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Cylinders 2 & 3 not firing

A

alexgalexg

NAXJA Forum User
Location
Connecticut
I have determined on my 98 Xj that cylinders 2 & 3 are not firing. When I had it torn down to the head, all cylinders looked fine and all spark plugs looked the same. it has all new plugs, leads, dist cap, rotor ect. Lots of new parts since the teardown. It runs very rough and is hard to start. Once running I pulled the lead off each plug. no difference is made in the idle when I pull the leads off 2 & 3 but I can hear the lead popping indicating spark. What could be the problem here?
 
Make sure that any of the sensors you took out, went back into the correct place. Re-check to see if all of the sensors are plugged in. Did you number the fuel injector connectors before you removed them?


Tom
 
So it sounds like you pulled the head, correct? Did you notice any issues with the head gasket? Ideally you would have done a compression test before pulling the head.

Pretty much the only thing that would effect adjacent cylinders with only one point of failure would be a blown head gasket. A longshot would be arcing spark plug wires/Distributor cap.

Did this come on suddenly or slowly? How long has it been occurring?

Things that could cause this if the compression is fine are:
Collapsed lifters
Worn Cam Lobes
Bad injectors/wiring
Stuck valve(s)

These things are not likely since each would require multiple points of failure, not statistically probably
 
The story with this car is I bought it a week or so ago for scrap. Guy said the shop told him the head gasket blew. When I did the teardown I noticed aside from aging the gasket was fine. But I replaced it anyways along with alot of other components. After some fiddling with the throttle I got it to idle today. I thought it was cylinders 2 & 3 that arent firing but in fact after pulling electrical off injectors I found its 1-3. I just finished the rebuild last night and I didnt run the trick when I bought it because I thought the head was blown so I didnt want anymore coolant being eaten than needed. I did label and recheck all wiring and sensors. Also as a side note, it does burn clean (no smoke from exhaust).
 
Double check spark plug wires are on correctly and the injectors have the right wires as well.

Since you have it back together now, do a compression check.
 
Okay thanks, I do know the wires are on correctly. And I will do a compression check. Also do you know of a way to test the injectors themselves?
 
http://www.northamericanxjassociation.org/forum/showthread.php?t=1130831
http://www.northamericanxjassociation.org/forum/showthread.php?t=1130533
http://www.northamericanxjassociation.org/forum/showthread.php?t=1130509
Aside from a question about coolant and another about the ac compressor harness (which a figured out is different on many jeeps) This is the flood of threads. Since the day I bought it and wanted to get it home to now. Its all back together and Im just fighting with cylinders 1-3 and whatever is preventing them from firing. If any of you want pictures of the head before I slapped on the new gasket and put it together just pm me your name and ill send them via facebook after I run to the auto store to pick up a compression tester. thanks, to all of you for your help.
 
UPDATE: I know that cylinders 4 and up are working so I just did 1-4. Here are the compression readings (keeping in mind that this isnt a great battery).
Cylinder 1. 40psi
Cylinder 2. 28psi
Cylinder 3. 5 psi
Cylinder 4. 80 psi
 
None of those numbers are acceptable. I am surprised the engine even runs.

With numbers that low, I would be double checking that the tester is making a good seal when you screw it in. Does it have an o-ring?

Try again on all cylinders, with all the plugs out when you turn the engine over and do a wet test on each cylinder as well.

If those are accurate numbers, it is time for a new engine.
 
Last edited:
Wet compression test results:
Cylinder 1. 50psi
Cylinder 2. 38psi
Cylinder 3. 20psi
Cylinder 4. 83psi
Cylinder 5. 70psi
Cylinder 6. 150psi
Also while idling if I open the oil filler cap on the valve cover it releases white smoke. It does not come out of the exhaust or any other location, only the oil filler cap. Do you think that a new set of injectors and intake valves would revive the dead cylinders and restore my compression?
 
start looking for a new motor, you can get a good udes one for 100-300 around here
 
You either have shot cylinder walls and piston rings, or a very bad head probably with burned valves and bad valve seats, or maybe a warped head. You never answered my earlier question. Did you have the head tested, cleaned and reworked before installing it? That should always be done when replacing a head gasket.

Highest probability is worn piston rings and cylinders.

"I also have never done an engine swap."

There always is a first time.
 
alexgalexg said:
I thought about that but I dont have the tools to do so. I also have never done an engine swap.
Click to expand...

I did my first swap with an old craftsman 100 or so piece toolkit and a few specialty tools (all of which you can borrow from most auto stores) when I was a teenager. It's possible and putting a long block in your XJ would require the same skill (maybe even less) as putting the head and manifolds back on anyway so you've already proven you can probably do this.
 
alexgalexg said:
Wet compression test results:
Cylinder 1. 50psi
Cylinder 2. 38psi
Cylinder 3. 20psi
Cylinder 4. 83psi
Cylinder 5. 70psi
Cylinder 6. 150psi
Do you think that a new set of injectors and intake valves would revive the dead cylinders and restore my compression?
Click to expand...

The answer is NO. If you really have the compression gauge sealed correctly and not leaking around the spark plug hole, then you have a junk engine. You only have one of the six cylinders that is good. You have numbers that are lower than I have seen in decades. With those numbers, I am surprised the engine even runs.

Not all compression gauges will work with a 4.0L. The connection has to be able to reach down through the head to get to the threads. It also should have an O-ring to seal when screwed all the way down.
 
Since it read 150 psi on one of the cylinders that is working, the tester is likely working, thus the engine is shot. Can't the engine be rebuilt or stroked? Obviously a used JY engine would be the cheapest rout.
 
If the cylinders aren't worn too much, you can definitely rebuild it...or stroke it, but that can run some serious bucks. I figure a rebuild will run probably $2500+ and add another $300 to make it a stroker. You can snag a used engine in fair shape for less than $400 in most markets.
 
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