2007 avalanche 5.3L PO 172, 175 & 717

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allstages

2007 avalanche 5.3L PO 172, 175 & 717

I am an ASE tech myself. Have been in the industry for 30 plus years. This one has me stumped! This happens to be my personal vehicle. Vehicle has 245,000 miles. Was purchased with codes. Previous owner replaced coils, injectors, wires and plugs. All A/C delco. This is an AFM engine. Engine did have a very bad lifter noise. The following items were also replaced and relearned. Fuel pmp, MAP, MAF, TPS, COOLANT TEMP SENSOR, EVAP SOLENOID, charcol canister and relearned the alcohol content. I really was not to overly concerned about the input speed sensor, however I made a decision to pull the engine and trans (being that the input sp sensor is behind the pmp) and rebuild the entire engine and transmission. New pistons, cam, lifters, crank cut, cylinder heads reconditioned, oil pump, bearings, oil manifold all 4 O2 sensors & a new ECM. The transmission is also completely new from front to back including a new torque converter, lock up solenoid, input speed sensor and shift kit. There is absolutely nothing that was not replaced on this vehicle. Still same codes. right bank rich and input speed sensor. I replaced the TCM and the vehicle will not even move! reinstalled original TCM at least for now. I have been on the phone with 2 technical support companies and nothing. Cannot not figure out. The LTFT is -30% on both banks but only the right bank kicks a code. I have checked voltages and grounds. Obviously I'm missing something. What? Possible bad cat's? I noticed that it will only turn on check engine light when city driving. Went for a 2 hr drive last week and nothing. Ran perfect! When you get to a decell (city driving) it will turn on traction control and I know shortly after the check engine light will illuminate. I know it's the PO717 but it has a very harsh 1-2 shift. Good thing this isn't a customers vehicle. We'd be up to 100k by now. LOL.

Status: Open Sep 25, 2023 - 06:01 PM

Chevrolet

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Grace_CarParts.com

Sep 26, 2023 - 10:40 PM

Hello!

It is very strange that you are still getting the PO172, PO175, and PO717 codes after replacing all of those parts and rebuilding the engine and transmission. Here are a few more things to check:

Exhaust leaks. Make sure there are no exhaust leaks between the exhaust manifolds and the catalytic converters. Exhaust leaks can cause the O2 sensors to read incorrectly, which can lead to rich fuel mixtures.
Fuel pressure. Check the fuel pressure to make sure that it is within the correct range. High fuel pressure can cause rich fuel mixtures.
O2 sensor heaters. Make sure that the O2 sensor heaters are working properly. The O2 sensor heaters bring the O2 sensors up to operating temperature quickly, which is important for accurate readings.
Wiring. Check the wiring to the O2 sensors and the TPS to make sure that it is not damaged or corroded.

If you have checked all of these things and you are still getting the same codes, then it is possible that you have a bad catalytic converter or a bad ECM.

Here are some additional tips for troubleshooting:

Use a scan tool to monitor the live data from the O2 sensors and the TPS. This can help you to identify any problems with these sensors.
Perform a smoke test to check for exhaust leaks.
Measure the fuel pressure with a fuel pressure gauge.
Check the resistance of the O2 sensor heaters with an ohmmeter
Check the continuity of the wiring to the O2 sensors and the TPS with a multimeter.

If you are still having trouble diagnosing the problem, you may want to seek help from other qualified mechanics. As the saying goes, more heads are better than one.

I hope this information is helpful. Please let us know if you have any other questions. Have a nice day

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