DansZs

A friend of mine bought an 35th Anniversary Ed. SS and immediately had it shipped to Mecham performance to have mods done to it (this was about 5 months ago). Mecham put a performance exhaust system, headers, 3.73's, and reprogrammed the computer. Ever since then, my friend has had a check engine light on. After calling Mecham, they said that they would send an updated program for the computer. My friend put this new program on the computer and he still has a check engine light on. Next he took it to a dealership to have the codes read and they came out to be:
P0153
P0161
P1133
P1153
The dealership told them the codes were related to the O2 sensors and that the codes were "set" because the car was modified. However, Dennis at Mecham Performance says that the codes are because of the dealership and are not related to anything they did. One more thing--the dealership put the stock program back on the car, but the check engine light still remained. Any ideas on what could be causing the problem?

Thanks


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Daniel
85Z
Stock

96Z--B&B Triflow, F1 CAI, TB Air Foil & Bypass
96 rwhp Dyno #'s
(bone stock)
hp: 256 @4750
torque: 316 @3500

http://www.danszs.freeservers.com
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jgkinsofla

P0153 HO2S Slow Response Bank 2 Sensor 1

Circuit Description

The PCM continuously monitors the Heated Oxygen Sensor (HO2S) activity for 100 seconds. During the monitor period the PCM counts the number of times that the HO2S responds from rich to lean and from lean to rich and adds the amount of time it took to complete all transitions. With this information, the PCM can determine the average time for all transitions. If the average response time is too slow, a DTC will set.

The PCM determines the lean to rich transition when the HO2S voltage changes from less than 300 mV to greater than 600 mV. The PCM determines the rich to lean transition when the HO2S voltage changes from more than 600 mV to less than 300 mV. An HO2S that responds too slowly is most likely defective. Replace the HO2S.

P0161 HO2S Heater Performance Bank 2 Sensor 2

Circuit Description

The PCM supplies a bias voltage (approximately 450 mV) on the Heated Oxygen Sensor (HO2S) signal high and low circuits. When you turn the ignition to the ON position, battery voltage is supplied to the HO2S heater. As the heater reaches the operating temperature, the HO2S voltage responds by changing from a bias voltage range to the normal operation. Typically, as the HO2S reaches the operating temperature, the HO2S voltage goes from a bias voltage to a voltage below 300 mV. Depending on the exhaust gas content, it is possible for the HO2S voltage to go above 450 mV.

The PCM runs the heater test only on a cold start (depends on the cumulative air flow) and only once an ignition cycle. When you start the engine the PCM monitors the HO2S voltage. When the HO2S voltage goes above or below the bias range threshold, the PCM determines how much time it took. If the PCM detects that the process took too much time for the HO2S to enter into normal operating range, this DTC sets. The time the process takes the HO2S to reach operating temperature is based on the amount of air that flows into the engine.

P1133 HO2S Insufficient Switching Bank 1 Sensor 1

Circuit Description

The PCM monitors the Heated Oxygen Sensor (HO2S) activity for 100 seconds. During this monitor period the PCM counts the number of times that the HO2S switches form rich to lean and lean to rich. A DTC P1133 sets when the PCM determines that the HO2S did not switch enough times.

A lean to rich switch is determined when the HO2S voltage changes from less than 300 mV to greater than 600 mV. A rich to lean switch is determined when the HO2S voltage changes from more than 600 mV to less than 300 mV.

P1153 HO2S Insufficient Switching Bank 2 Sensor 1

Circuit Description

The PCM monitors the Heated Oxygen Sensor (HO2S) activity for 100 seconds. During this monitor period the PCM counts the number of times that the HO2S switches form rich to lean and lean to rich. A DTC P1153 sets when the PCM determines that the HO2S did not switch enough times.

A lean to rich switch is determined when the HO2S voltage changes from less than 300 mV to greater than 600 mV. A rich to lean switch is determined when the HO2S voltage changes from more than 600 mV to less than 300 mV.

Seems pretty common with header installs - same problem keeps re-occuring over at www.ls1tech.com. Makes you want to avoid installing headers!

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'99 Z28 A4 BLACK
▪ SLP air lid, K&N filter, air box mod, Borla exhaust, HPP3, 160* stat, Magnecor 8.5 mm wires, NGK TR55 plugs
▪ Pioneer DEH-P77DH, Polk speakers

DansZs

Hey thanks for your help. I'll send this info to him and I'll check out LS1.com

I had no idea that there was a problem with headers on the LS1s!

Thanks again
Daniel