There is absolutely no way you're going to make this engine run properly with missing parts. I can't imagine what kind of deal you made with your mechanic but he should have known better. Turbocharged and supercharged engines have a lower compression ratio which those air pumps make up for. You need the supercharger to stuff the correct amount of air into the cylinders. Atmospheric pressure isn't going to do it.
You won't find any professional willing to help with removed catalytic converters. It is now illegal for us to work on the truck. The front oxygen sensors will still work properly and will tell the Engine Computer how to adjust fuel metering but with the missing converters, no change in the composition of the exhaust gas will take place between the front and rear O2 sensors. The Engine Computer watches the switching rate between too lean and too rich. That switching takes place about twice per second at the front sensors, but when the catalytic converters are working correctly, the switching takes place at the rear sensors perhaps once every minute or two. As it is now, both sensors will switch at exactly the same rate which is going to set a diagnostic fault code for "catalytic converter efficiency". That will turn on the Check Engine light. Since the light will always be on, you'll never know if a different, minor problem is detected that could turn serious if neglected.
Also, once those converter codes are set, some self-tests will be halted because the computer knows it can't rely on the O2 sensors to provide proper test results. You could have some running problems that won't even be detected until the converters are replaced.
Saturday, December 27th, 2014 AT 4:57 PM