Warming up in open loop stft's are equal, when it switches to closed loop, b2 is +6 over b1. Haven't made any tune changes. The wideband is in b2 and is reading 14.7 or so at idle. I recently switched to HPT version 3 and am having a little trouble getting used to the changes. What would make a diff in bank to bank? LTFT's are off. SD tuned
Thanks for any ideas.

 

Differences in fuel trims between the banks is typically caused by an exhaust leak but there can be other contributors too.
Off the top of my head:
* cylinder misfire
* faulty O2 sensor
* faulty fuel injector

 

Guess I will pull the plugs and do a check. My o2 sensors are switching and at about the same mv.
Thanks

 

Flow-matched injectors? If not, you can see 5-10% off bank-to-bank.

If one O2 switches slower, that could cause it too. Flip the O2s and see what happens.

I try to read off Bank 2 with my wideband since it runs a little leaner with the way the plastic intakes deliver the airflow.

 

Injectors are not flow matched. FAST 60#. I have the wideband in B2. Blower intake, not the stock one. This problem just started. STFT's have been the same bank to bank for a long time. Plugs all looked the same so I shouldn't have a lean or rich cylinder. I will switch the o2's---its a knuckle ripping job on one side. The o2's are fairly new Denso's. I just retuned the Primary VE and its better, but still not right.

 

That would be the case if he saw something like 10%+ difference between the two.

6%? I wouldn't worry about it and like Jake said could be lots of normal contributors to this that aren't necessarily issues.

 

This may be stupid but I feel I should just get it out there. B1 and B2 switch back and forth from rich to lean. They're supposed too.
If you knew that, forget I said anything.

 

I think the issue is if you watch the graph in the scanner and they are always 5-10% apart or less then you're okay. If they are always 10% apart or more, you have an issue. But yes, they switch back and forth due to the narrowbands switching.

 

Exactly, The lines on the scanner are about 6% apart. Normally they are right together. At wot the o2's are both reading at 900mv +, so no worries at wot. I just want to get the part throttle fixed. I'm swapping the 02's today and see what that does. Dam electronic sensors **$%&.

 

At WOT they are useless, so I wouldn't worry about what they read there.

Like we said before, we don't think this is an issue. But you're welcome to throw money at it if it makes you feel better, just don't expect wildly different results. If an o2 sensor was indeed bad, it would be a helluva lot more difference than 6.

 

I did swap the Denso sensors back to the stock ones. Not much change in stft's. The stock GM ones do switch better than the Denso's. Maybe a dirty injector or I'm just too picky. I checked the tune because I am going to add a 75 shot to cool the IAT's on the maggie so it will not pull so much timing at wot. When I checked, the primary ve was a bit lean at idle and the boost ve was about 12% rich. When I tuned it a few months ago, everything was within 1-2%. Its 2 bar sd, so maybe the weather?? I just wanted to get the non nitrous tune correct before I tuned for the shot. Thanks for the reply's.