Running rich?

[99BB3500]

If one bank O2 is acting funny but the other looks normal, an easy check is to swap them and see if the problem switches to the other bank.

What does the other side look like?

That’s both upstream sensors. Bank 1 and bank 2.

 

[99BB3500]

Visually speaking they’re probably the original ones and coated in undercoating

 

[stutaeng]

Oh, I see now...

I've got a rich condition on my project Silverado right now. I did a V6 to V8 swap on a LM7 tune, but the injectors are higher flowrate (engine is an L59 with flex fuel.)

Anyway, I'm pretty sure it's the injectors on my case, just haven't had a chance to change them out. I'm about 10-11% rich on the LTFT, exactly on both banks. Codes are set for both banks being rich, but truck drives just fine. I believe the ECU can adjust up to +/-25% to compensate.

I just went to look and my upstream 02 sensors with my cheap handheld scanner and they still show that sine wave I was mentioning... IIRC, those 02 sensors have a common ground in the harness. I would look at the ground on them. Otherwise looks like they may be bad. But I'm suspicious because they are reading almost indentical to one another...

I hope this helps.

 

[99BB3500]

If it’s supposed to alternate voltage that fast then it’s probably the sensors. I had a 05 Sierra with an LM7 that ran WAAAAY better than this 454