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Discussion Starter #1
I just had my transmission rebuilt and got it home and the check engine light comes on!:mad:

I checked the code and it showed 43 "Multiple cylinder misfire".
I just replaced plugs, wires, ect. a couple months ago. It has been idling rough (lopes), but a mis-fire? Anyone have ideas?
 

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If it's been idling rough I'd say that your plugs aren't gaped right.
 

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sea foam it.
sea foam will clean out the motor. stuff works fantastic

1/2 a can down the throttle body while the motor is idleing. you have to pour slow or the motor will turn off. after a half can is poured shut off the motro for 10 minutes. fire it up and watch is smooooooke. once the smoke clears (can take up to 20 minutes) the motor will run smooooth. pour the other 1/2 in your gas tank. Sea foam will eat up the caron deposits and clean out your injection system. if it doesnt help then you wasted 5 dollars on a can of whoop ass, and you still cleaned out the carbon in the motor
 

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Being from close to the same climate as you. I would say some water (snow) in the gas. My 98 went throught the same problem code before I traded it in. Added a couple bottles of the red ISO heet and cleared the code. After a couple days the problem went away.
 

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That sounds way too good to be true Rawkon. Any one can confirm it :)

Misfire is one of the biggest causes of rough idling. I would say whowever changed your sparkplugs didnt push the wires in or something of that sort. Thats why you are getting misfires.

I dont know how experienced you are but a misfire is when a cylinder does not fire in its power stroke. I'm guessing multiple misfire means more than 1 misfire in a cylinder and not multiple misfire in more than one cylinder.

I'm just wondering has it been idling rough ever since you got ur sparks changed or is it just whanever?
 

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Discussion Starter #6
It was idling rough before I put new plugs and wires in. I already tried sea foam. I'm really at a loss.
 

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Did you try dry gas? When you change plugs and wires did you also change the distributor cap and rotor button and make sure the gap in the plugs was set correct? Did you try checking it at night or in the dark with your hood up to see if there is any arching along your wires while its running(make sure headlights are off)?
I would check these ideas out first since they would be cheapest to fix.
 

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The 43 code is a fairly well known but not easily cured problem. I've had up to three '43' codes stored in my computer at once... as in 12 43 43 43 55. It's not cured by replacing ignition wires, spark plugs, using Sea Foam, fuel injectors, or anything else that simple. It's most commonly caused by the valves, initially from a bad batch of weak valve springs in '97 and early '98 engines. Then that later causes the valves to not seat properly so a valve job is needed if the springs weren't replaced soon enough.

I replaced my springs last year but that was after 7-8 years of intermittent 43 codes so my 4.0L now needs a valve job. As a matter of fact, I hadn't had a 43 code in probably 6-7 months which was about the longest it had ever gone without one... but wouldn't ya know it, it came back yesterday morning. :mad:
 

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If its the valve springs i would gues it will be making pufking noises since the compression would go to waste in the intake or the exhaust manifold?
 

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Discussion Starter #10 (Edited)
did you also change the distributor cap and rotor button and make sure the gap in the plugs was set correct?
yes I did. I did not check for arching though.

If i bought a code scanner, could I narrow the code down to the exact cylinder? Since the 43 code is generic for all four?

And how difficult is it to change the valve springs, i have a Haynes manual, and i am mechanically inclined to some point.
 

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You gotta open the valve cover. I dont know exactly how the jeep head is designed but on many cars you can get away with just removing the valve cover and just compressing the springs with a spring compressor and just removing the pin at the top of the valve and then replacing the springs with a new one with everything still in tact. The worst it can get is you will have to remove the head and unbolt the camshafts which will then require you to set the timing and also will reqire you to remove or disconnect the intake and exhaust manifold.
 

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try sea foam, 5 bucks and it may do the trick. it wont hurt anything. id try that before doing a valve spring job. I had a multiple random misifre in my 97 5.9 ram and sea foamed cured it. i had 2 mechanics looks at it with scopes and all kinds of stuff, pouring the remaing half in your gas tank will help too
 

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Sea Foam will not help this problem in the least but at only $5, I guess it's worth a shot.
 

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jerry did or do you hear any valve chatter or ticks???

i didnt think the 2.5s had the same issues as the 4.0s on the valve springs. to me i would do all the cheap little things first before doin a valve job or valve spring replacement.
Thanks for the info JB
could be something as easy as a coil
 

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jerry did or do you hear any valve chatter or ticks???

i didnt think the 2.5s had the same issues as the 4.0s on the valve springs. to me i would do all the cheap little things first before doin a valve job or valve spring replacement.
Thanks for the info JB
could be something as easy as a coil
Never any valve noise, ticks, etc. on mine. Installing a new high-output ignition coil didn't help mine either, I replaced just about everything on my TJ before Jeep finally came out with the TSB describing the '43' code issue and how to cure it. Before the TSB came out, one of Jeep's senior-most engineers (the same guy who developed the concept for the Rubicon) contacted me about my 43 codes, curious about the problem. He ended up sending me a giant "care package" of stuff to try. It contained a new set of fuel injectors, fuel injector wiring harness, clockspring, ECM, etc. that I tried one at a time. That was after I had replaced everything ignition related and cleaned all the electrical connectors. Obviously it was nothing easily replaced. A few months later is when the TSB about the valve springs was released. But if the problem has gone on very long, it likely needs a valve job in addition to the valve springs, as mine now needs. Replacing my springs eliminated 90% of the 43 codes, but they still come back. My Jeep has a 43 code right now but I haven't driven it much since it developed Monday morning after returning from Sledgehammer. :)
 

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nice thanks for the info jerry

you can do a valve spring test to see if they are in spec before replacing them. but since they are out new valve springs dont cost that much and you may as well replace them if thats the case.
 
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