6.0 lq4 stalls in parking Maneuvers

[verlon]

I have took builds where i didnt have a good startup map and tuned cl nb and then switched to ol wb. Has anyone used a high end combustion analyzer to confirm either cl nb or ol consumer grade wb are actually better than the other?

'better' is not correct word
NB and WB are equally precise if properly compensated. WB sensor uses ion pump over the same NB sensor core.
WB can be more convenient under one circumstances and NB under other.

I prefer NB and even OL NB in specific conditions.

[abc]

I prefer NB and even OL NB in specific conditions.

(what are the specific conditions?)

I don't know if this is the right time or place but can you elaborate based on your knowledge for me/us please?

Is it possible and/or even desired to have a NB calibrated to switch at some voltage other than stoich. in any scenario? (Describe scenario)

In your opinion is there a situation that a WB is a must have?

[verlon]

(what are the specific conditions?)

I don't know if this is the right time or place but can you elaborate based on your knowledge for me/us please?

In the low-rpm area, when engine speed drops below 500 rpm. It can be coasting or unstable idle.
I just need to determine tendency of VE, not exact numbers. WB is not fast enough in such cases because of very low exhaust flow and CL NB quickly saturates fuel trims.

Is it possible and/or even desired to have a NB calibrated to switch at some voltage other than stoich. in any scenario? (Describe scenario)

I think not. NB is linear only near stoich.

In your opinion is there a situation that a WB is a must have?

Hmmm... for me - no.
I've tuned SC LS7 with TVS2650 this summer using stock NB You just have to be very careful not to melt pistons, valves and catalyst. It is a good way to look at saturated rich NB voltage which depends on sensor temperature to detect a condition when you are going to get really hot.

[Alvin]

Yes it is. OL is a last resort. If NB bounding trend isn't correct then the attempt should be made to adjust PI settings. If control isn't achievable then resort to OL. A good spark map is critical.

CL is better in principle. It is actually a minority of cases where it can't be made to work, as large duration cams and radical intakes are in the minority of installations.

What is good advice for many applications?

I didn't say anything about putting it in OL. You can use both simultaneously. In fact I can't think of the last time I forced a car in OL to use a wideband. Yet I'm using widebands daily on all aspects of tuning.

To say you can get the VE table correct with just fuel trims is just not correct. The fuel trims especially in GEN 3's move to slow to do this. There are several areas like decel or very light load idle-3000 RPM that really need a faster responding wideband to find. Areas like this directly impact idle stability. When the engine runs though one of these zones at just even 10-15% too rich.. It will load the engine up and it's enough to cause a idle dip.

Bottom line.. It's entirely possible/likely to have pockets in the VE table very far off yet the fuel trims look very close.


I'll give you guys a hint on this..

In a particular cell.. If LTFT and STFT are averaging out to a +5% but the wideband is showing a -20% what should the correction be?

Now, having said that.. once the shape of the VE is in order.. I'll let the fuel trims have the final say in part throttle fueling. But trust me.. the more cam it has.. the more a wideband should also be referred to while tuning these in. Also, side note.. care needs to be taken not to average in data while in DFCO CFCO etc.

[SiriusC1024]

In a particular cell.. If LTFT and STFT are averaging out to a +5% but the wideband is showing a -20% what should the correction be?

The answer depends on the behavior of the narrowbands. If they are oscillating then I doubt there's much disagreement between the two. It's more likely that mode vs airflow needs tracked then the P and I terms adjusted to restore proper switching.

The only place I commonly see this scenario is when the throttle is shut off WOT. It's considered a transient. Neither the wideband nor narrowbands are getting accurate data here. The transient fueling tab, injector data, and dynamic airflow prediction gets that inline.

The VE table isn't meant for transients. This is easy to demonstrate. Make corrections based on the wideband during the transient. Now hit those cells with steady throttle. Big difference.

The wideband is useful for quickly getting VE shape. CL fuel trims do take a bit to respond. Still, it only takes about 6 revs to the VE table with the narrowbands and I'm done.

[Alvin]

What I'm pointing out.. is fuel trims will not move fast enough to see this pocket/hole whatever you want to call it. It doesn't have to be transient.

Because of that they are still reporting lean when engine is actually rich.

[RiggsStubbs]

Ok so last night I attempted dialing the VE table in more and that didn't seem to do much. so I tried messing with the BRAF and added some to both in gear and park/neutral. this did seem to help in most situation, but with quick throttle blips under full load it will still stall. What am I doing wrong?

[SiriusC1024]

Well in the first post you said you had VE dialed in, yet it's a stock VE table.

I'm pretty sure it's still wrong.

[RiggsStubbs]

You mean I messed up the stock one? I believe it hahaha maybe i was adjusting the wrong table? its been a few months since I touched this thing but I swore I made changes to it.