Semi-Open Loop Vs Just Open Loop

[Delco]

Problem with semi open loop is that the banks almost always get fueled differently (+- a few %). Now while this might actually be correct, it might also be a reflection on the state of the sensors etc.

I guess best idea is hold the engine at say 70kpa and 4000rpm and change from open (equal fueling) to closed loop (bank dependent fueling) and see if the power changes.

Who wants to do that and report back any differences significant or otherwise?

Someone with a Dyno? Daniel?

You can vary the AFR by from 15.2 to 13.4 at part load with vary little change in power output on the dyno , fuel consumption changes heaps though.

What you find is its not bank related the variance in fueling but cylinder efficiency at different loads as speeds s the airflow changes in the manifold , not really a issue at part throttle or naturally aspirated but when blown I can detect a huge difference hence we tune to the leanest cylinder so as not to cause a breakage , when looking at a O2 you are just seeing a average of that bank.

Closed loop O2 cycling will also be different between 2 )2 sensors hence you can have a slightly different trims , the LTFT's are just trying to keep it in the aveage 14.63 area and overshoot and undershoot to do it , this can be by a different amount as well.

Personally tuned properly and maintained a car will always run better and more efficiently in open loop than in closed loop , the closed loop masks poor tuning and differences between engines and environments

[oztracktuning]

How technically do you tune to the leanest cylinder?

[ringram]

Cool thanks for the info dan.

Flyer maybe Dan uses something like this http://www.innovatemotorsports.com/products/st12.php

Perhaps he even flow tests injectors and arranges them to suit as well? Though Id guess its a moving target as the engine wears.

[BowlingSS]

[quote=ringram]
Flyer maybe Dan uses something like this http://www.innovatemotorsports.com/products/st12.php
quote]

I want one of those.

Bill

[Delco]

Cool thanks for the info dan.

Flyer maybe Dan uses something like this http://www.innovatemotorsports.com/products/st12.php

Perhaps he even flow tests injectors and arranges them to suit as well? Though Id guess its a moving target as the engine wears.

8 Exhaust thermocouple is the only way on high hp stuff , especially blown combos that have a big cylinder distribution problem , its different cyl's too depending on the type of blower and intake.

[BowlingSS]

8 Exhaust thermocouple is the only way on high hp stuff , especially blown combos that have a big cylinder distribution problem , its different cyl's too depending on the type of blower and intake.

[TAQuickness]

some how got to thinking about his topic late last night...

Another area semi-closed loop or full closed loop would be helpful is if you are utilizing the dual spark maps.