The right compression parameters

[dochidalgo]

My 97 Trans am with 56k miles old and almost sock engine ( the head gaskets are the 0.039"), was working almost fine the last weekend, with brand new fuel injectors and spark plug wires. The DTC P0300 was gone, but a pair of DTCs showed: P0154 again and new P0141. For the first one the problem stays there in spite of interchange the 02 sensors, and the Evap purge selenoid was banned replacing 2 pipes.......but....the DTC P0300 came back!!
Same cylinder in hot engine condition and I could listen a tapping noise which souce is not the valvetrain, is coming from or sourrounding AIR pump area, I guess. Tomorrow, the GM dealer mechanic is going to perform a compression testing and I would like to know the right parameters.
It has been a mechanic nightmare......guessing, untesting, purchasing, spending, and the problem in my daily car is there...
Next guessing....the opticrap....or the ICM maybe?...or the cranck position sensor perhaps....the patient already had passed away if the car was a human being...frustating matter .... I'm going to give up with this car of mine...just venting... sorry
Thanks for your imput
Dochidalgo

[97LT1Z28]

How's the fuel quality in Mexico? I grew up in McAllen, TX on the Mexico Border. I spent a lot of time across the border and one thing I can always remember was that the fuel quality wasn't the same as in the United States. I remember when I would fill-up my tank in Mexico, my engine would sputter and the fuel filter would clog and need to be changed.

The LT1 and LS1 engines are finely tuned and operate on precise engineering. If the fuel quality is low, you'll get dirty injectors (I see that you've done some work on your injectors in your previous posts), frequently clogged fuel filters, sediment in your fuel tank, etc -- this could be the cause of all your problems.

Just a guess.

[Injuneer]

You may have codes mixed up:

P0141 = drivers side after-cat O2 sensor heater circuit malfunction.

Is it possible you meant to type P0441 which indicates a purge solenoid problem?

P0154 = passenger side pre-cat sensor circuit - no activity. Could be a wiring problem, as simple as the plug pins not making good contact. If you swap the sensor and the problem doesn't follow the sensor, its a wiring problem.

[dochidalgo]

Ohh, yes Fred, I mistype the DTC, You're right, EVAP puge problem, but dissapeared replacing the cracked hoses. The 02 sensor was gone today cleaning the connectors.
But the random misfire is there yet.
Thanks for your concern
Dochidalgo