Code 33 and 42 after swapping T-Body and plenum.

[G-Force]

After swapping stock throttke and plenum for a 62MM, I am now getting malfunction code 33 (maf sensor high) and code 42 (open est/bypass cir.)
I notice that there is no IAC reading when I hook up mu scan tool. Also the sensor below that throttle cable that screws into the manifold, top portion of it came apart while I was working there. The motor is idling a bit higher than normal. Everything was working fine before I made the swap. Any can help me out on what's code 42 or any insight how I can go about and bring my car back to normal again would be greatly appreciated. Thanks.

 

[RUQWKNF]

Go here for trouble code quick reference info.

Malfunction Codes Reference


Code 33:


Trouble Code 33 indicates that the Mass Air Flow (MAF) sensor is reporting more air is entering the engine than makes sense based on RPM and TPS. The MAF sensor produces a frequency output; around 30 Hz at idle to 150 Hz under acceleration. The frequency varies proportionally to airflow. The ECM monitors the frequency and thus determines airflow into the engine. Typical idle MAF is 5 to 7 grams per second.

The conditions for setting this code are:

* no Code 21 or 22 (TPS Error) present, and
* the air flow reported is > 40 grams per second, and
* TPS indicates < 10% throttle position, and
* the engine speed is 1400 RPM or less, and
* the above conditions exist for over 5 seconds.


Typical causes for this code include:

1) Faulty MAF-to-ECM connection
2) Exceedingly noisy spark plug wires
3) Poor routing of MAF harness (i.e. near coil packs)
4) Maladjusted TPS sensor
5) Defective MAF sensor
6) Defective ECM
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Code 42
Trouble Code 42 indicates that there may be a malfunction in the Electronic Spark Timing (EST) system.

During cranking, the timing is controlled by the ignition module while the ECM monitors the engine speed. When the engine speed exceeds 400 RPM, the ECM sends a BYPASS signal to the ignition module which switches the timing to ECM control. The ECM calculates what the timing should be then "tells" the ignition module via the EST circuit.

An open or ground in the EST circuit will stall the engine and set a Code 42. The engine can be re-started but it will run on ignition module timing.

The conditions for setting this code are:

* System in BYPASS mode but the ignition module is still controlling timing

- or -

* Engine speed > 600 RPM with no EST pulses (ECM controlled timing) going to the ignition module for 200 msec.


Typical causes for this code include:

1) BYPASS line is open or grounded
2) EST line is open or grounded
3) PROM or CALPACK not seated properly in the ECM
4) Poor connections between ignition module and ECM
5) Poor routing of EST harness and/or poor quality ignition wires (EMI induced electrical noise)
6) Faulty or incorrect ignition module
7) Faulty ECM




When you say the sensor that screws into the manifold, are you refering to the coolant fan temp sensor?, or the IAC valve that screws into the IAC housing?

The coolant fan sensor has a mushroom head and the IAC valve has a 4 prong weather pack connector.

Also, whenever you install a new or any t-body that doesn't have the minimum air bleed screw in same spot than the one you took off the car, you will have to do IAC reset and TPS reset proceedures. That set screw is not an idle screw, it's the minimum air bleed screw that is used to properly sync your IAC.

Go here for that info.

IAC Reset Procedure

My guess is your TPS needs adjusting as well as the IAC after reading those trouble codes.

Hope this helps.

Patrick

 

[G-Force]

Its the fan temp sensor that came apart.
I am trying to set the IAC but on my otc the IAC is 000 at all times. TPS is set at .44.

 

[XLR8]

I would check the connnection of the wire harness at the coil pack. Maybe it's loose or a pin was ben when reinstalling or a wire/wires were pinched.

 

[G-Force]

I am going tru this thing with a fine tooth comb to figure out what I messed up on. Still getting code 42 but the car is idling nornal again since I swapped the new autzone TPS back to the stock GM tps.