[rfmaster]

I would start with Code 44 (engine lean condition) and address Code 24 after solving Code 44

I am assuming that you have 220-TBI on top of stock 350 crate motor.
First – clear all codes and address code 44 –stumble lean conditions

Code 44
According to GM trouble shooting guides code 44 relates to Oxygen Sensor circuit Lean condition indication. Code 44 is set when Oxygen sensor circuit (412) reads below 250mV for 50 seconds while system operates in closed loop.

If you have a scanner set scanner to Scan and observe when block learn numbers (BLM) at different RPM’s and air flow conditions to determine where Code 44 was set. The BLMs of 150 will cause Code 44 to be set.

What could cause 44

Check O sensor wires – make sure O sensor wire does not contact exhaust. Check sensor ground for a good contact. Check for intermittent contact between connector and sensor.
Make sure that O sensor ground is clean – use specially formulated anti seize compound.

Manifold Absolute Pressure (MAP) Sensor may cause ECM to see lean condition. Temporarily disconnect MAP sensor and if the lean condition is gone replace MAP sensor – around $50.

Lean Injectors: check for fuel contamination such as water in the fuel may set code 44
Check fuel pressure
Exhaust leaks will cause code 44 by letting outside air into the system upstream from O sensor and cause sensor to see lean condition.
Check AIR system – if air pump is injecting air in exhaust when operating in closed loop this will cause O sensor read very lean.


I hope it helps.

//RF