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I have a 98 GMC Sierra 5.7... I recently cut the cats off and removed to 02 sensors, after that it start bucking at times while driving. It's throwing the code PO340. I've replaced the about everything under the hood and it's still doing it. Could the wiring connections to the cam positioning sensor be causing this? I'm at a complete loss. Thanks for any help or suggestions.
 

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When you removed the O2 sensors, did you just unplug them or did you do a bypass wiring to fool the ECU into thinking they were still there working?

Blue Mule
 

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Did you remove all 4 sensors, or just the 2 rear sensors. No mater what, your truck will not run rite without the 02 sensors. Front sensors set fuel trim levels. Rear sensors tell the ECM that the cats are working. If you just remove the rear sensors, you still need to do something about the ECM. Ether make or but some 02 simulators,or have them tuned out. As for the front sensors, you can NOT remove them,,,can NOT, unless you do a card swap.
 
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