Cylinders 5&6 no bang bang?

So I swapped in a "JY" 4.0 with 135k into the wife's jeep. Hooked it all up, it fired right up but sounded like it had a miss. So I started pulling plug wires one at a time. Turns out that when 5&6 plug wires are pulled there is no change in the motor tone. Unlike 1/4. Compression in #5 is 125psi, #6 is 115psi. Wires and plugs both show spark. Noid light test on injector wires passed.Swapped injectors (twice) Tested resistance in all three sets of injectors. Checked all wires and splices New plugs, wires, cap, Roto,and distributor.

Jeep is a 91 aw4 np231j


HEP MEH PLEASE

Are you sure the compression numbers are right?

If they are too low it could do as you describe.

Other than that I'd make sure the wires for 5-6 are correct. Maybe swap the cyl 1 and cyl 6 wires to test the wires are good.

If the compression is correct. Other thing could be the valves are stuck closed.

Edit: maybe pick up in distributor.

Plug wires...I feel like an idiot.....some how.......I got 5&6 swapped.Now we just have a somewhat high idle. Wish I could post some pics it looks soo pretty all shiny and new ish.

Easy mistake we have all done it at least once.

I know what you mean about a job well done looking right.
I just redid just about everything that spins in the front of our 92 4.0, including the seals for the timing cover. What happened was We had a good name idler pulley break while on the highway shattered part of the bracket the idler bolted to and ac compressor sits on. Water pump tube got it too, damn near over heated. Put all new mopar parts in, including probably the last nos compressor bracket in North America, the front of that motor I'm actually proud of because it looks so good. Especially for a 300k motor, rest of the engine and engine bay not so much. Some day

Ok but those compression numbers can't be right. Stock spec is 150 with no more than 30psi variance between the cylinders.

I thought 120 was the bottom end of acceptable compression.

My 300k motor had similar numbers, I'm a little surprised a 100k motor wouldn't be more robust

Yes 120 is the bottom end, all other cylinders should be within 30psi of each other. Now you wouldnt want 180 in five of them and 120 in the last.