I thought I had this problem fixed but my recurring problem of a rough-running engine and three (3!) '43' codes are showing up on my '97 TJ 4.0L again! <IMG SRC="smilies/confused.gif" border="0"> The 43 code decodes out to a dwell or two other problem (listed below) which are not much of a clue since I'm getting three of them in a row (12, 43, 43, 43, 55)

What I've done so far... replaced the ignition coil, plug wires, rotor, distributor cap, plugs, and I have thoroughly cleaned (several times) every single electrical connection going to every single sensor and the computer connections too. I've run umpteen cans of fuel injection cleaner since in the beginning, I thought I might have a clogged fuel injector.

This problem doesn't come on gradually, it's like something electrical just starts the engine idling roughly... like it's running on 5 cylinders. Then a minute or two later the Check Engine light will come on. Disconnecting the battery and cleaning the connectors usually cures it for a few weeks but then it comes back. This problem has been plaguing me for about the past year. I thought I fixed it several months ago when I got very aggressive with everything like the sensor connectors and computer connectors but dang, the problem came back today! The plugs are not fouling, they look perfect.

Besides what the guides say on the '43' code, can anyone tell me what that code is really saying??? The guides say this:

43 Peak primary coil current not achieved with max dwell time (huh?)
OR
43 Cylinder misfire (why I cleaned the injectors)
OR
43 Problem in power module to logic module interface (why I spent time cleaning every connector I could find).

If you can tell me you've had the dreaded '43' codes before and have cured it, I'll owe ya!! Arrrggghhh!!
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[ 09-25-2001: Message edited by: Jerry Bransford ]

The coda 43 means that one of the cylinders is not firing. You could have and injector that is bad, bad spark plugs(autolites are extremely bad),bad crank position sensor,or a loose connector to one of the injectors. The first thing you need to do is determine which cylinder or cylinders is/are misfiring. Once you determine which cylinder is misfiring check to be sure you have spark from the wire.If you have good spark from the wire swap the plug with either a new one of from another cylinder.If the misfire goes away(new plug) or changers cylinders (used plug from another cylinder) then you have found your problem. If their is no spark or intermittant spark their is a stud behind the oil filter and above the starter that has three wires attached to it. make sure they are tight. To see if the injectors are working hold your hand on each one with the engine running, you will be able to feel the injector vibrate when it squirts. If one does not seem to vibrate then stick a light( dash or side marker type light with the prongs straightened out) into it to see if it is recieving a signal to open. If no signal check the wireing if it is getting a signal then replace it.

Good ideas, thanks. What is a good way to tell which particular cylinder(s) is misfiring? Heck, I might even rig up a stethoscope to listen to the injectors too. That might help a lot.

I have several or the little coil spring things that are used to connect plug wire to the plug with the cheaper timing lights. I hook them up then using a long screwdriver I short to ground to kill spark to that particular cylinder,however if you have AC this will not work for the #1 cylinder since the compressor is in the way. you can just pull the plug wires and put them back on it is just a little slower and you have to make sure they are loose so you dont pull the end off.

use a voltmeter to check and make sure you are getting power to your injectors. They have been messed up on my 94 4.0 b4 <IMG SRC="smilies/emb.gif" border="0"> <IMG SRC="smilies/crybaby2.gif" border="0"> <IMG SRC="smilies/jeep2.gif" border="0"> <IMG SRC="smilies/jester.gif" border="0"> <IMG SRC="smilies/laughing.gif" border="0"> <IMG SRC="smilies/maggie.gif" border="0"> <IMG SRC="smilies/massey.gif" border="0">