As most of you guys know I've been OLSD tuning for awhile.

Yesterday I decided to turn on Closed Loop and see how it looks. Even though in OL by AFR error is +- 4% my LTFT's have fallen into +0-5%. Now if I understand this correctly, when I enter PE it will pull the LTFT into my PE fueling equation, thus explaining why I am pig rich in PE now.

 

Open loop=no trimming, the only way to really get here is to turn the trims st and lt off and tune the VE via a wideband and afr correction
closed loop=trimming

Positive trims mean adding fuel because the pcm thinks its lean.
Why does it think its lean at wot? Look at B1 and B2 voltages tell me what you see.

 

There should be no trimming in PE.

 

Hopefully the resident sponsor from HPT will jump in and explain a reason for differences in B1 B2 voltages when in PE and consequent trimming. I think the reason is from one side being leaner but have no proof other than stock 02 voltages, I get 100mv difference but KY yours is 200mv Ive never seen it that big before.
The solution to your problem is to turn the ltft's off and itll go away; makes sure to reset trims after making air adjustments or messing with trimming.

 

B1 is a WB 02 simulating narrowband. This is the second WB unit I've had and they both have behaved this way.

Even before the WB, B2 has always run a tad leaner than B1 in my truck.

 

This is a bit strange. The 2 bar OS even has a BE table and trigger for OL which is set at 110KPA.

Surely its not CAT OT enrich?

 

I've been OLSD tuning WB for weeks now. Just turned CL back on.

 

If youve got trims going on you arent in open loop

 

I think he's aware of that considering he just stated he turned closed loop back on

 

I am aware of this. The point of this post. I had been OLSD tuning for weeks. I have now enabled CL STFT's and LTFT's. In OLSD I have gotten VE pretty darned close, commanded AFR% error within 3-4% and now when I turned CL back on it has driven my PE fueling very rich. In open loop I am within 2% of commanded. With closed loop enabled my PE is 9% rich. WHY? It appears it is bringing LTFT correction into PE which I don't understand.