Hello All,
I’ve been searching forever it feels with no luck. I bought a used 07 Tahoe with a flex fuel 5.3. 165k miles. Decent shape but as I look into it more, maintenance was sub par. It had P0430 and a bunch of EVAP codes when I got it. Replaced the cats since it was rattling. 4 new GM O2 sensors. Cleaned the throttle body, new MAP and MAF sensors, new thermostat (was sticking), fluids etc. Runs fine until P0420 and P0430 codes pop then it runs like crap. Clear the codes and back running fine. When the codes pop it’s the same type of driving; slow speed coming to a stop in a parking lot. Feels like the converter is staying locked up and wants to die. Transmission doesn’t seem to be an issue; I think. Freeze data shows negative long term fuel trims between -6 and -10 usually at between 515 and 530 RPM at 0 MPH. Tried the spacer fix and no difference. Plugs have shown no evidence of coolant or other issues that I can see. Decided to pull the injectors and clean them. A couple of them were pretty crappy but in the end all had good spray patterns. When watching live data the long term fuel trims at cruise speeds are in the high negatives. Ranging from -12 to -18 on both sides. Post cat O2 readings are in the .09 to .1 range, which show lean (correct?). You can now feel a really significant surge. Acceleration is just fine though. Checked fuel pressure at idle and it’s 55. I read one post that leads me to look closer at the fuel pump assembly but not looking to throw more parts at it if I don’t have to. Any other ideas for things to check? Thanks.
I’ve been searching forever it feels with no luck. I bought a used 07 Tahoe with a flex fuel 5.3. 165k miles. Decent shape but as I look into it more, maintenance was sub par. It had P0430 and a bunch of EVAP codes when I got it. Replaced the cats since it was rattling. 4 new GM O2 sensors. Cleaned the throttle body, new MAP and MAF sensors, new thermostat (was sticking), fluids etc. Runs fine until P0420 and P0430 codes pop then it runs like crap. Clear the codes and back running fine. When the codes pop it’s the same type of driving; slow speed coming to a stop in a parking lot. Feels like the converter is staying locked up and wants to die. Transmission doesn’t seem to be an issue; I think. Freeze data shows negative long term fuel trims between -6 and -10 usually at between 515 and 530 RPM at 0 MPH. Tried the spacer fix and no difference. Plugs have shown no evidence of coolant or other issues that I can see. Decided to pull the injectors and clean them. A couple of them were pretty crappy but in the end all had good spray patterns. When watching live data the long term fuel trims at cruise speeds are in the high negatives. Ranging from -12 to -18 on both sides. Post cat O2 readings are in the .09 to .1 range, which show lean (correct?). You can now feel a really significant surge. Acceleration is just fine though. Checked fuel pressure at idle and it’s 55. I read one post that leads me to look closer at the fuel pump assembly but not looking to throw more parts at it if I don’t have to. Any other ideas for things to check? Thanks.
