OL Tune reports Stoich force CL and lean? Help surge, fuel trim, Can I run CL idle/OL
I have my OL SD tune and WB running 14.5-15 idle and part throttle 12.8 and wot 11:1 all OL. I have VE smoothed but IAT I think effect swings with temp. Morning I run 13.8-14.6 cruise and idle and afternoon heat and traffic I will be 14.2 to 15 but it?s feels and sounds great. Little soggy down low I think but rips after 2500. turbo 3200 stall 2deg overlap cam 411 SD 2 bar tune.
I am seeing OL run on WB at commanded across all RPM. At idle since I have a small overlap I don't see the lean effect but maybe I am and over fueling to get to 14.7. Either way car runs good except I am feeding lots of base idle air and randomly surges coming to stop and feels off. I have to idle at 900RPM in OL otherwise it struggles no matter the timing. I disabled all ST/LT fueling and air just have adaptive air values and surges. I tuned part and WOT and it runs pretty strong still dialing it in but I usually within 5% up top and no knock. Only KR I see is I think noise. Usually off throttle after I hit boost on quick stab of pedal and let off quick it will give a KR blip on return of KPA. I have noticed KR on immediate throttle from 0mph, small like 0.5 - 1.0 degree randomly if I move pedal fast. I kept changing timing but still there. So I figure it is fuel, which means too rich off idle.
STFT read 0 and LTFT usually sit at 0 or -1.6 in OL
I wanted to go back to CL to try idle surge. Same tune I forced CL and the idle immediately improved and even ran perfect at 750RPM. But my WB and NB readings reversed? So I leaned out my idle columns by 10%. I was at 5% under stock tune now I am about 20% in the 800rpm cell. I enabled CL in a new tune, smoothed 400-1200 to 10% less VE but I left STFT, LTFT,Proportional Idle and OL STFT all disabled. Biggest head scrather is why my WB/NB switch signals on same tune?
Car drops into idle great and I can do 750 probably lower NP.
IAC go from 125 range to 100 in drive and 60 in park.
cars sounds great and surge is gone. Air tables are probably a little jacked from my OL tune but its 100x better.
So in OL tune 93 and log attached
OL WB = commanded AFR 14-15 range. Idle through part throttle all 13.8-14.8 WOT 11.1
OL NB are pegged out at 800-1000 range
OL IAC is always high and hunting 120-130 at idle
OL STFT/LTFT are 0 and -1.6 all the time
OL idle surges hunts only 900rpm
CL tune 98 same tune with CL enabled and 10% VE out at 800/1200.
CL WB is lean 17-15 between 800-1600, sit at 17 at idle. part throttle though 1600-2400 still reads lean 15-16?
CL NB swing ALOT sit around 520s idle 800-1200 rpm range and go into 550+ in cruise cells.
IAC in CL respondes much more as expected sits under 100< and at idle even 60
CL surge goes away. Idle feels perfect and sound 100x better.
STFT are alwasy negative and very high all the time. like -28 until WOT.
SO with all my fuel trims disabled, even though STFT and LTFT are reporting pulling fuel are they really doing anything? If so is that why I am always reading lean on WB even though NB reads rich? over 450MV
That is my biggest concern. I tuned VE in OL and its pretty close now it looks like go into CL I have to dump 20% more fuel 1200-2400 to get close to 14.7 which the WB never responds too, gets worse actually. OL its fine.
I can play with the O2 swing but haven't touched yet. I tried upping the MV swings to 690 but nothing changed. Trims report high.
What I am i missing in OL that car cant idle well? usually it is the other way around?
If CL is better I am ok, I can run at 17 if I know its not truely pulling fuel and just a false lean from my came and turbo headers. I am using the same VE table. Yet in CL I had some knock under load where in OL I dont, I do not know if the fuel is changing even at part throttle and wot? the STFT/LTFT are reporting but I have things disabled?
It would be great to run CL idle if I cant get OL to work below 2% TPS or 2000 rpm that way I am not wasting fuel, not surging, and not stalling in reverse or coming to a stop. then OL it for part and WOT.?
where are your narrowbands? being too close to the turbine wheel can give false and conflicting data from turbulence.
with a decent cam its common to have false negative fuel trims of up yo -15-20% use your wide band to tune idle even when in CL. don't put it too close to the turbine for tuning areas with little exhaust gas flow. don't be worries about negative trims at idle with a cam in CL just use wideband data and be a little ignorant with STFT for idle and off idle. more than -20%STFT at idle isn't really good.
you can play with your 02 sensor integral delay data for improvement also if you wish.
closed loop idle and cruise in my opinion with a cam that isn't ridiculous in SD returns better drivability. throw a cam with 108 or 110LSA and EFI I need full OL for good cruise manners
Thanks for the reply! I have a 226/232 112 +3 2 deg overlap. Well played all day with tune. Since CL it idled well I went back to OL and got it much better. Since lean idle was better in CL I dialed i open loop to around 15.8 and it feels good Surge is almost gone now, need to redo RAF since idle air is much lower and I can run lower RPM in both modes but CL idle is still nicer.
I went thru my VE and made sure in 400-1200 I have around 15.5-15.8 and 1600-2000 I am targeting 15.1-15.5. Reason being is in 1600-2000 I think I still have reversion effects. When it was 15 and I richen until it hit 13.8 couldn't get stable 14s. then after all that added fuel next run reports lean again on WB. If i back off and run 15 it is stable and feels good. in cruise mode and getting on gas a little it will get to 14.8 range then settle into 15-15.2 then after few seconds of no throttle input it starts to flicker all over. But my NB always report rich throughout most cells except WOT it is 600-700mv and where I am 50% throttle or more it is 900s. So when WB is lean my NB is rich 500-700 when my WB is stoich it flat lines to 900 when WOT it is 930+
My NB are in my turbo header about the front of the motor on each side I guess my the power steering and AC on left/right. My turbo is front and low center. my WB is about 3-4 feet back in the DP, open exhaust probably right under driver seat.
So: Since 400-1200 are idle tuning my VE OL to 15.8 is right correct? what baout 1600-200o is it ok/normal safe to run 15s still. I can add fuel to where it was prior to CL tuning to get 14 but then its knife edge and too rich. (smell, soggy throttle and knock because of too much fuel, I can hear and feel it bog) now it rips.
Before with 14s OL tune I was soggy on throttle to 2800rpm and around town cruise to get into 40mp I was into 3000rpm and 100+kpa. Now with this tune approach in both CL and OL I cruised around town with instant throttle response, little to no surge, and never went above 75KPS or 2400rpm and I was at 50mph.
I am confused on CL o2 tuning. I adjusted my rich/lean vs airflow in modes 0-10 from 400s to 650 across the board matching mv in my logs. I lowered both Prop Idle and just Prop error modes to 0.08. I didnt touch integrator delay. And o2 and fuel trims are the same. Now I have all my fuel trims disabled. I am seeing -20 at start and -8 to -18 range driving. And my WB is reading 1 point more lean in CL then when in OL with same VE table? I also get some knock part throttle and WB goes to 18.
my average o2 readings are always rich in the 590-650 range. Also when I idle cruise sometimes the o2 flat line rich at 900. So it always want to pull fuel. Seems hopeless. Unless I have to pull even more fuel out of VE and tune everything to 16-17 range up to 2000rpm. I am lost with CL.
Well I answered many of my own questions. I wanted to update here for future tuners who might have same issues. Many of these 'insights' are already listed here and basic but sometimes its hard to put into practice until you experience some of the cars reactions.
1: Idle Surge OL vs CL. I think a good test for me was to enable CL and see idle disappear almost. Which tells me it was not mechanical issue but a tune. Since timing was kept the same it had to be the Fuel.
So I checked my VE, it was already pretty smooth so I was confused. Then I saw my LTFT/STFT are always pulling fuel in CL. Meaning its rich. I know me custom turbo headers wreck havoc on the NB O2 so I ignored this absolute number of -30 but relatively its saying my car is rich, even though my WB reads lean. So I removed 14% in the 400-1200 range. This 14% brought the total from stock down to 20%. Again common knowledge but....
In OL now the car immediately idled better and surge almost went away. WB still was reporting lean but not As lean at 17 now more around 16s Weird right, less fuel got richer? Also the NB now started reporting a little more. Not just sitting at 900 flatline. Cycling a little bit. But in CL they cycle like crazy. Whys is that? I suspect, again, it was the fuel trim, it was still pulling fuel, and getting into normal range. I was seeing MV ranges for idle 800 range now in the 400-500 range. I was happy but it was because one bank sits 900 other at 100 at idle once I take off they both peg to 900 with occasional cycles all in OL. In CL they cycle all the time.
1200-2000 I was still in the 16 range but my VE was consistent so I was leaning out and NB report 500-600 when on throttle and 17 at cruise still. I added fuel and it got leaner, take away not it still stayed at 16... Looking at NB I noticed one bank would hi and one would go low off throttle and on throttle they both would peg low. I added fuel in VE and tried in Transient too and nothing work, if anything I added knock and it felt/sounded rich. NB and WB read lean.
So I added timing since I had pulled so much out to be safe. I dropped like 4-6 degrees from stock files. I am 21 idle and ramped into 24-27 upt to 2800 then 33 in hiway cruise. it felt lazy anyway so from 1800-2400 I smoothed in 2.5 degrees and the WB immeidately started reporting 14.7 as soon as I hiot the pedal and go over 1200rpm. It idles back to 16 range. I still have some knock right off throttle in the higher load. 0.32-0.36 800-1400 rpm range. I am at 21 degrees flat until 1200. I am going to smooth in more timing it has to be bogging and wanting to create more load to burn the fuel.
I also see this helped solve the split NB issue. one hi on low. I think timing was so low that air and fuel were just blowing out the exhaust and getting rich knock even. I was going wrong direction. I was adding more fuel and not touching timing. I am going to leave VE alone for now. and smooth in a few more degrees up 2800 then revisit VE curve for final touches.
I think idle cruise at 15.8-16.3 is fine and a false reading on my WB. NB are around 450 in park and 390 under load and light cruise no throttle but typically look rich. 1600-2400 is the main driving area I will shoot for 15 in 1200-1600 since I think it still has some false readings and get to 14.5-15 up to 2400. By 2800 I am usually 14.5 or in PE at 11.1
Another thing I learned was transient fuel, or big fuel changes were causing knock. I had transient fuel at 60g.s and 127g/s to get some quicker part throttle fueling so it would ramp in quicker from 14.63 to 11.1 but I noticed my KR (small but still) usually 0.5 was alwasy at 60 and 127 g/s. So I took the 1.10% value and went back to 1% and it went away. I also kept removing timing to get it to stop and it kept coming back. getting richer and richer on top of things! So I will add that timing back to up top once cruise is done.
Reply With Quote