Oxygen Sensor vs PE (Power Enrichment) for a TT 5.7 chip

[Steve Wood]

I asked Eric how it worked...this is his answer

Hi Steve,
Once PE mode is active, input from the O2 sensor is disabled, and the INT (short term fuel trim) is forced to 128.

However, the BLM is not forced to 128 until around 200gr/sec (about 10psi boost). So if the O2 sensor was bad, which caused the last BLM cell to be jacked up (the 12th cell in that chip), that cell would still be used up to around 10psi.

After 200gr/sec, the BLM is forced to whatever value someone put into the WOT fuel param (#1), which would be 128 if no one changed it. The O2 sensor has no effect on anything at that point.
 

[Scoobum]

So at 10 PSI boost and up...fueling is dictated by whatever number I put into parameter 1 (high gear fuel)...or default if I don't adjust it. The 02 sensor is merely reading the exhaust at this point?

Which is cell 12? I gotta fire up my laptop from the car with PL on it.

[Steve Wood]

Bottom right on the matrix

[Scoobum]

Looked at one of my runs from a couple of weeks back. PE starts at 72 gs/sec...2625 RPM's sitting on the footbrake. 02 sensor is merely along for the ride.

Steve...thanks for contacting Eric...this is cool stuff.

[phil_long]

this is very informative!! So a bad o2 sensor would just give false readings, but not affect the actual performance...

[Steve Wood]

not past 10 psi of boost. 

As I have told you, I don't think it is the sensor that is causing the problems but I want to know I am looking at the correct numbers.  For $15-$20, I figure it is minimal expense to know that the declining O2s are real.

I still want to see a different ecm, exhaust leak test, voltage at wot throttle on repeated runs, and the other things we have talked about.

Did you mention how much timing retard you are seeing?

[motorhead]

It is called open loop when the O2 sensor is not referenced; closed loop is when it is referenced.

http://www.enginebasics.com/EFI%20Tuning/Closed%20Loop%20o2.html

[phil_long]

Never mentioned the KR. And I plan to tackle everything we've discussed. Gonna be pretty busy with boy scout crap this week all the way through sunday. The KR sometimes is 0, and other times 2.1 or so. it varied. Motor mount is to be installed next as well. Slow strolling through this thing. Appreciate the help

[good2win22]

It is called open loop when the O2 sensor is not referenced; closed loop is when it is referenced.

http://www.enginebasics.com/EFI%20Tuning/Closed%20Loop%20o2.html

That link has a lot of good info!  Thanks for sharing