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XJ Distrib Firing order Qs

J

jeepsrock

NAXJA Forum User
Location
LA California
I went and picked up th cap and rotor and noticed something very interesting when changing them. In both my chiltons and haynes manual it has the firing order as 153624. Additionally it has number one as the one next to the screw like...
origman.jpg


But i noticed my current setup is lke this kinda like it moved everything one up..Does this cause and adverse effect..Apparently its been running like this for a while. lol

current.jpg


Whats the deal...here.

pete
 
Nope, doesn't matter. The number 1 wire isn't always by the screw.
 
So are you saying it doesnt matter where number one is compaed to the screw aslong as they are in the right order ??? It doesnt make sense bc all pics nin all manulas have one next to the screw ??
 
Correct...your Jeep is running, isn't it? :D

What determines the position of the number 1 wire is where the rotor is pointing when the piston in the number 1 cylinder is at top dead center. So that can be at any position on the cap. That's why it is important to mark the position of the number one wire when you take all of the spark plug wires off.

What the manuals show is for illustration purposes only.
 
Well its running but at around 2000rpm she feels kinda strange and when in nuetral and you rev her she kinda makes a small bckafire/misfire type thing.

Pete
 
Yes it does matter where the terminal is relative to the screw. It can be made to work regardless by clocking the distributor, but if you went from one to the other w/out doing that, it will have effected the timing
 
Ok well which is it..... I am very confused between 1. the haynes/chiltons manuals 2. Some old caps oof mine has #1 written on them in diff locations 3. U guys.

Can a few please ppl take a look at their caps and maybe write their order in relation to the cap screws. I would really appreciate it as it would rule out this issue.

Or maybe someone diffenately knows the situation...

pete
 
Let me try to simplify this. If you change nothing else but the cap, and the #1 terminal is in a different spot, you will have changed the base timing. This can be compensated for by adjusting the position of the distributor as a whole. Is this something you just happened to notice or is there a performance problem that accompanied a change you made? If all is well, then don't worry about it.

Brian
 
Well recently i have started to have a vibe issue , that was partially cured by changing my motor mounts. The car feels a lot better after the repalcements but still the engine vibes a small bit while in nuetral when i rev it and in gear around 2200RPM. While trying to find a solution i started to change things one being the diff cap/rotor -Which while doing i noticed this was different that all my manuals comapred to what was curerntly in there, tho the last distributor cap i had in there was labled #1 and thats where spark wire one was, tho it doesnt match my books.

pete
 
Since the actual firing order is the same between the two caps you have, just the positions are changed, what I would do is put #1 cylinder at TDC on the compression stroke. Then, wherever the rotor is pointing, you know that that is where #1 wire goes and you can wire the rest of your cap accordingly. It's not too hard to find TDC, just pull #1 spark plug out and slowly turn the motor by hand until you can hear the air hissing out of the spark plug hole and stop when the piston is highest. Whatever you use to feel where the piston is at be carful that nothing breaks off in the cylinder or scratches the face of the piston, both of which I have heard of happening and both really suck to fix. Good luck.
 
First off, I wouldn't put to much stock in what the haynes or chilton manuals say or show. On my 97 TJ which has an OEM cap, the position is like the lower of your to diagrams, the screw is between 2 and 4 slightly closer to 4. The cam sensor lead coming out of the distributor is between 1 and 4, slightly closer to 1. Vibs at idle are common w/ bad engine mounts. Anything that hasn't changed after that could be normal or not, but I'm still unclear if you changed from one cap to another that was different or you're just referencing the drawings in a manual.
 
Well in short whenever i changed a cap before i just moved over the wires to the new cap in the same position.

It just happens that this time i looked at the haynes/ chiltons book while doing it. Right now i am driving it with the plugs like they have been (2nd Diagram) and just want to confirm this is the right way. I am hoping and really would appreciate if someone can confirm this if they take a look at theirs in a similar yr model (around 94).

Pete
 
I worked on Jeeps for @ 8yrs. All 4.0's had similar orientation to mine and your second diagram. The only difference through the years that I can think of was the distributor had indexing tabs on later years that prevent turning the dist. like you would normally do to adjust timing.
 
I just looked at my 95. Number one is approximately midway between the screws, looking like the second diagram. I think the first diagram is just wrong.

As far as I know, all 4.0's have a tab on the distributor to prevent turning for timing. Certainly the 87,89,93 and 95 all do. It's still possible to install the distributor wrong, and get it a tooth off, but you'll almost certainly have starting problems if you do, and I wouldn't worry about this unless you know it's been removed recently.
 
ok well that off the list....what can cause the jeep to kinda make a noise in the rear when in its in park when i rev it. It sound likes brub brub brub... Pete
 
Last edited:
Well i just took a look at the xhaust and hangers and they soom in good shape. This time tho when i turned on the jeep instead on idleing at 700-1000 like it normally does it idled at 1500 for a brief 10 sec and went down . Even tho it went down--once i pressed the gas pedal the engine vibrated around 1600-2200RPM , this would only be felt inside the car and really not outside. Other wise the jeep drives ok, but around that RPM it feels weird. I am guessing a sensor or timing issue but not sure where to start. i am not suer if its misfire or not.

thx
pete
 
You said you changed the engine mounts. How about the trans mount at the crossmember. The rubber can crack just like the frt. mounts, or sag, especially if its been soaked with oil. That is why I brought up the exhuast hitting the crossmember. There can also be metal to metal contact between pieces of the mount and brackets themselves. Another thing to check would be the harmonic damper on the frt. of the crankshaft.
 
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