jpandes

I street-tuned my FD around a year or so ago using a TechEdge WB2.0 and a Datalogit. I tuned for 11.2-4 at WOT at +/-1 Bar(13.5-14.5 psi)
Click here for a complete mod list: http://www.cardomain.com/ride/336795/2

I have my WB installed full-time with a display mounted on the dash. I am now seeing much richer AFR's at WOT as low as 10.2(at different times and temps, still richer than I tuned for)

What could be the cause for the car to be running this rich? I plan to change the spark plugs and clean the intakes to see if that changes things. I am also seeing slightly higher knock peak readings.

I spoke to Sonny at RotaryExtreme about this, he said that is t could be a number of things...(bad plugs, wires, or a tired motor that is loosing compression). He saud that it is normal to re-tune each year as the motor wears. I sure as hell hope that my Pineapple-built street ported motor isn't going bad...

What are the signs of a WB O2 sensor going bad? Besides, just not getting a reading. I wish I could calibrate it.

Do you guys have any other ideas?

TIA,

John

twokrx7

iTrader: (1)

As my older wideband sensor started to age it read leaner. Cannot recall if this is normal, my memory is fading. Didn't know it until I purchased a new wideband for permanent install and what do you know, it read rich. After confirming the reading with a reference gas I would give credibility to the newer sensor if it's installed right with no ground reference issues. If you have one with a built-in display meter it helps to ensure the datalogging is at least consistent with the display and your entered values in the datalogit are correct for the meter.

Any reputable high end tuner shop should have a calibration gas that reads a known AFR. The local Porsche tuner in Houston had a can of this reference gas that he used to verify calibration of their $300 wideband sensors. It's not cheap but it is available. When tuning $100k and up cars they pay to be spot on (if I were tuning a Motec for a new 2004 Ferrari motor I would want to know the wb is spot on).

You can always compare with other widebands.

Most widebands have a test or default output for certain conditions which indicate if the sensor or circuit is working, have you verified this.

Air temps can have an effect if your fuel vs. air temp has not be rescaled to provide consistent AFRs between warm and cold IATs ... stock PFC scaling is not linear but I don't recall it being that far off for small changes in IAT.