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Ask Chad Farhat Your Own Question
Chad Farhat
Chad Farhat, ASE Certified Technician A6 - Electrical / Electronic systems A7 Heating / Air conditioning systems
Category: Oldsmobile
Satisfied Customers: 3487
Experience:  Owner at Carolina Auto Service & Sales , 20 years Experience in Foreign & Domestic vehicles
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On cold start it doesn't want to stay running and then also

Customer Question

On cold start it doesn't want to stay running and then also and it will put him stay way up on RPMs then stumble again again
JA: Have you checked the battery, particularly the terminal connections? Are they corroded?
Customer: Yes I check battery connections
JA: What is the model/year of your Oldsmobile?
Customer: 02 Oldsmobile Alero with a 3/4 in it
JA: Are you fixing your Alero yourself? What have you tried so far?
Customer: Code scanner said map sensor replace it replace the idle air control sensor
JA: Anything else you want the mechanic to know before I connect you?
Customer: No
Submitted: 8 months ago.
Category: Oldsmobile
Expert:  Chad Farhat replied 8 months ago.

Hi, I'm Chad. Welcome to JustAnswer. I'm reviewing your question and I will be posting your reply ASAP.

Customer: replied 8 months ago.
Basically it will Surge and between low RPMs and high RPMs
Expert:  Chad Farhat replied 8 months ago.

hey how are you

1- is there a check engine light on now

2- have you scanned and retrieved fault code

3- usually the cold start issue will be ECT(engine coolant temp sensor (the sensor for the computer )

in morning when engine is cold ,it take it info from , the ect sensor, map sensor etc.. ,when the vehicle reaches operating temp, it switches to oxygen sensor readings , usually if run good on operating temp but not when cold, that ect sensor could be telling ecu the car is colder or hotter that it is and it mess up your air fuel ratio

4- the surging ,part could be in take manifold leaking ,or a vacuum leak, spray starting fluid on COLD ENGINE ONLY,and see if the engine surges up,if it does you have a vacuum leak.

If at any point during our conversation you like to speak to me on the phone ,feel free to ask me or you can request it on the screen at your convenience and I will call you right away.

Please let me know

Thank You

Chad Farhat

ASE Certified Technician

Expert:  Chad Farhat replied 8 months ago.

if you can get me some fuel trim readings , short term & long term fuel trims ,i can be more accurate for you


Customer: replied 8 months ago.
St1.6. 2.3. Lt-2.3
Customer: replied 8 months ago.
St. 4.7. Lt2.3
Expert:  Chad Farhat replied 8 months ago.

those fuel trims looks good, i don't see vacuum leaks

what is the ECT reading and also tell me what is the temp showing dash, does it match you scanner reading for ECT ?

Customer: replied 8 months ago.
Temp matches
Customer: replied 8 months ago.
This time it ran like crap and once it warms up
Customer: replied 8 months ago.
Did did you get my new fuel trims pictures I want to start a running like crap I was -20 something on both
Expert:  Chad Farhat replied 8 months ago.

the fuel trims - 20 , tells me , you are running rich ,and the pcm pulling fuel away 20% ,almost to the 25% limit

1-when running rich it mean too much fuel & PCM PULLING FUEL AWAY ,


check fuel pressure regulator , fuel injector leaking ,vacuum leaks, MAf Sensor.

Customer: replied 8 months ago.
Fuel pressure is good about 50 pounds pull the fuel pressure regulator off gain an extra 5 pounds so I don't think the issues there air filters almost new so
Expert:  Chad Farhat replied 8 months ago.

For A 02 Buick Alero with 3.4 liter these are the Fuel specs

1-Fuel Pressure

Key On Engine Off (KOEO) 52-59 psi, (so if you are at 50 you are low on your fuel pressure)

when the fuel regulator is off , you need to above 60 not an extra 5 pounds , take the fuel pressure regulator & inspect diaphragm for leaking internally.

2-Fuel Injector Pressure Drop
review the link i sent you for fuel injector balance test

Pressure Drop

1.5 psi

Fuel Injector Balance Test Example (Typical)

If the pressure drop value for each injector is within 1.5 psi of the average drop value the fuel injectors are flowing properly.

Expert:  Chad Farhat replied 8 months ago.

if you scan it again right now , what is the first fault code listed in the scanner ?

Customer: replied 8 months ago.
P0137 oxygen sensor circuit low voltage bank 1 sensor 2
Customer: replied 8 months ago.
Next one is p1106 manifold absolute pressure sensor circuit
Expert:  Chad Farhat replied 8 months ago.

what other codes are left ?

Can you Run this below test ? let me know

i sent you 2 links ,open them up and follow the troubleshoot steps & see where it leads us

DTC P0137

CIRCUIT DESCRIPTION Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the vehicle is first started the powertrain control module (PCM) operates in an Open Loop mode, ignoring the HO2S signal voltage when calculating the air-to-fuel ratio. The PCM supplies the HO2S with a reference, or bias, voltage of about 450 mV. The HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage once in Closed Loop. A high HO2S voltage output indicates a rich fuel mixture. A low HO2S voltage output indicates a lean mixture. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature, and provide an accurate voltage signal. The HO2S 2 is used for post catalyst monitoring. This DTC will set if the HO2S 2 voltage remains below a calibrated amount for an excessive amount of time. The HO2S 2 has the following circuits: ^ HO2S 2 high signal ^ HO2S 2 low signal ^ HO2S 2 heater ignition voltage ^ HO2S 2 heater ground CONDITIONS FOR RUNNING THE DTC ^ DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0410, P0440, P0442, P0443, P0446, P0449, or P1441 are not set. ^ The system voltage is between 9-18 volts. ^ The system is in Closed Loop. ^ The air/fuel ratio is between 12.0-16.5. ^ The throttle angle is between 3-40 percent. CONDITIONS FOR SETTING THE DTC The DTC will set if either of the following conditions are present for up to 2.5 minutes: ^ The HO2S 2 signal voltage remains below 30 mV during Closed Loop operation. ^ The HO2S 2 signal voltage remains below 550 mV during power enrichment (PE) mode. ACTION TAKEN WHEN THE DTC SETS The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the operating conditions to the Freeze Frame and updates the Failure Records. CONDITIONS FOR CLEARING THE DTC ^ The PCM turns OFF the MIL lamp after 3 consecutive ignition cycles that the diagnostic runs and passes. ^ A current, DTC last test fails, clears when the diagnostic runs and passes. ^ A DTC stored in history clears after 40 warm-up cycles, if no failures are reported by this or any other emission related diagnostic. ^ A scan tool can be used to clear the DTC.

The numbers below refer to the step numbers on the diagnostic table. 2. The HO2S 2 voltage may default to the bias voltage. The DTC should be cleared and the Freeze Frame/Failure Records data recorded before proceeding. A normally functioning HO2S 2 voltage signal will fluctuate above and below the bias voltage amount. The action in the test step should result in a visible reaction from the HO2S 2 output. 4. A voltage reading other than bias voltage in this step indicates a short circuit condition in the high signal circuit. 7. The conditions listed in the table may contribute to the failure of the HO2S. The conditions listed apply only to this type of failure.

Expert:  Chad Farhat replied 8 months ago.

Troubleshoot steps DTC 137

Expert:  Chad Farhat replied 8 months ago.

Please let me know if you need anything else on it, just reply back and we will continue

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Thank You
Chad Farhat
ASE Certified Technician

Expert:  Chad Farhat replied 8 months ago.

Let me know if you need anything else on it , just reply back here & we can continue.

if you are good , Please Kindly rate me.

Hope I was helpful to you

A 5 Star Positive Rating is Much Apreciated

This Post Will Stay Open for You To Come back and Ask me Any Follow Up Question You May have on this issue , even after you rate me

Thank You

Chad Farhat
ASE Certified Tedchnician

Customer: replied 8 months ago.
My customer was just sick and tired of spending money on it so he left
Expert:  Chad Farhat replied 8 months ago.

oh i man i get those sometimes:) .no worries