I'm experimenting with MPG here & have read many other posts; My Question is: when my tune is commanding Open Loop, (IE, closed loop is enabled at 284 F)
Why do I have a LTFT that varies ???? Shouldn't me LTFT be 0 being I'm in open loop????
I'm experimenting with MPG here & have read many other posts; My Question is: when my tune is commanding Open Loop, (IE, closed loop is enabled at 284 F)
Why do I have a LTFT that varies ???? Shouldn't me LTFT be 0 being I'm in open loop????
Reset your fuel trims. Also need to set your open loop table, as the commanded AFR is all over the place.
Russ Kemp
forgot to reset FT's :P oops. I remembered to do that this morning & I do have the OL AFR table set; I posted over here at the end:
http://www.hptuners.com/forum/showth...741#post327741
That has my tune, and scan & cfg file.
Once you set your open loop table to the fueling you like, then log the AFR variance on average and apply that to the AFR table. Of course this is best done after the AE/DE is tuned. It worked great for me, it basically helps keep the AFR right where you want it. I was able to get rid of any AFR spikes and the fueling hit the target very well.
Just make a custom PID that subtract the commanded AFR from the wideband. Log a histogram that matches the OL AFR Table, apply when enough data is achieved in log.
What is cool about OL is getting the most bang out of the drive. Once you find the optimal AFR for RPM vs CYLAIR, the engine will LOVE open loop.
Keep in mind, this is a personal trick I developed. I didn't learn it else where so be cautious, as always with trying new things.
For me having turbo, it allows me to have optimal NA AFR of 12.4 out of boost under moderate load, 11.4 in boost and 15.7 in light cruise.
I ran a switch on the narrow band o2 ground wire. If the switch is closed, closed loop. If it is open, the PCM looses ground and sees no O2 and goes open loop. Easy in dash switch for performance mode (open loop) and casual mode (closed loop).
Last edited by TurboGP33; 06-27-2013 at 09:11 AM.
Thanks for the response; I have been reading / learning & then reading many more threads; this is a great board with lots of opinions & lots of expert advise...
@ Russ, if you look at the scan, my AFR was 16.3 the whole time, (not all over the place) It did drop in the 11's when I enter PE mode, but that was at high TPS, which was expected, as far as I know, the rest of the time it was a constant 16.2 or 16.3 according to the LC1 wideband ??
@ Turbo GP
I currently do not have AE / DE tuned; AE is currently disabled at WOT; however to protect the engine, I have PE enabled at 45% TPS for under 3200 rpm & TPS gradually drops from 45% to 20% as I hit higher RPM.
Fuel -> Open & Closed Loop -> OL-AFR - I'm commanding 17.4 from 140 Engine coolant temp to 230 ECT. (I think the stock ECT thermostat is about 200, which is what all my scan logs have.) So, my question, is, why isn't my wideband LC1 going above 16.3, it seems to peg out at 16.3 and just stay there. I can command 20 AFR and it stays at 16.3. (I have my CL enable temp set to 284) so I know I'm in CL.
I do like your idea of a switch instead of uploading a different tune. Currently my OL AFR adder vs CYL vs RPM table is all 0's (I know I'll need to modify this to make for better stock driving conditions, but I'd like to push timing & higher AF ratios before I get into the fine tuning of better drive ability ..) I'm still wondering why I can command 17.4 AFR and peg out at 16.3 ????
I said your commanded AFR, not your wideband AFR. And good luck using a LC1 wideband.Originally Posted by Ace25
Russ Kemp
I know the LC1 has had some issues form what I have seen on these forms, but sometimes it performs as expected??? Do you recommend a different one? Also, shouldn't my "Commanded AFR" be very close to what the wideband is reading?
(If I'm reading into this correctly, my wideband might be completely inaccurate??? ) this is certainly possible, but when I put the car in CL, the norm cruising AFR seems to be 14.7 ish, and that jives with my wideband LC1.
I really want to know what's going on, so if my wideband is crap, I'll get another; which do you recommend?
LC-1 may peg out @ 16.3:1 easy to test pull the O2 and lay it beside the manifold/where ever it is see what it goes to that will be it's max. make sure you let it warm up. If you want to test it's max A/F take an lighter to it(don't light the lighter) mine is 20.3:1 and 9.2:1 it's not a LC-1 though
Lambda for CNG is 17.2 : 1 (and supposedly this wideband can be used for that...) I'll see what MFG specs are. Never though of taking a butane lighter to it...
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