I recently put a 92 4.0 HO into my 90 XJ. It has started 3 times since I replaced the engine. The jeep has never started every time since I bought the thing. To start it i would have to leave the batter cables off for awhile and then connect the negative cable first and then the positive cable. If i did it in a different way it would never start.

After I have started the engine the 3 times it has not started since. I have replaced the crank position sensor twice and have replaced the coil.

I am at a loss of what to check next. I also found out the 88 schematic I have been using for my 90 does not match up for the wires on the connector going into the ECU. Does anybody have an electrical schematic as well for a 90 XJ 4.0?

Thanks in advance for the help.

 

is there any way to check if fuel is getting to the engine?

 

theres alot to that swap... hope you did it all! i kept the 89 harness in mine... besides the TPS everything else fit right up electrically wise anyway...

 

What did you use from the 92,complete engine or the longblock?

 

It has fuel pressure on the rail.

I bought an entire engine with accessories from the JY. I tore it down and replaced rear main seals, head gasket, pan gasket, oil pump, and checked the head.

I was able to use most of the components that came with the engine. I reused my old exhaust manifold though so I didn't have to do exaust work. I also had to buy some fuel line addapters.

 

u may be alright... used the newer throttle body? i found my factory 89 harness MAP sensor plugged right into my 94 throttlebody... all i had to do was wire in the right plug for the TPS... which still aint right... lol

 

I put a 91 in my 89,I had to use everything from my 89,I tried to use the flexplate from the 91 without knowing it was different and ended up taking the motor back out to put the flexplate from my 89 on,they are different,mine would not even fire up. Mine runs fine now. I know some have spliced wires to use the newer connectors but the pcm is still different and runs things different. I think anytime you do a swap you should use the sensors,harness,pcm that are compatible.

 

I used my 90 electrical harness and the 90 flex plate when I put it back together. I noticed the cut outs for the crank position sensor where in a different order and spacing on the 92. I used the intake and fuel rail from the 92 as the intake from the 90 did not fit. The fuel rail did not fit as well from the 90. I went through the schematic for an 88 and the main thing I see that would stop it from initially getting spark is the Crank sensor. I have tried jumpering the sensor straight to the ECU to see if that would help. My schematic for the 88 does not have the same ECM pin out as the 90 though.

I am just looking for anything to check.

PS: I also opened the cover on the ECU to see if anything was smoked and it is a very clean board.

 

http://www.lunghd.com/Downloads_and_...ion_manual.pdf

Found a trouble shooting manual and a wiring diagram.

 

Perty sure it is the ECM found all my wiring was correct (thought it was but wanted to double check). I have all the input signals going into the ECU but no power on the yellow ignition wire. Going to the JY to get an ECU.

 

u used the 89 intake? told by lots of folks on here that the ports dont line up... thats how mine was when i got it... everything bolts together but the ports dont line up well on the head... thats why i just swapped everything over... the pcm doesnt really run things different... mine runs fine now with the ther MAP sensor plud wired in... it takes the same reading no matter what sensor it is... why waste time and money swapping the harness and comp when all it took was 3 spliced wires... My MAP sensor plugged right in even...

 

i was gonna say... cause when folks are swapping the new 6 speed in these cherokee the crank sensor is in a different spot and they just cut the plug and spliced in the plug and it all worked fine... so shouldnt be that hard... there is all this expensive stuff to buy to remount the sensor and junk but this guy just spliced in the new wire pluto fit the 6 speed sensor and it worked fine... like my TPS... so it should be to hard to figure out! goodluck!

 

'90 is Renix, '92 is Chrysler. I'm pretty sure you're gonna need a Chrysler ECU.

 

im saying right now... right as i sit right dang here... my jeep runs great... come and drive it... renix harness and ecm... HO TPS... works great... going to do a write up so people dont waste there money on the HO conversion TPS adapter from hesco... Im all about trying new things... if everyone did then these XJ's would be unstoppable...