A/F Ratio Opinion Anyone?

[12secSS]

Usually when you close the throttle quickly you get a short richness before it goes lean. Normal as the MAP decreases rapidly but there is still fuel in the manifold that needs to go somewhere.
No matter what I set all the DFCO settings to (and I tried them all) I still have the Fuel Trim Enable bit going off during deceleration, even light deceleration which makes me think DFCO is still enabled. Plus the AFR goes quite lean as it should when DFCO enables.

EC

HA! And I thought I was crazy when I was tuning an LS2 and it did just that. I will have to research more into this and try and clear it somehow.

[djt81185]

When you go closed loop do you have lean areas right after you let off after accelerating? have tried six ways from Sunday to disable DFCO & haven't found a solution yet. There's trouble in paradise...

Hey

I'm tuning my LSJ I4 and I'm having the same exact problems. I'm trying to SD tune but the first 2 map cells 15 and 21 kPa just go stupid lean even with all dfco values turned off. Also if I post my logs and tunes can u guys help me get this SD nailed down?

Thanks,

Dan

[WS6Fury]

Usually when you close the throttle quickly you get a short richness before it goes lean. Normal as the MAP decreases rapidly but there is still fuel in the manifold that needs to go somewhere.
No matter what I set all the DFCO settings to (and I tried them all) I still have the Fuel Trim Enable bit going off during deceleration, even light deceleration which makes me think DFCO is still enabled. Plus the AFR goes quite lean as it should when DFCO enables.

EC

I got the same exact problem, all of DFCO is completely disabled, but on hard decel from all these runs, the low MAP, high RPm to low RPm areas of the VE table are peaks and valleys. I get one rich area, and one very lean area, and it smooths up to regular running MAP areas.

Any thoughts on what you've seen??? I'm just wondering if I should just flatten it out and call it a day even though it may or may not be "accurate".

[TTZ06]

I am using an AEM WB sensor.
Mark

What settings did you use on your aem wb? Mine was off on using the included eio config. I am at .6 and 10 and it seems close at 14.7 but don't know what's gonna happen at each end of the spectrum.

[EC_Tune]

There is one other setting that comes on at low MAP pressures: Deep Decel Fuel Cutoff. <-- that's where you see the injectors go to .3 or something like that. Fuel is Off.

Deep Decel settings are in the Dynamic Airflow tab of the V8 Non-GenIV engines. Not sure about 4/5/6 cyl cals though.

[barkingspud]

What settings did you use on your aem wb? Mine was off on using the included eio config. I am at .6 and 10 and it seems close at 14.7 but don't know what's gonna happen at each end of the spectrum.

Not sure I understand the question.....There are only two calibration settings on the AEM, one for standard A/F and one for display in Lambda.....

[TTZ06]

Not sure I understand the question.....There are only two calibration settings on the AEM, one for standard A/F and one for display in Lambda.....

I'm referring to my AEM WB gauge that I hooked up to HPT Enhanced I/O.

There is a default I/O to select in HPT for AEM/WB.

If I run that default config, the gauge reads 14.7, HTP logs 15.7

[barkingspud]

I'm referring to my AEM WB gauge that I hooked up to HPT Enhanced I/O.

There is a default I/O to select in HPT for AEM/WB.

If I run that default config, the gauge reads 14.7, HTP logs 15.7

So, it logs the wrong AFR in the WB AFR histogram? Interesting. I don't have that problem....

[WS6Fury]

There is one other setting that comes on at low MAP pressures: Deep Decel Fuel Cutoff. <-- that's where you see the injectors go to .3 or something like that. Fuel is Off.

Deep Decel settings are in the Dynamic Airflow tab of the V8 Non-GenIV engines. Not sure about 4/5/6 cyl cals though.

Found it, mine is set to 16kpa. On the scan log, it seems to affect the 15 and 20kpa rows. So I'm not sure if this has a small affect on surrounding cells or not. So should I just bring this down to 0 for now so I can get a flat VE table at low map deep decel? Or not too safe??

[TTZ06]

So, it logs the wrong AFR in the WB AFR histogram? Interesting. I don't have that problem....

Yes, it is wrong. I setup a custom device and got it to match using manual settings until I found the right ones. I thought maybe I had a weak ground.

[EC_Tune]

WS6, yep you can. No need to go below 10 as that's the bottom end of the MAP sensor anyway.