99 xj cylinder 3 & 5 dead

[skinny skull]

having trouble with my 99. 4.0.
good compression across the board 130+
injectors are firing.
good spark

Ive swapped plugs and wires and moved injectors around and the miss stays on those two cylinders. distributor has some play in it but im getting spark. i find it odd that the two dead cylinders are next to each other on the distributor but im getting spark at the end of the plug wires.

any suggestions

 

[lawsoncl]

Are you getting injector pulses? On a 99, they all get +12-volts via the AD relay, and the computer controls the grounds. So you should see constant 12-volts on one side of the injectors, and the other side dropping to ground as it pulses. Or something at least bouncing around if measuring with a basic meter or a noid light.

 

[skinny skull]

Yes I am getting trigger to injectors

 

[lawsoncl]

Wires in the correct spot on the distributor? Just checking since some of the diagrams out there (looking at you Haynes) are wrong.

 

[Runnin'OnEmpty]

........Ive swapped plugs and wires and moved injectors around and the miss stays on those two cylinders. distributor has some play in it but im getting spark. i find it odd that the two dead cylinders are next to each other on the distributor but im getting spark at the end of the plug wires.

any suggestions

Check the inside of the distributor cap for carbon tracking,
specifically near the 5-3 terminals. Replace the cap if
tracking is suspected...

 

[8Mud]

Check the inside of the distributor cap for carbon tracking,
specifically near the 5-3 terminals. Replace the cap if
tracking is suspected...

I'm thinking the same thing, he is getting crossfire, spark jumping to the wrong wire. He might want to ohm test his cables. Really high resistance cables can cause all sorts of grief.
I check spark by opening an old plug to 60 thousandths, holding it on a good ground, and looking at the spark.
Another possibility is the distributor shaft, not beyond the realm of possibility he has a variable rotor to cap gap.

 

[CarlosFromPhoenix]

How do post/start a thread on here? I just registered and I needed some help/guidance with my XJ.

 

[8Mud]

Go to the "OEM Tech Discussion" page, upper left-hand corner blue button "New Thread".

 

[skinny skull]

Thanks for the help. So far nothing has fixed it. I have swapped from a known good running xj: complete distributor, new cap button and plugs and wires. O2 sensor, pcm, complete injectors and fuel rail, throttle body. Checked all grounds. Noid light all injectors. Spark tested all plugs and wires. I’m stumped. Only thing I thought to throw at it is a new crank sensor. Again you unplug either #3 or #5 injector and nothing changes

 

[four_shot]

Do.a "running compression check". Some times valve issues don't present at the cranking speeds that standard compression test occur at.

Rule of thumb, running compression should be about half of "static" compression.