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For the last 3 months I have been using open loop and it has been such a improvement in smoothness that I doubt I will switch back. It also allows me to effectively have highway lean cruise, fixed a little roughness at low rpm O/D locked converter, and a number of other things. Post really was to ask how many others do open loop.
I leave mine open loop, mostly because I'm too lazy or forgetful to turn closed loop back on. I also like to keep an eye on what's happening through my TunerView II even without the laptop connected, so I can make appropriate adjustments without closed loop causing me to see something I'm not.
I also leave a friend's car open loop, because of the cam overlap, at idle and low RPM, the AFR readings swing so wildly that open loop just runs better.
I have a 94 LT1 that been running in open loop for about a month now and love it. Throttle response, power, smoothness and idle is much much better. I just wish I had WB O2s so I wouldn't be tuning blind. Right now I know this motor has way more power up top and pulls hard after 4K but not like it should. Doing more testing today if the rain holds back.
i run full time open loop, on my daily driver, even with my relatively small cam.
closed loop is the enemy of a perfectly efficient and smooth tune, imo.
my engine really wants ~14.0 at idle. sure i can hack open loop idle...
but it also really wants 14.2-14.3 under moderate load around 60-70kpa, stoich just isn't quite enough juice.
also really wants around 13.8 at heavy load. the stock tune usually would have pushed itself into power enrichment at this point, which is super rich and unnecessary in some cases.. now i have control over that.
it also likes being nice and lean during coast/decel, where i spend most of my time, 15.5-16:1 seems to be a sweet spot. im careful to only run that AFR at 0-30KPA, and it's very happy about it. running open loop saves me a ton of fuel. edit: also noted that this region is the transition point into DFCO which is SO smooth now.. DFCO pops from lean to nothing very easily, but if you catch closed loop at the wrong point, it could be 15:1, could be 13:1, who knows (closed loop is awful during decel)
even further than that... there are low rpm areas out of regular operating range where it gets a bit stumbly and rough. running extreme timing advance can keep it from stumbling, but you can feel the engine hates it. all i have to do is throw a bit more fuel at those areas in the VE table to smooth it out. if i was running closed loop, it would remove that additional fuel, and probably not gently either...
maybe a modern or standalone ECM lets you configure areas which are closed loop and not, in which case i'd love to run closed loop in a box about 30-60kpa 1800-3500rpm large... but in my case i'd rather it stay out of my way.
I'm full time open loop as well. I find that I have a much better off idle throttle response in open loop vs closed loop. I'm running a MAF open loop, but thinking of using SD and getting that dialed in also.
And I'm on a completely stock cam. I will say that no matter how much I messed with the tune I had problems with closed loop idle ever since my long tubes went in.
do it, it's worth it. the map sensor and opti respond WAY faster than the stock lt1 maf. it's a subtle difference but you can certainly see it on a wideband if you blip the throttle.Quote:
but thinking of using SD and getting that dialed in also.
Isn't there a way to force open loop at idle now without using the PE trick? Or did I dream that and not read that?
for $EE, kur4o was working on a patch, i tested it and did not have good results. i think it's at a bad part of the loop, it managed to go open loop at idle but would not return to closed loop. but it's promising. my car doesn't have narrowbands anymore so i can no longer test patches like that, unfortunately.Quote:
Isn't there a way to force open loop at idle now without using the PE trick? Or did I dream that and not read that?