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Discussion Starter · #1 ·
I have a 97 TJ with only 100k miles on it. I purchased it in September of 2014 and for the last few months my check engine light has been on. The self diagnostic test showed a series of 43's which indicated multiple misfires in the cylinders. I know that a TSB was put out for bad valve springs in the 97-98s. How do I verify that this is the cause of my issues before I pay to get them fixed?

Thanks guys!
 

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When was the last time the cap/rotor, plug wires, and spark plugs were replaced?
 

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I have a 97 TJ with only 100k miles on it. I purchased it in September of 2014 and for the last few months my check engine light has been on. The self diagnostic test showed a series of 43's which indicated multiple misfires in the cylinders. I know that a TSB was put out for bad valve springs in the 97-98s. How do I verify that this is the cause of my issues before I pay to get them fixed?

Thanks guys!
Multiple 43 codes is exactly what my '97 TJ had and they were not cured until I replaced the valve springs. That was after I had replaced everything else including the spark plugs, distributor cap, rotor, ignition wiring, fuel injectors, fuel injector wiring harness, clockspring, and ECM. I only bought the plugs, distributor, rotor, and ignition wiring, Jeep engineering provided everything else at no charge. They contacted me '98 or so after reading about all my 43 codes and hadn't yet found the problem was the valve springs. It was maybe a year later they published the TSB instructing that a bad batch of valve springs was the problem and needed to be replaced along with cleaning the combustion chambers.
 

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Discussion Starter · #4 ·
About how much was your valve spring repair? My mechanic didn't want to do it unless they knew for sure that is what it was. I might just take it to the jeep dealership in town...
 

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Discussion Starter · #5 ·
Also, did you notice a decrease in fuel economy with the valve spring issue?
 

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It's been years but I think I paid $86 for new springs and $150 to a local mechanic to replace them. I don't pay enough attention to my mpg to have noticed any difference.
 

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Discussion Starter · #7 ·
Thanks so much for the help!! Do you know how quickly I should get it fixed?
 

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Discussion Starter · #8 ·
I mean, can I wait a while or should I fix it asap?
 

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As asked in 1 of the above Posts How old are Spark Plugs-Cap-Rotor & Spark Plug Wires? if you don't know start with replacing those as Maintence, Use Quality Parts & either Champion or Autolite Plugs
 

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Misfires that are causing a check engine light could lead to catalyst damage it too much unburned fuel is getting to them. I wouldn't wait too long.
 

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The longer you wait to replace the valve springs, the more likely it is you will need a valve job to completely fix the problem.
 

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The longer you wait to replace the valve springs, the more likely it is you will need a valve job to completely fix the problem.

Jerry, since you've had direct contact with Jeep about this, I've got a question about this issue maybe you can answer. The procedure to repair the misfires is new valve springs and a de-carbon procedure of the combustion chambers.

Do you know if the weak valve springs themselves are what cause the misfires and the de-carbon procedure is a precautionary measure to clean out the combustion chambers after it's been misfiring?

Or are the weak valve springs allowing carbon buildup and the carbon buildup itself is what causes the misfires?
 
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