Closed Loop idle= Garbage Open loop+fine?

[SeriousSN95]

hey guys, looking for insight on this bastard 97-98 Trans am ive been tuning. Ended up putting new oxygen sensors in it so it would actually enter closed loop. Well now that it does, it surges like hell and runs like crap. Running it in Open loop seems to be the only way to get it to idle worth a damn. I tried Open loop Speed density and it surges like crazy but when running blended VE/Maf it runs great. No idea what the deal is. below are the mods and the file as well. If anyone can help, I would appreciate it. I really would like to send it out in closed loop but at this point ive tried everything with no luck. Thanks! (first file is closed loop file and second is Open Loop file im running currently)

98 trans am
SBE 5.7
MS3 cam
Trick flow heads
92mm Fast intake/throttle body
vararam ram air filter setup
255 in tank pump
green top 42lb injectors
longtubes, 3" y pipe, borla catback
4l60e
Yank 4400 convertor
10 bolt 3.42s

[lukearmstrong1990]

high lift cams with valve overlap at idle will often put unburnt fuel into the exhaust and make the 02 sensors request fuel to be removed at idle as seen with the logged STFT being for example -15% or -18%. the car isn't actually rich it just thinks it is from the raw fuel causing the 02 to command negative trims.

in closed loop with STFT at -15% the car may idle poorly because its actually lean despite the o2 reporting opposite. in open loop the STFT cant do anything so it isn't removing the 15% (example) making it lean resulting in poor/unstable idle

[scoob8000]

Getting my base running airflow really settled down my hunting and surging issues.

Also watch your spark and see how much it's fluctuating. There's a table for over/underspeed where it'll add or pull timing to correct idle.

If you graph your narrowband o2's, do they oscilate properly at idle? Mine weren't all the time and turning off proportional fuel at idle fixed it for me. Not sure if that was the correct thing, but definitely helped in my case.

[SeriousSN95]

added some base running airflow and opened up the underspeed/overspeed tables and helped some. Still running poorly in closed loop. Im gonna keep it in open loop and work on the tune since it seems to run best in open loop. Thanks for all the suggestions. This will def be the last 97/98 I car I tune lol.

[scoob8000]

added some base running airflow and opened up the underspeed/overspeed tables and helped some. Still running poorly in closed loop. Im gonna keep it in open loop and work on the tune since it seems to run best in open loop. Thanks for all the suggestions. This will def be the last 97/98 I car I tune lol.

See if this helps: https://forum.hptuners.com/showthrea...ight=russ+kemp

Basically we log desired airflow and plot it on a chart against engine temp (so the layout looks like the RAF table). Then from a cold start without touching the gas let it log until your up around 200-212 or so. Most guides have you disable the fans in VCM controls.

Copy and paste that chart to the running airflow table. Let it cool, rinse and repeat. Then do the same thing, but with it in gear.

It helped out quite a bit, especially when transitioning from gear to park and vice versa. My tables were a good ways off to start.

The part I'm not sure on, is some guides have you disabling all the adaptive idle stuff while logging. Seems to be mixed info there, but it worked just as well for me without.

[edit] Also try logging your narrowband o2's. See if they're cycling like the should when you are idling.