Bank 2, too lean

[Cubieman]

Posted in the dumb question thread but wanted to see if I could get a few more ideas.

Got my very first "service engine soon" light today after 5 years, it was a P0174 (bank 2 too lean). The code popped up on the interstate comming back from a track day.

I had a cheap OBD Bluetooth scanner/App and cleared the code while driving and it never came back driving over an hour home on the interstate and through town.

I have a CSL tune/MAP sensor, when the CSL airbox was put on 3 years back all new boots were used with OEM clamps, OEM CSL hoses were used, I even put new air rail orings in, new pre-cat O2 sensors were installed in the same time frame along with having my injectors sent out to RC for cleaning.

With the CSL tune in mind what else should I be checking for besides an air leak? I have a WB O2 sensor in bank 2, so I'll have to hook up testo and check that out sooner than later.

[repoman89]

This is expected and normal with the HJS Supersprint catalysts. Many people here have posted with the same issue, always steady RPM highway driving. Delete the cat efficiency codes and don’t worry about it. The car is just telling you the truth — your catalysts aren’t working as well as the ones that come on the car from the factory. They are race cats after all.

edit: mixed up my codes, never mind

[Cubieman]

This is expected and normal with the HJS Supersprint catalysts. Many people here have posted with the same issue, always steady RPM highway driving. Delete the cat efficiency codes and don’t worry about it. The car is just telling you the truth — your catalysts aren’t working as well as the ones that come on the car from the factory. They are race cats after all.

Ok, so this is not in reference to the pre-cat O2's? I figured it was, I believe I have my post cat O2's "deleted" but I'll have to double check.

I drove around town last night with my WB O2 and it seemed OK (hovering around 14.7), but yesterday was a track day and only my 2nd, so the engine saw different conditions than usual. However the first time I had it on the track this issue did not arise.

[repoman89]

Ok, so this is not in reference to the pre-cat O2's? I figured it was, I believe I have my post cat O2's "deleted" but I'll have to double check.

I drove around town last night with my WB O2 and it seemed OK (hovering around 14.7), but yesterday was a track day and only my 2nd, so the engine saw different conditions than usual. However the first time I had it on the track this issue did not arise.

Ugh my bad! Ignore me. Got my codes mixed up, I was thinking P0420.

What do your adaptations/fuel trims look like?

[eacmen]

Ok, so this is not in reference to the pre-cat O2's? I figured it was, I believe I have my post cat O2's "deleted" but I'll have to double check.

I drove around town last night with my WB O2 and it seemed OK (hovering around 14.7), but yesterday was a track day and only my 2nd, so the engine saw different conditions than usual. However the first time I had it on the track this issue did not arise.

Do you log min/max on your wideband while on track?

[Cubieman]

Do you log min/max on your wideband while on track?

I did not, I use a laptop/testo to get that info and never having any real issues with the car before I haven't had a reason to log.
Next track day may be on the 20th so I'll be logging data for sure then.

It may be tune related, I don't know of course, it's interesting it didn't show up on track.

We left the track, I topped off the tank (just over a Qtr.), hit the interstate and within 10mi of driving the SES came on, was cleared and didn't come back.

[sapote]

Post a warm idle log with LTFT and STFT. I don't know if the DME can output calculated air mass rate as you have MAP instead of MAF now.

[Cubieman]

Post a warm idle log with LTFT and STFT. I don't know if the DME can output calculated air mass rate as you have MAP instead of MAF now.

Using Testo last night I could not help but notice that I could live data from the "MAF" sensor, currently I have my IAT plugged into the MAF sensor connector with an adapter so maybe it's reading the IAT, not sure.

I'll use the ECUworx tool to look at Long and Short term fuel trims and do some logging when I get a chance.

Having a lean condition isn't something I want...not so great.

[Cubieman]

FWIW here's a snapshot of the fuel trims etc. after some somewhat spirited driving around town last night for about 45min.

I'll post a log when I have some more time, thanks for the help!

[sapote]

FWIW here's a snapshot of the fuel trims etc. after some somewhat spirited driving around town last night for about 45min.

The ECUWORx tool shows STFT2=-0.03 and LTFT2=0.91
These number seem to be so small and should not cause a lean code. If ECUworx has STFT in ms of pulse width then without knowing the table or calculated injector pulse width then giving STFT in ms makes no sense as we have no idea what percentage 0.03ms is from the calculated pulse width.
And if both STFT and LTFT are in percentage, then these value cannot cause a lean code as they are too small.

[S54B32]

The ECUWORx tool shows STFT2=-0.03 and LTFT2=0.91
These number seem to be so small and should not cause a lean code. If ECUworx has STFT in ms of pulse width then without knowing the table or calculated injector pulse width then giving STFT in ms makes no sense as we have no idea what percentage 0.03ms is from the calculated pulse width.
And if both STFT and LTFT are in percentage, then these value cannot cause a lean code as they are too small.

I have to disagree, near 10% less fuel can indeed cause a lean condition. Especially with a (canned?) tune, I suggest to contact your tuner (HTE), because with 8 and 9% LTFT your map has rich spots where the ECU adapts the fuel down and multiplicate this trim also on WOT events where o2 correction is not active. In my opinion 2-3% fuel correction is okay, but not near 10% on a narrowband dme controlled engine!

btw do you have your WBO2 on bank one or bank two? Or do you have dual channel WBO2? Sometimes a injectors starts clogging and cause lean conditions on one bank, but as you the both fuel trims relative bad, I don’t think this is the case.

[Cubieman]

I have to disagree, near 10% less fuel can indeed cause a lean condition. Especially with a (canned?) tune, I suggest to contact your tuner (HTE), because with 8 and 9% LTFT your map has rich spots where the ECU adapts the fuel down and multiplicate this trim also on WOT events where o2 correction is not active. In my opinion 2-3% fuel correction is okay, but not near 10% on a narrowband dme controlled engine!

btw do you have your WBO2 on bank one or bank two? Or do you have dual channel WBO2? Sometimes a injectors starts clogging and cause lean conditions on one bank, but as you the both fuel trims relative bad, I don’t think this is the case.

The wideband is only on bank 2, I'll have to reach out to HTE and see what he thinks after I send a few logs as this car was dyno tuned with all the current modifications.

[eacmen]

I would recommend getting a wideband gauge with min/max feature to take the guess work out of it.

[S54B32]

If you have all present, log the wideband over serial port and load/rpm etc with testo, buy a megalog viewer HD license and you quickly will find you rich spots in the map.

[ATB88]

My ltfts typically sit near 8-10 on each bank, have for years, and I have never gotten any sort of lean code/warning. Interesting.