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Old 01-11-2022, 12:19 AM   #2
fdryer
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Join Date: Jan 2006
Location: NYC
Posts: 45,795
 

2003 L-Series 3.0L Sedan
Default Re: Help with understanding codes

There are many sources of information for error codes. Before suggesting links or attempting to explain them by anyone, perhaps some questions need to be asked without presumptions of your work as neither correct or incorrect.

Are there any reasons to explain why the timing chain broke? Lack of oil, lack of maintenance, inheriting this car from another owner and problems not revealed until you took ownership and discovered problems? The GM 2.2L ECOTEC engine is used in several GM models so there's a history with this engine, good and bad.

Without presuming a great a rebuild being correct, may I ask verification of this rebuild with valid compression values? If compression is at least 165 psi on all cylinders then timing, cylinder head, and valves assure a mechanically sound engine. The EFI and exhaust system would be two areas of concern.

The EFI system uses sensors to tell the engine computer what's going on and allows it to control the engine. Error codes can be misleading sometimes due to something indirectly affecting sensor operation, making a sensor fail when it didn't. Sensor diagnosing and troubleshooting can help by testing a sensor using a multimeter, applying heat or cold to measure output values, and measuring some for resistance values. If costs don't matter, replacing sensor parts is sometimes more expedient.

The exhaust system sometimes choke off exhaust flow and can generate odd error codes without rhyme or reason. The catcon can disintegrate internally to severely restrict exhaust flow creating the equivalent of engine constipation by backing up exhaust flow, creating a weak engine. One of the simplest troubleshooting methods suspecting exhaust choking engine running would be removing the exhaust manifold mounted O2 sensor before/upstream from the catalytic converter. This allows an alternate exhaust path. While loud, a brief drive around the block either shows immediate engine improvement or not. An immediate surge in power would imply the catcon is severely blocking exhaust flow.
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