O2 sensor responsible for P0171?

[750iClown]

Originally Posted by M_Bimmer

Take your engine cover off the top, snap a picture and post....I'll draw a line where the Lambda senor pre-cat's are.....the post-cat requires you to remove the intake filter housing and plenum off the rear of the engine to get to the wires and sensor, but if you take this assembly off and take a picture, I can draw another line where the post-cat Lambda sensor is located.

BTW, to take off the intake filter assembly from the engine, it's easy. Loosen the intake plenum pre-filter (there should be two large hose clamps - just loosen one on each side of the engine). Lift up on the rear of the complete assembly - this is the hardest part as there is a heat shield mounted on the underside of the air boxes to protect them from the CAT's.

The airboxes sit on 4 mounts similar to your engine cover, but only larger.

You need to tilt the rear of the air box assembly toward the front of the vehicle first to clear the cowling. then disconnect the intake tubes...then it should just lift out.

A PITA the first time you do it...it will take you 2 minutes every time afterwards.

Note: If you need TIS documentation (included with ISTA) between now and getting your ISTA version running, I can provide.

Here you go. Pic of the engine bay and my new baby sitting in the garage.

https://photos.app.goo.gl/nvTb14UFoWPRKXyLA

https://photos.app.goo.gl/4MgDBFGAur3VUSuk6

[M_Bimmer]

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[M_Bimmer]

You'll have to pull the turbo heat shield off and take a shot down the CAT's which should sit pretty close to the firewall to see the post-CAT lambda sensors.

[750iClown]

Originally Posted by M_Bimmer

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Thank you. I had a feeling about those being the pre-cat O2 sensors. Is Bank 1 drivers side or passenger side of vehicle? I will see what ISTA says first before deciding to purchase a new O2 sensor. The interface cable for that is coming in on Thursday.

Also, where are the MAF sensors, as well as PCV? Let me know if you know that.

[750iClown]

Originally Posted by M_Bimmer

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ISTA cord has arrived.

https://photos.app.goo.gl/oYS54C1ENnoVVzRbA

[750iClown]

Originally Posted by M_Bimmer

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Do you have any info on how I can get the free version of the software? I went to Bimmerfest and I think I found a thread where you request a link based on your model vehicle. I posted there. Is there another way?

[M_Bimmer]

Originally Posted by 750iClown

Do you have any info on how I can get the free version of the software? I went to Bimmerfest and I think I found a thread where you request a link based on your model vehicle. I posted there. Is there another way?

If you PM shawnsheridan on either forum, he'll respond with the link to download ISTA.

[shawnsheridan]

Originally Posted by M_Bimmer

If you PM shawnsheridan on either forum, he'll respond with the link to download ISTA.

He found me.

[750iClown]

Originally Posted by M_Bimmer

If you PM shawnsheridan on either forum, he'll respond with the link to download ISTA.

Ok so here are some screen shots. I am trying to figure out where to go next. I do see the step by step when you click on the fault codes in the "Fault Memory" bank and then select "Show Fault Code". In said step by step aka "Measure in Service", it tells you to look for faults in various items. In this case with code 118001- "Mixture Control: Fuel-air mixture too lean", it suggests to look for faults for the following: (do you have suggestions for going about this, mainly, how to find codes/faults for these particular items in ISTA?)

- Oxygen sensor before catalytic converter
- Hot film air mass meter
- Intake pipe pressure sensor
- Intake air temperature sensor
- Electromotive throttle actuator
- Fuel tank vent valve
- Camshaft sensor
- High-pressure fuel system
- Low-pressure fuel system
- Valvetronic intake adjuster
- Voltage supply sensor system/actuator 5 V
- Ethanol sensor (only in E100 vehicles)

then says....

Check air intake system for tightness, checking the following components as well at the same time:

- Crankcase ventilation
- Oil filler cap
- Oil dipstick
- Tank ventilation system
- Brake servo
- Cylinder head cover
Check exhaust system for leak tightness.
Rule out poor fuel grade.
Check injectors with the test module for misfiring detection and replace if necessary. Then reset adaptations.
Breakdown instruction
- The engine operates in its emergency program.
- Lack of power.
- Rough engine running.

Service instruction
- Reset mixture adaptation after a repair.

https://photos.app.goo.gl/5u1aCZa1cUvF5onk9
https://photos.app.goo.gl/9f5CXtxZzYHfDTYJA
https://photos.app.goo.gl/Yq4WWPyZAY1H6ay3A

[M_Bimmer]

750iClown, congratulations on getting ISTA up and running.

Here is the sequence of things I'd do:

1. Clear ALL fault codes. By clearing all codes, the permanent faults should remain, and the number of yellow colored ECU's should be reduced.

2. Post the codes that remain

3. In service measurement = while running the engine, make measurements and compare those measurements with ISTA's documentation for expected values.

Remember, when measuring O2 sensors, the engine must be at operating temperature. Ignore anything before this point.

Post voltage values for each lambda sensor (graph would be better). Pre-cat O2's should be a steady voltage below 1V...while your post-cat O2's voltages should be wandering around to support fuel trim...so if the post-cat 02 voltage is steady state, I'd call that bad.

check in at this point.

[750iClown]

Originally Posted by M_Bimmer

750iClown, congratulations on getting ISTA up and running.

Here is the sequence of things I'd do:

1. Clear ALL fault codes. By clearing all codes, the permanent faults should remain, and the number of yellow colored ECU's should be reduced.

2. Post the codes that remain

3. In service measurement = while running the engine, make measurements and compare those measurements with ISTA's documentation for expected values.

Remember, when measuring O2 sensors, the engine must be at operating temperature. Ignore anything before this point.

Post voltage values for each lambda sensor (graph would be better). Pre-cat O2's should be a steady voltage below 1V...while your post-cat O2's voltages should be wandering around to support fuel trim...so if the post-cat 02 voltage is steady state, I'd call that bad.

check in at this point.

Do I click "Delete Fault Memory" under the "Fault Memory" tab?

[M_Bimmer]

Originally Posted by 750iClown

Do I click "Delete Fault Memory" under the "Fault Memory" tab?

Yes.

[750iClown]

Originally Posted by M_Bimmer

Yes.

Question, you said...

while your post-cat O2's voltages should be wandering around to support fuel trim...so if the post-cat 02 voltage is steady state, I'd call that bad.

Why do you say that would be bad? Wouldn't that indicate a bad post-cat O2 sensor if the voltage is not wandering and indicate a simple replacement of that sensor is needed?

[M_Bimmer]

Originally Posted by 750iClown

Question, you said...

while your post-cat O2's voltages should be wandering around to support fuel trim...so if the post-cat 02 voltage is steady state, I'd call that bad.

Why do you say that would be bad? Wouldn't that indicate a bad post-cat O2 sensor if the voltage is not wandering and indicate a simple replacement of that sensor is needed?

02


I should have been clearer. If you post-CAT Lambda sensor produces a steady state voltage, it could mean that the sensor is bad...and would set a fuel trim error.

[750iClown]

Originally Posted by M_Bimmer

02


I should have been clearer. If you post-CAT Lambda sensor produces a steady state voltage, it could mean that the sensor is bad...and would set a fuel trim error.

Here are the post-deletion faults? Next steps?

https://photos.google.com/photo/AF1Q...O_-8pglix1CJmY

https://photos.google.com/photo/AF1Q...H2UIL5DyQ2VB6y

[750iClown]

Originally Posted by M_Bimmer

02


I should have been clearer. If you post-CAT Lambda sensor produces a steady state voltage, it could mean that the sensor is bad...and would set a fuel trim error.

After disconnecting from the vehicle, I am in the house attempting to review the 4 remaining faults, but the operation no longer has them. Do I have to be connected to the vehicle to see them? Why did they disappear? Did I prematurely disconnect the interface cord?

[M_Bimmer]

Originally Posted by 750iClown

Here are the post-deletion faults? Next steps?

https://photos.google.com/photo/AF1Q...O_-8pglix1CJmY

https://photos.google.com/photo/AF1Q...H2UIL5DyQ2VB6y

Sorry, not able to get to these photos...requires a Google Account, which I do not have.

[750iClown]

Originally Posted by M_Bimmer

Sorry, not able to get to these photos...requires a Google Account, which I do not have.

I will get them up, but in the meantime, I am confused. How do I carry out this step? Do I have to have the car hooked up to my PC w ISTA? Do I need to start the car and look at the values for the O2 sensor while it's running? I need more help w this piece:

3. In service measurement = while running the engine, make measurements and compare those measurements with ISTA's documentation for expected values.

[M_Bimmer]

Originally Posted by 750iClown

Do I have to have the car hooked up to my PC w ISTA?

Yes

Originally Posted by 750iClown

Do I need to start the car and look at the values for the O2 sensor while it's running?

Yes

[750iClown]

Originally Posted by M_Bimmer

Yes



Yes

I think this shows how to do it

https://youtu.be/nCBWge_w-eQ?si=SevuNbCrjFx4tN__

[750iClown]

Originally Posted by M_Bimmer

Yes



Yes

If you can give me a step by step instruction on how to get the measurements from my vehicle please do tell. Here are a couple screen grabs from ISTA showing the ideal measurements of the post cat O2 sensor. I just need to know how to set up ISTA to show me my O2 sensor readings while the car is running and hooked up to ISTA.

[M_Bimmer]

Originally Posted by 750iClown

If you can give me a step by step instruction on how to get the measurements from my vehicle please do tell. Here are a couple screen grabs from ISTA showing the ideal measurements of the post cat O2 sensor. I just need to know how to set up ISTA to show me my O2 sensor readings while the car is running and hooked up to ISTA.

I'll have to hook up ISTA and try and get you a screen grab....there should be a "measurement" option....but you need to collect the real-time data from each O2 sensor while the vehicle is running, and after it's reached temperature.

My ISTA+ is an older version, so mine screen grabs may not be exactly like yours.