Semi-Open Loop Vs Just Open Loop

[BowlingSS]

Has anyone compared running in semi-open loop (AFR at 14.63) vs just running open loop (AFR somthing else). I am running MAFLess in open loop using COS3. I just setup the AFR for most of the table to go into Semi-Open Loop. I am monitoring the STFT's and was wondering what to do with these numbers. I have been in open loop soo long that I have not logged trims in months. What does it buy me running in semi-open loop?

Bill
:thankyou2:

[TAQuickness]

Has anyone compared running in semi-open loop (AFR at 14.63) vs just running open loop (AFR somthing else). I am running MAFLess in open loop using COS3. I just setup the AFR for most of the table to go into Semi-Open Loop. I am monitoring the STFT's and was wondering what to do with these numbers. I have been in open loop soo long that I have not logged trims in months. What does it buy me running in semi-open loop?

Bill
:thankyou2:

closing the loop allows the PCM to compensate for inaccuracies in fueling.

I recently enabled closed loop for the hell of it. I was quite pleased with the LTFT results at FTC19, but otherwise my LTFT's were so squirley I went back with OL.

I'm contemplating aquiring a second LC-1 and configuring the pair to drive NB signals to the PCM and WB signals to Flashscan. When I get to this, I'll do back to back comparo's of NB LTFT's and WB LTFT's.

[GMPX]

If you have got your VE spot on in full open loop then switching back to semi open loop will just allow the PCM to hover around the 14.63 mark as it normally would, when it does this you can see the STFT's adjust back and forward, the difference is if there is a trend to rich or lean with the STFT there is no 'long term' compensation for it to pull things into line, but if the VE is mapped spot on then there is also no need for long term trims.

Cheers,
Ross

[BowlingSS]

My car seems to run better when not in the semi-open mode. I like checking my BENS all the time anyway.
:thankyou2:
Bill

[BLK02WS6]

If you tuned it spot-on with a wideband and then it runs worse when placed in semi-open loop, that indicates the O2 sensors are probably not good and they are mis-fueling the car through the short term feedback. I have been running my car in semi-open loop with good results - can't even tell the difference when I enable or disable the semi-open loop - but I think I am going to lose the sensors and go open loop just because my car is pretty much a race car these days and gets driven very little - O2 sensors don't like short term running, they don't stay very clean.

[BowlingSS]

I am just going to leave it in OPEN LOOP. Forget those O2's.:exactly:

Bill

[oztracktuning]

I had mine in semi open loop - but find that it runs nicer at idle in open loop. I think the constant going up and down in afr can be felt in the car - maybe other adjustments to the injectors would help this - i tried some - but i dont know if i can get it to idle as good now in closed loop. Have a WBO2 in the car all the time anyway

[Black02SS]

I have yet to hear anyone say that their car runs better in closed loop then open loop.

[ringram]

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?

[GMPX]

One of the other problems was the inconsistant fueling when hot and running full open loop, but of course we have a fix for that.
I think I might run mine in Open Loop from now on, it gives me an excuse to do some logging again just to make sure BEN is all good.

Cheers,
Ross

[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]:coool:

I want one of those.:exactly:

Bill
:cheers:

[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.

:banana: :beer: :cheers: :master:

[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.