93 2.5 YJ No spark issues

[xjdrew]

So I got a 93 YJ that I bought not to long ago. It needed a new trans and the motor had a miss to it. The wire harness was pretty tore up on it also but it would start every time.

I got a good deal on a motor and tranny out of a 95 YJ with wire harness and computer (heard running also)...
So I swapped everything over including the new harness and cpu. I really didn't have to do much with the wire harness because everything was still connected on the motor all I had to do is connect it to the body harness, for the exception of the speedo and fuel pump wires that I had to rewire.

So I got to crank it and it will turn over but will not start. I got fuel pressure, I hear the fuel pump coming on. I just got no spark. Here is what I've checked so far and replaced

1. I got power at the plug of the ignition coil
2. I replaced the ignition coil
3. Checked and replaced the crankshaft sensor (had power at the plug)
4. Swapped cpu's and put the one for the 95 back on
5. Swapped distributor (new cap and rotor)
6. Checked all the ground wires
7. Checked for codes and none are present
8. Checked all the fuse's and all are good

Sorry for the long post but I'm about to go crazy with this thing .. Any ideas?

 

[gt500swim]

did you check the cam sensor located under the cap? could be the ingnition control module... also check ALL grounds. and check all connections. zj's have a nact of getting a bad connection from the coil to the computer causing a no spark condition.

 

[gt500swim]

is it a automatic or manual tranny. also a common problem notorious in xjs is the neutral safety switch located on the tranny. causes a no start condition. could be another option to check out

 

[gt500swim]

are you getting a full 12 V to the ingnition coil? is the coil grounded to the block good enough

 

[xjdrew]

When I replaced the distributor everything was new, I'm pretty sure I don't have a icm on a 93, it is a manual tranny so no nss, and I'm getting full power to ignition coil. As far as the ground wires that's what I leaning toward but I've checked and checked them again and all are good to go. Thanks for the info...

 

[Jody Treadway]

Here's where to start: the crank position sensor generates an AC voltage when cranking. Measure that voltage. IIRC it should be approx 1.0 volt AC.
Also, to see if the coil is good or not here's what ya do. Place a paper clip between the 2 pins of the coil connector (unplug the coil first) and hook a test light up to the positive side of the battery. Now hook up the other end of the light to that paper clip you installed earlier and have someone crank the engine. If the test light flashed, the crank sensor is doing it's job. If it's not flashing then the PCM is not seeing the crank reference signal for whatever reason (usually crank sensor).
Really, really check those grounds at the dipstick tube stud and also on the side of the block. Loose, dirty, or missing grounds can create headaches.

 

[xjdrew]

I went out this morning to do the paper clip test on the ignition coil. It did flash when trying to crank, I proceed to check the crank sensor and it generated 1.7 volt ac when trying to crank. I was thinking the pcm, but both be bad? Is the pcm plug and play? I took some pics of the ground wires and such maybe y'all can see something I'm missing.. Thanks by the way for all the advice

 

[Jody Treadway]

If you have power at the coil and also if the coil is being grounded and ungrounded, but still no spark, the coil may be bad out of the box.

Coil wire good going to dizzy? Sure it doesn't somehow have a 4.0 distributor installed? Saw that one time, took me forever to figure that one out.

 

[gt500swim]

if your getting signal to the coil but no fire from the coil then then id change out the coil again, cant hurt.

 

[xjdrew]

So this where I'm at, I changed out the coil again and still nothing. Changed out the wire from the coil to the cap, also nothing. I pulled the distributor to make sure it was the right one and that was good to go . At this point I'm pretty sure its going to be something so simple I'm going to be kicking myself about it.. Maybe its in the harness??

 

[gt500swim]

you say your getting to the coil but the coil isnt energizing.... try splicing out a new connecter to the coil(or a different one)

 

[Ray VanBuren]

Had this problem recently on my '91. Turned out to be the auto shut-off relay in the Power Distribution Center.

 

[xjdrew]

I finally had some time today to mess with it a bit. I replaced the connectors like suggested, the one from the coil, the distributor, and crank sensor and nothing. I checked all the relays at the Power Distribution Center and all good there. What I did notice was that the PCM that I thought was from a 95 is actually from a 91, so I put the original PCM back on and also nothing.....

 

[gt500swim]

damn son. are you sure the pcms you have are for the 2.5 and not for the 4.0... check the way the coil is mounted to the motor. are there any ground wires around there

 

[xjdrew]

She is alive!! It ended up being the connector that goes to the body harness, the year change was the main factor. It had a couple of wires in different spots in the connector, so I just swapped the pins out ans I was good to go

 

[gt500swim]

nice job dude