A heads up for y'all.

[hagar]

The problem with engine modules is they don't know there is a problem often. For example, if you try to start a vehicle with a coolant temp sensor shorted to -40, the engine will never figure out it's a problem, and will add insane fuel and not run. We like to think they are much smarter than they are, but in the end, they are just dumb number inputs. There is absolutely ZERO reasoning or common sense in an efi system. They don't see a sensor being off as a problem, they just go with it and change everything as if it was reporting a proper signal.

 

[Marky Dissod]

The problem with engine modules is they don't know there is a problem often.
For example, if you try to start a vehicle with a coolant temp sensor shorted to -40, the engine will never figure out it's a problem, and will add insane fuel and not run.
We like to think they are much smarter than they are, but in the end, they are just dumb number inputs.
There is absolutely ZERO reasoning or common sense in an efi system.
They don't see a sensor being off as a problem, they just go with it and change everything as if it was reporting a proper signal.

This is not always true.
For example, if the coolant temp sensor says -40, and the intake air temp sensor does NOT, and then the engine starts,
and the coolant temp does not rise while the intake air temp rises,
that's a trouble code right there.

If the rear O2 sensors say over 300mV for an extended period of time, and neither Power Enrichment nor CAT Enrichment have been activated,
that's a trouble code right there.

If the expected coordination between the crank and the cam is off by more than a few min, that's a misfire.

Some trouble codes are more easily definable than others. I do wonder why GM added a humidity sensor ...

 

[hagar]

This is not always true.
For example, if the coolant temp sensor says -40, and the intake air temp sensor does NOT, and then the engine starts,
and the coolant temp does not rise while the intake air temp rises,
that's a trouble code right there.

If the rear O2 sensors say over 300mV for an extended period of time, and neither Power Enrichment nor CAT Enrichment have been activated,
that's a trouble code right there.

If the expected coordination between the crank and the cam is off by more than a few min, that's a misfire.

Some trouble codes are more easily definable than others. I do wonder why GM added a humidity sensor ...

I have never seen a coolant temp corelation code before, only open circuit codes. I have however seen coolant temp sensors report improperly and not throw a code. I manipulate the air intake temp sensor in some applications so it shows vastly different than it should, and it never trips a code. Cam and crank sensors work together yes.