o2 sensor problem or more?

[Kyle2k]

So - I did a header install about a week ago and I got around to doing some data logging for a tune. Bank 1 was running +14-18 and Bank 2 was all 0's for fuel trims.

For clarification I am running the old CF 2 piece Haltech intake and it has like 102+mm MAF sensor diameter area.

Is this just a sensor issue? Another idea that has been thrown around is an exhaust leak?

EDIT: Rear o2 sensors are removed and I have no FRONT o2 sensor DTCs.

[04GOAT-11SS]

Exhaust leaks would be a good place to start looking. An O2 sensor generates a voltage signal based on the difference in oxygen content in the air in the exhaust and the air just outside the exhaust. The less of a difference you have, the leaner the computer thinks it's running. An exhaust leak in the right spot would put exhaust on the outside of the sensor, causing it to see very little difference. Thus tricking the computer into thinking it's running lean and it will try to compensate by adding fuel. Which will actually cause it to run rich.

An issue with the air intake or MAF should in theory cause an issue in both banks not just the one.

[Kyle2k]

I guess I'm just confused because the fuel trims on the one bank will NOT fluctuate from zero but at the same time I have no o2 DTCs so I have no clue if the sensor could also be fried/etc

[The Stig]

Any codes being thrown?

[thahemp]

Originally Posted by Kyle2k

So - I did a header install about a week ago and I got around to doing some data logging for a tune. Bank 1 was running +14-18 and Bank 2 was all 0's for fuel trims.

For clarification I am running the old CF 2 piece Haltech intake and it has like 102+mm MAF sensor diameter area.

Is this just a sensor issue? Another idea that has been thrown around is an exhaust leak?

EDIT: Rear o2 sensors are removed and I have no FRONT o2 sensor DTCs.

I just logged mine. It runs between +1 and 0 on both banks stft and ltft. +18 seems like quite a bit of fuel being added for just headers. I have an intake and PTB. The intake (Fastlane Pipeline) supposedly runs lean according to Jannetty.

Does bank 2 just stick at 0? Or does it bounce around between 0 and +1?

Exhaust leak is a good place to start... like was said already. That's what I would be hoping for!

[thahemp]

Originally Posted by Kyle2k

I guess I'm just confused because the fuel trims on the one bank will NOT fluctuate from zero but at the same time I have no o2 DTCs so I have no clue if the sensor could also be fried/etc

Snuck in before me. Maybe it's just going to take a bit for the code to be thrown. I have waited on codes for lots of miles before that I knew were supposed to be there. Do you have a multimeter? Or anything to monitor the voltage output from the bank 2 O2 sensor? I think it's supposed to fluctuate between 450 and 800mV as the computer trims things up.

[Kyle2k]

Originally Posted by thahemp

I just logged mine. It runs between +1 and 0 on both banks stft and ltft. +18 seems like quite a bit of fuel being added for just headers. I have an intake and PTB. The intake (Fastlane Pipeline) supposedly runs lean according to Jannetty.

Does bank 2 just stick at 0? Or does it bounce around between 0 and +1?

Exhaust leak is a good place to start... like was said already. That's what I would be hoping for!

Yeah, I was explicitly told this intake would cause +LTFTs as for the LTFTs on bank 2 I was told they are stuck at 0

Originally Posted by The Stig

Any codes being thrown?

P0036 and P0056 - I will update the thread with more as they come.

Originally Posted by thahemp

Snuck in before me. Maybe it's just going to take a bit for the code to be thrown. I have waited on codes for lots of miles before that I knew were supposed to be there. Do you have a multimeter? Or anything to monitor the voltage output from the bank 2 O2 sensor? I think it's supposed to fluctuate between 450 and 800mV as the computer trims things up.

I don't have a multimeter or anything to check voltage/etc. I will include some extra information that may or may not be helpful though. After I found out I went and did a fuse pull then started the car up and started logging. While idle - both banks had LTFT's at 15% then i went and drove around. After 5 minutes of driving Bank 2 settled at -1% and bank 1 was around the 15% still.

[thahemp]

Yep. Weird. Can you log O2 voltage? I can't remember if it is my sct or bluetooth module that shows the raw sensor voltages.

Just try loosening the headers and retightening them. It took me a bunch of tries to get everything happy at the manifold/midpipe flange when i did HF cats. It was a PITA to get it to seal.

[Kyle2k]

Originally Posted by thahemp

Yep. Weird. Can you log O2 voltage? I can't remember if it is my sct or bluetooth module that shows the raw sensor voltages.

Just try loosening the headers and retightening them. It took me a bunch of tries to get everything happy at the manifold/midpipe flange when i did HF cats. It was a PITA to get it to seal.

I looked it up and it seems I can do o2 voltage - I will check it out!

On another note - my STFTs do fluctuate. Does that not take o2 sensor readings into consideration? It literally is JUST my Bank 2 LTFTs that are stuck at 0

[Kyle2k]

o2 sensor voltages



I have some updates - did a very quick log of o2 sensor voltage and got some more trouble codes.

P0140, P0141, P0160, P0161, and finally P0154

It definitely seems to be the passenger side cylinder bank
http://www.obd-codes.com/p0154

It is weird though - it's like bank 2 is going into closed loop while bank 1 isn't? but the range for bank 2 (0.45 - 0.58V) seems too narrow based on the above information?

I will try get another log in the middle of the day and at a better operating temp.

[thahemp]

I haven't looked those codes up, but that is an interesting graph. The one fluctuating rapidly looks like it should i think. The stft should bounce from lean to rich repeatedly. That's how they find stoich.

Check that bank 1 header!

[Kyle2k]

Originally Posted by thahemp

I haven't looked those codes up, but that is an interesting graph. The one fluctuating rapidly looks like it should i think. The stft should bounce from lean to rich repeatedly. That's how they find stoich.

Check that bank 1 header!

Now that you say that- I agree...hmmm

[PQ]

This stuff has always been confusing as hell to me. I wish I knew more about how the system worked and what this all means.

It would have to be a decent size leak I'd think. I've had leaks that never messed with the fuel trims and sensors. I've also had them that did.

[thahemp]

Originally Posted by PQ

This stuff has always been confusing as hell to me. I wish I knew more about how the system worked and what this all means.

It would have to be a decent size leak I'd think. I've had leaks that never messed with the fuel trims and sensors. I've also had them that did.

Yep. It could be a leak or sensor. Basically the ecm adds fuel until the front O2 reads rich, then backs it off until it reads lean, then repeats. That's how it centers on 14.7. That +14 stft is the ecm adding 14% more fuel than the fuel map wants.... and it's still switching too slow.