Closed loop during boost? (wideband)

HiProfile · Post by **HiProfile** » Tue Nov 11, 2008 2:58 pm

I was wondering, for closed-loop eCtune uses the target AFR table you can adjust, right? If so, if I tune the map in open-loop mode to get the AFR's spot-on (on both the raw & target maps), then go with closed-loop with the wideband - it should work for boost too, right? I know some people will say \"if its tuned, why mess with boost AFR's?\", but this would work as a safety net, in addition to saving some gasoline. I know there's already lean protection, but more is usually better. Is it a waste of time or what?

Post by **Gaskleppie** » Wed Nov 12, 2008 3:23 am

I think that the closed loop adjustments are too rough to get a stable AF... If you want to save gas, just make a 2nd map with a switch to set a lot leaner values into the lower boost columns. If you want to race, just switch over and you have aggressive ign and fuel maps!

RoadXY · Post by **RoadXY** » Wed Nov 12, 2008 9:22 am

Target AFR table's are for tuning, not for closed loop, right?

Post by **Gaskleppie** » Wed Nov 12, 2008 4:32 pm

Target AFR table's are for tuning, not for closed loop, right?

Your absolutely right about that!

Post by **Synoptic** » Wed Nov 12, 2008 9:25 pm

I would not rely on a 55$ sensor for closed loop during boost. Just imagine...

Orthello · Post by **Orthello** » Thu Nov 13, 2008 5:03 am

Gaskleppie wrote:
Target AFR table's are for tuning, not for closed loop, right?
Your absolutely right about that!

And apart from that, Closed Loop corrections use 14.7 as a target, while you want 13~12 as target during boost. If the AFR target table was used by the ECU, the ECU would be abble to tune itself. If AFR measuments were reliable enough, ECU would already be self tuning. But just very few (none??) ECU's are able to tune itself.

HiProfile · Post by **HiProfile** » Thu Nov 13, 2008 1:26 pm

Well in my limited experience, changes to the target afr table when closed loop was on & wideband used, it seemed to actually target that AFR value, not 14.7. I know the VX/HX actually do have a lean-burn mode where it can cruise along at nearly 20:1, although the engine was also designed around that. My point is they chose a wideband because of that. FYI many OEM ecu's have short & long-term corrections, although they are generally MAF-based. BMW's for instance are notorious for making big corrections to target 14.7 when you use a piggy-back to modify fuel values. I guess all I really wanted to clairify was if the target AFR table was indeed used to target a certain AFR when using a wideband. I can't really test this now, since my coupe is parked for the time being, and technically trying it on my beater would be against the rules I think...

borat · Post by **borat** » Thu Nov 13, 2008 7:51 pm

Closed loop is only useful during steady-state conditions. The only time you'd be steady-state in boost would be if you're going up a really steep hill, or cruising at 100+ mph. Are target AFRs even stored as part of the bin that the ECU runs off of? I always thought they were part of the calibration file for whatever tuning software you were using, and therefore only used along with datalogging. If not, there's no reason a target lambda table couldn't be used full-time. It would be useless when accelerating, unless your ECU and wideband can react fast enough to modify fuel values as the engine runs through the table. Automatic fuel tuning is absolutely possible, as long as the ECU can save its changes. Since ours can't directly, we need to rely on our tuning programs for those features.

elevation · Post by **elevation** » Thu Nov 13, 2008 8:58 pm

Dosent the ecu switch to openloop(if your in closedloop) after a certin tps voltage? In uberdata the last thing people were working on was openloop via load. This would be a cool option that may have been forgotten about. Since ectune uses p72 code maybe the old uber file would help beneficial? I think I have it 2 laptops ago.

borat · Post by **borat** » Thu Nov 13, 2008 10:23 pm

Pretty sure the open-loop / closed-loop switchover is already fully configurable.

Post by **calvin** » Thu Nov 13, 2008 10:32 pm

borat wrote:Pretty sure the open-loop / closed-loop switchover is already fully configurable.

correct

Post by **Gaskleppie** » Fri Nov 14, 2008 3:19 am

Dosent the ecu switch to openloop(if your in closedloop) after a certin tps voltage?

Its load dependent. You can set a vacuum value to switch over. Some cars have very poor vacuum and because of that it jumps out of closed loop at the slightest touch of the gas pedal. Setting this vacuum value higher gives the customer more fuel efficiency.

elevation · Post by **elevation** » Fri Nov 14, 2008 11:57 am

Gaskleppie wrote:
Dosent the ecu switch to openloop(if your in closedloop) after a certin tps voltage?
Its load dependent. You can set a vacuum value to switch over. Some cars have very poor vacuum and because of that it jumps out of closed loop at the slightest touch of the gas pedal. Setting this vacuum value higher gives the customer more fuel efficiency.

I'm @ 6500ft so thats something I have to look into. Thanks