anyone tried this switch? Thanx for any help.

 

You do need the computer and harness to make it fire. They have different parameters in the computer and several different plugs too IIRC.

 

By different plugs, I'm guessing you are referring to different plugs on the wiring harness. I.E. the TBI harness and the MPFI harness are different, so I wouldn't be able to plug the MPFI into the existing vehicle harness. Is this an accurate statement? How about computers? Would the '92 computer plug into the '86 harness? Is there a pin-out diagram of each harness available? Can the TBI plug be made to work with the MPFI harness?

Next question, then, is - will the manifolds from the '86 swap to the '92? any other electrical bugs to work out?

Final question. Would it be less expensive to rebuild the '86 than try to swap? Thanx

 

Anything can be made to work in anything if you have enough money to throw at it.
Yes I was refring to the wiring harness plugs and the head may have to go eith the intake and exhaust.
I personally would rebuild what you have instead of changing unless I just changed the short block and retained the Original head and dizzy.

 

CJ77, is that what you did? You used the block (like a long block swap) from the '97 but retained all the other parts from the original vehicle?

 

I just did a stait swap. It turns out after talking to the yard I bought the motor from that I got a motor from a 90 not a 93. The book that they have says 86 to 90 2.5 are compatable.Still have not been able to get it to start. We did a compression test and all four were at 60, I'm told it has to be at least 90 to fire so I've been squirting lube into the cyllinders to loosen up the rings.If that dos'nt work my next step will be to take it to a wrench to find out if its a bad motor.

 

when swapping the flywheel, did you install the flywheel with the proper crankshaft position sensor placement? the chilton manual mentions placement for the 4.0l 6cyl, but not the 2.5L (figures, huh).

 

also, did you swap the ignition systems? it seems '84-'88 is HEI, and '89-?? is different, in that it uses the CPS, whereas the HEI system is totally self contained. just another thought.