2gGSX
15+ Year Contributor
- 1,956
- 30
- Feb 15, 2004
-
St. Louis,
Missouri
Cliff's notes: is it possible for a wideband to be reading too rich?
So, while my old turbo was in the process of dying and spewing out black smoke, I at one point noticed some coming out of my flex section. With that being said, the place I took my car to to get the bung welded on for my wideband decided to put it in BEHIND the flex section due to concern for exhaust temperatures being too hot.
Now, at idle, my wideband is reading 17:1-18:1. With ANY throttle and during closed loop operation it will settle around to oscillating 14.7 like normal.
At WOT, however, it seems to be reading more rich than normal. My estimated A/F Ratio and the wideband match up very closely. At WOT after reaching full boost however, the wideband starts to read consistently more rich than my estimated A/F Ratio.
What could be causing the wideband to be reading so rich? The exhaust leak is small enough to where it's not sucking air in at anything other than idle, and I don't know of any condition where the wideband sucks in extra fuel from exhaust leaks.
For the record, this is a PLX-M250. Power is tapped from the cigarette lighter (green/black wire), and the ground is off of the vertical bracket for the ECU (a chassis ground, I think). My airflow is reading correctly (just look at BoostEst vs. GM3Bar). Fuel trims are within 4% of each other. Both pulls were made at 100% throttle albeit not logged (I check it before startup fairly often).
In the first log (run11112007-1 3rd gear pull 1.dat) I was aiming for an AFR of 10.5:1. The estimated A/F ratio is very close to this, but the wideband is rich off the scale.
In the second log, I tried leaning it out to 11.3:1. Surely enough, the estimated A/F ratio looked like it was heading the right way, but then the car started knocking. The PLX also hits rock bottom just before I lifted as well. Something's messed up with the logs and you can't see the fuel/timing panels. For the record, 6000-8000 is at -18%, 4000-6000 is at -16%, and the rest is scaled back to zero so it's not a sudden jump. Timing is the same as in the first log, as is global fuel.
So, while my old turbo was in the process of dying and spewing out black smoke, I at one point noticed some coming out of my flex section. With that being said, the place I took my car to to get the bung welded on for my wideband decided to put it in BEHIND the flex section due to concern for exhaust temperatures being too hot.
Now, at idle, my wideband is reading 17:1-18:1. With ANY throttle and during closed loop operation it will settle around to oscillating 14.7 like normal.
At WOT, however, it seems to be reading more rich than normal. My estimated A/F Ratio and the wideband match up very closely. At WOT after reaching full boost however, the wideband starts to read consistently more rich than my estimated A/F Ratio.
What could be causing the wideband to be reading so rich? The exhaust leak is small enough to where it's not sucking air in at anything other than idle, and I don't know of any condition where the wideband sucks in extra fuel from exhaust leaks.
For the record, this is a PLX-M250. Power is tapped from the cigarette lighter (green/black wire), and the ground is off of the vertical bracket for the ECU (a chassis ground, I think). My airflow is reading correctly (just look at BoostEst vs. GM3Bar). Fuel trims are within 4% of each other. Both pulls were made at 100% throttle albeit not logged (I check it before startup fairly often).
In the first log (run11112007-1 3rd gear pull 1.dat) I was aiming for an AFR of 10.5:1. The estimated A/F ratio is very close to this, but the wideband is rich off the scale.
In the second log, I tried leaning it out to 11.3:1. Surely enough, the estimated A/F ratio looked like it was heading the right way, but then the car started knocking. The PLX also hits rock bottom just before I lifted as well. Something's messed up with the logs and you can't see the fuel/timing panels. For the record, 6000-8000 is at -18%, 4000-6000 is at -16%, and the rest is scaled back to zero so it's not a sudden jump. Timing is the same as in the first log, as is global fuel.