VCM Controls - Closed Loop Disable, does it work?

[reactor2]

I was spending some time tuning my MAF and I wanted to see how the MAF behaves above 7000 hz. I went to the VCM Controls (Displays->VCM Controls) and turned off "Closed Loop" and "Fuel Trim Learn", and I pressed "Reset Fuel Trims". The STFT and LTFT was set to 0%. I ran the MAF up to 11000 Hz and noted Lambda of 1.0 +- .01 all the way up. Afterwards I looked at the Table Display and both the STFT and LTFT had values. I thought this was supposed to be disabled? Was I kicking into closed loop and the PE table? I thought this was supposed to be disabled.

Do these buttons actually work? It sure doesn't look like it.

[Russ K]

That is because you were logging fuel trims before you disabled closed loop.

Russ Kemp

[reactor2]

That is because you were logging fuel trims before you disabled closed loop.

Russ Kemp

This is what I did (I followed the Greg Banish DVD on this):

1) Start vehicle
2) Start Scanner
3) Open VCM Controls
4) Disable close loop
5) Disable fuel trims
6) Reset fuel trims

Did this result in a no-op? That is, was closed loop and fuel trim learn enabled?

Thanks for the help.

[reactor2]

I contacted HP tuners about this and they said that they use the same commands as GM's tech 2. Whether or not its working on my application, I don't know.

Can someone validate my observation:

My vehicle was originally tuned by a reputable tuner for big cam, heads, intake, headers, etc. and was tuned to command around 12.2 afr WOT. I've since added a supercharger (PISC with 4.25" pulley), giving me pretty low boost (4-5psi). I did spend some time tuning the MAF (NOT using the VCM Controls to disable closed loop, but rather the editor). The fuel trims were definitely being adjusted but since the computer was holding the AFR to pretty much 14.63 all the way to 11000 Hz does this seem like the system was not entering closed loop but rather using the MAF table and fuel trims?

Since my PE table was originally set up to target 12.2 (pre-supercharger) I would expect it to have been richer than lambda if the PE table was being referenced.

[reactor2]

Ok, I had this completely back-a$$wards. I'm an idiot, I had my terminology backwards. Open loop is where 02 sensors are ignored and closed loop is where they are used. So wether or not i had closed loop disabled (i.e. VCM Controls->closed loop off) near full throttle I was indeed entering open loop (02 sensors off, using MAF table, etc.) so I was using my MAF table and PE. What threw me off was that I was seeing 14.5 at near WOT up to 11000 Hz or so.