Really could do with some hand holding type help

[stigmundfreud]

Firstly here is my log: http://www.stigmundfreud.f2s.com/Log_0002.efi

secondly I created my pid selection with this thread: http://forum.efilive.com/showthread.php?t=240

thirdly: the Car is a UK Monaro/GTO with an LS1 5.7 block

Fourth here comes the hand holding....

I bought my scanner a few months back from ringram, he and a few here gave me some help getting logs etc but time passed, the tool lay in the boot of the car until today.

I downloaded the new version of the scan software following a PC reinstallation and I am sure I was able to record the injector duty cycles before but no longer can find the PIDs for it. Am I missing something obvious?

Either prepare to laugh/cry at the next bit OR applaud me on getting somethng right, I'll leave judgement for later:

Open Loop/Closed loop

Also could someone take the time to explain open loop/closed loop for me? I have tried to read up on it and it seems to be closed loop when using the MAF/O2 sensors and open loop when using the VE Table? My understanding is the MAF only really works over a given RPM so the car runs open loop until the maf can operate then it closes the loop?

If my understanding of this is correct, looking at my logs you'll see it seems to mostly run closed loop and only sometimes goes to OL-Drive? Sometimes it does this with 0% throttle so on a deceleration, sometimes not. The conditions seem different.

Either my understanding is completely wrong (in which case laugh) or I'm just not getting my basic understanding quite right (in which case cry).

[dfe1]

I'd consider holding your hand, but there's this distance problem, not to mention the fact that I'm not really sure if you're my type of girl.....

As for open/closed loop, the goal of every original equipment control system is to maintain stoichiometry, which is the chemically ideal mixture of air and fuel. Nominally, that ratio is 14.7:1 and depending on the system you're working with, you may see 14.63 or 14.68 as the commanded air/fuel ratio (B3601 parameter in LS1/LS6 systems). Closed loop operation is designed to maintain stoichiometry by using feedback from the oxygen sensor to make the necessary corrections in fuel flow. Narrow band O2 sensors are actually toggling devices and as opposed to maintaining a specific voltage that corresponds to a specific air/fuel ratio, they toggle back and forth, between rich to lean-- rich being higher than reference voltage and lean being lower. Actual air/fuel ratio then varies continuously, and achieves an overall average of 14.7:1. Closed loop operation is completely independent of mass air, speed density or any other control protocol. In open loop, feedback from the oxygen sensor is not used, so the actual air/fuel ratio is determined by the stored fuel calibration data.
Hope this helps.

[stigmundfreud]

somewhat and thanks, I'm probably not your type of girl ;)

sorry to ask another question but seeing as I have your ears, in my log I see it change from cl to ol what conditions are met to switch from closed to open?

cheers

[5.7ute]

Closed loop will occur after the engine has reached operating temp & an EQ of 1.0 is commanded. When you go into Power Enrichment mode (PE) the computer will slip back into open loop & go off learned data in its fuelling calculations. So basically closed loop is when an eq of 1.0 is commanded. Open loop is when anything but 1.0 is commanded.

[dfe1]

As 57ute pointed out, closed loop operation is active only when commanded air/fuel ratio is 14.7:1 which is an EQ ratio of 1. The transition from open to closed loop after start-up is also affected by timers and/or operating temperatures, depending on the system. Power enrichment is an obvious condition that is associated with an EQ ratio other than 1- less obvious is decel fuel cut, so if you see the system indicate open loop on deceleration, that's probably the reason.

[stigmundfreud]

cheers guys! :cheers: