Backfire / popping noise when started

J

Jsholmes

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Oct 22, 2021
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11
Location
Florida
Hello to all,
On my wife’s 2008 jk 3.8 with 180,000 I had just finished replacement of cracked stock exhaust manifold. Stock was replaced with a set of short headers, while Apart I also changed spark plugs, plug wires (live wires) along with a new Ignition coil( screaming demon) or better know as the Firepower kit from performance distributors. After completion when I started vehicle almost sounded like a backfire shortly after check engine light came on with a code of P0300.
Plugs were gaped to Performance distributors recommendation of .065
 
Alot of the time if you don't use OEM parts on the Jeeps they will reject them. Try doing a ECM reset to see if maybe the ECM can relearn with the new parts.
 
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So I’ve reset the ecm twice and problem still Exist. Also have all wires in correct location as everything was number. Back to the drawing board for now
 
You can hear what the vehicle is doing just after start up. Any suggestions would be greatly appreciated
 

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If it didn't do that before you put those parts on then it has to be something you replaced and the Jeep doesn't like it.
 
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So just finished changing spark plugs and insuring gap was correctly set and problem still occurring. Like it’s backfiring Out the cold air intake. WTH is going on this Jeep has it out for me lol
 
Last edited:
BLACKJKU said:
Check Engine Light
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Being I replaced cracked stock exhaust manifold was Shorty headers would that make an 02 sensor not read correctly or bring to light they are bad? Is it possible the O2 sensors are bad or CC are bad causing p0300 code? Not understanding what’s happening as it was fine before tune up now the CEL flashes and that’s the code I’m getting
 
Jsholmes said:
Being I replaced cracked stock exhaust manifold was Shorty headers would that make an 02 sensor not read correctly or bring to light they are bad? Is it possible the O2 sensors are bad or CC are bad causing p0300 code? Not understanding what’s happening as it was fine before tune up now the CEL flashes and that’s the code I’m getting
Click to expand...

The o2 sensors will have there own code and it will tell you which one of the 4 is bad. I have long tube headers on mine and the only thing that had anything to do with them was the high flow cats. I kept getting codes for the down stream o2's so I had to put foolers on them.
 
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