03 5.3 bucking/backfiring

<div class='quotetop'>QUOTE(Boss302 &#064; Mar 18 2007, 03&#58;49 PM) [snapback]86596[/snapback]</div>

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its throwing a ses light for the o2&#39;s. nothing for the fuel pressure though. i did find that the fuel is running through a box of some sort for fuel economy?? but its not plugged in. i may try bybassing it and see what fuel pressure is then. thanks for the help guys. Lee [/b]

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The "box" you are referring to is most likely the sensor for E85 fuel. Was your donor Tahoe outiftted for E85? Have you monitored your O2s for proper operation yet?

<div class='quotetop'>QUOTE(kwkenuf &#064; Mar 20 2007, 03&#58;20 PM) [snapback]86778[/snapback]</div>

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The "box" you are referring to is most likey the sensor for E85 fuel. Was your donor Tahoe outiftted for E85? Have you monitored your O2s for proper operation yet?
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i believe you are correct. i havent monitored my o2&#39;s yet. i run my codes at firestone w/a friend of mine . ill get back to firestone and plug em back in for monitoring.

also check your pcv valve i just read about how a bad one will cause you truck to back fire. just an idea if i&#39;m wrong hopefully someone will chim in. but at least that is a cheap thing to replace even if it doesn&#39;t fix your problem doesn&#39;t hurt your wallet. also good luck looks like you are headed in the right direction.

hope you get it fixed