2005 5.3L Lean Codes
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Teching In
Joined: Sep 2019
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2005 5.3L Lean Codes 2005 5.3l vortec that has major bucking and surging at 40-45 mph and throws both P0171 and P0174 lean codes for both banks.
I took the 2005 5.3l vortec and 4l60e transmission out of Suburban and I put it into a 1967 Fj40.
It fired right up after the swap and idles completely fine. No DTC's thrown at idle. It drives fine in first second and third gear (Has somewhat rough shifting but nothing that I wouldn't expect since the ECM was programmed for a tire size of 37in but i have 33's on it currently while I am am saving for 37's) but once it gets to where it should switch into OD and have the RPMs drop it starts bucking and surging and throws the P0171 and P0174 codes. It wont let me push through it if I floor it either. It also does it when I take it out of OD and put it into D it still does the same thing.
I originally thought that it was the TCC wire that i didnt have connected and the torque converter was locking and unlocking but now its hooked up and working the way it should but did not solve issue. I then thought it was a vacuum leak from the intake manifold so I replaced the intake and nothing helped. I cleaned the MAF sensor, used brand new O2 sensors, replaced MAP sensor and other things here and there.
Nothing seems to fix this issue. Does anyone have experience with this issue? I am at a loss and just hoping its a sensor issue and not a TC issue or warped intake.
Note:
Vehicle is Flex Fuel and the ECM still has all the flex fuel programming stuff on it but i am not running a flex fuel sensor in the vehicle. No DTC's have been thrown regarding this though.
Also I am using a Bosch 044 inline fuel pump with a speedway motors ls style fuel regulator that says is 58psi but i have not actually tested the pressure.
I took the 2005 5.3l vortec and 4l60e transmission out of Suburban and I put it into a 1967 Fj40.
It fired right up after the swap and idles completely fine. No DTC's thrown at idle. It drives fine in first second and third gear (Has somewhat rough shifting but nothing that I wouldn't expect since the ECM was programmed for a tire size of 37in but i have 33's on it currently while I am am saving for 37's) but once it gets to where it should switch into OD and have the RPMs drop it starts bucking and surging and throws the P0171 and P0174 codes. It wont let me push through it if I floor it either. It also does it when I take it out of OD and put it into D it still does the same thing.
I originally thought that it was the TCC wire that i didnt have connected and the torque converter was locking and unlocking but now its hooked up and working the way it should but did not solve issue. I then thought it was a vacuum leak from the intake manifold so I replaced the intake and nothing helped. I cleaned the MAF sensor, used brand new O2 sensors, replaced MAP sensor and other things here and there.
Nothing seems to fix this issue. Does anyone have experience with this issue? I am at a loss and just hoping its a sensor issue and not a TC issue or warped intake.
Note:
Vehicle is Flex Fuel and the ECM still has all the flex fuel programming stuff on it but i am not running a flex fuel sensor in the vehicle. No DTC's have been thrown regarding this though.
Also I am using a Bosch 044 inline fuel pump with a speedway motors ls style fuel regulator that says is 58psi but i have not actually tested the pressure.
Thread Starter
Teching In
Joined: Sep 2019
Posts: 7
Likes: 0
Fuel pressure is good (58 psi). Changed intake gasket and still have issue. Both banks running lean with bucking at around 40 mph. Both banks running around 25% lean per scanner data. Any other ideas or inputs?
