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View Full Version : Hard to track down CEL - Cyl 2 Misfire


LessThanJoe
October 18th, 2017, 19:51
I've been trying to get rid of this check engine light for almost a year now. Inspection will be due in Feb, and I'm really getting tired of this light on as well.

98 XJ 4.0/AW4 - 370k mile DD mostly stock, rebuilt at 250k.

Cyl 2 Misfire code came on almost a year ago while driving on the interstate. No issues that I could tell, engine ran fine, I cleared the code but it came back. And it hasn't left. Sometimes it goes away on its own, but comes back a day or two later. I have left the battery disconnected overnight several times just to check. I've checked the fuel pressure over and over, I've checked the compression twice. There is no oil leak and no coolant leak.

I have replaced:
Spark Plugs
Spark Plug Wires
Distributor Cap/Rotor
Crankshaft Position Sensor
Throttle Position Sensor
Distributor
Camshaft Position Sensor
Fuel Injectors
MAP Sensor
Valve Springs

After I changed the valve springs and reconnected the battery, I went 1000 miles thinking I had finally fixed it. Well, today it came back.

I never feel any rough idling or running, never any loss in power, nor a loss (or gain) in MPG. If that light didn't come on I'd never suspect a thing.

Anyone have any other thoughts or suggestions I havn't tried?

JohnX
October 18th, 2017, 20:26
Out of curiousity, what were your compression numbers? First and last for all cylinders?

Have you run a leak down test?

Have you tried switching position of injectors, plugs, wires, etc. to see if the problem moves?

Have you checked torque converter bolts...loose blots can cause erroneous CPS readings.

Were the plugs and wires replaced at EXACTLY the same time? Could be carbon track if done on different days.

clydefrog
October 18th, 2017, 21:08
Out of curiousity, what were your compression numbers? First and last for all cylinders?

Have you run a leak down test?

Have you tried switching position of injectors, plugs, wires, etc. to see if the problem moves?


This.

LessThanJoe
October 19th, 2017, 12:31
Out of curiousity, what were your compression numbers? First and last for all cylinders?

Have you run a leak down test?

Have you tried switching position of injectors, plugs, wires, etc. to see if the problem moves?

Have you checked torque converter bolts...loose blots can cause erroneous CPS readings.

Were the plugs and wires replaced at EXACTLY the same time? Could be carbon track if done on different days.

Last time I checked compression was a while back, at the beginning of this. I don't remember the numbers but I do remember they were withing 10 psi of each other and all in high range. I'll try to get out there today and give it another check.

Leak down test was not performed as compression tested good and even in all cylinders, so I didnt go that far.

Plugs were swapped on day 1 of CEL, did not help. Wires were swapped between cyl 2 and 4, and did not change anything. At that point I changed all the spark plugs and wires to be sure, as well as cap/rotor, all on the same day.

Converter bolts were checked, all torqued correctly and plate was inspected and found no obvious cracking that I could see.