Well, I have removed every emmissions device from my car except the Carbon Canister. So, I believe Open Loop (OL) will work fine with my vehicle - using a 7727 ECM (7730 twin - $8D). [The cam is 222/230 @0.050 with .542/.563 lift. MiniRam III intake with FastBurn aluminum heads. 355 cu.in. with long tubes and full dual exhaust]

I have been trying to research OL tuning on the forum, but have not found too many threads about it. So what am I in for? I would like to try and get each part of the ECM logic addressed, so I will number my questions and thoughts: (here goes)

#1 OL good or bad?:Maybe I do not need to force OL and Closed Loop will function fine, but is there a reason I should try to perfect closed loop if open loop is easier? [If you can convince me that CL is better, than I guess the rest of the questions are void. But I know that 14.7 does not produce the best mpg]

#2 OL general stuff: What does the ECM do in OL? or another way to put it, what tables are no longer used in OL? I know that BLM/INT are locked, and none of the O2 tables are referenced. What else is ignored?

#3 VE tables: I understand that the BLM/INT will be locked at 128. By adjusting the VE tables and using my LC-1, I can make the engine run any AFR I want. For fuel consumption, I can have the VE tables tuned to around 14.7-ish AFR (or what ever produces the best mpg). Is my logic here wrong.

#4 PE tables I can use the PE change to AFR versus RPM and versus temp to adjust AFR for max performance/HP. What about PE spark advance?

#5 AE tables: Which of these would be useful and why? Seems to me that they would provide the same usefullness/function as when in Closed Loop... if I have the VE tables tuned for best fuel consumption (and by that I mean highest mpg) It would be much simpler without them if possible.

#6 Spark tables: These all function the same in CL as in OL, right?

#7 Knock retard: Hopefully these still function in OL the same aas they do in CL.

Anyone else want to add some questions? I am sure I am missing some points.

 

Your on the right track

The os still reports but is ingnored as far as control go.

Open loop can be used to make any point on the curve the exact AFR u wish.

Some people use the PE some do it all in the VE, and some more blend the too.

Whatever works for you.

AE is the same OL or CL.

Timing is also

later
Jeremy

 

i ran OL all of last 2 months of season first month of this. what i did was tune CL to 128. then i enrichened my VE accross the board a certain percentage. flipped back to CL and saw the result at 124. here is where i think i may have messed up. i believe you need to disconnect the battery at this point to lock the VE at 124 as i think it uses a "corrected" VE table if you do not. not sure on that. maybe someone will explain. anyway on the WB i could see enrichment at steady cruise. AE was not affected and neither was PE per WB. also in OL i was able to "crutch" my AE at tip in by fattening up the VE tables at higher map that are seen on moderate acceleration briefly. another advantage was the idle was not falling into "asynch" as it does now in CL idle. but that is TBI related. downside was when the environmental temps changed from morning to afternoon the tune was too rich. with gas over $3.10 and burning midgrade i decided i need CL and that is where i am at today. awaitng EBL ships tomorrow!