Hey there, I've got a 91 DA integra with a N/A jdm b20b swap running on a hondata s300 P28 ecu.
From time to time I will get this hesitation on throttle tip in or light throttle cruising, especially bad near ~2200 RPM. When lightly picking up the throttle after a lift, it briefly hesitates before resuming acceleration/cruising. When it stops hesitating it jerks back into acceleration and it's quite annoying. Asides from throttle tip in, it also occasionally will just cut out for a split second on steady light throttle (in the ~5-7% TPS range.) Now here's where it gets odd; The stutter/hesitation occurs at random, one day its fine the other its not, it goes away for days after pushing the car (ex. a good autocross or track day.) I replaced the TPS sensor which fixed it for ~8k miles before coming back, messed around with overrun fuel cutoff settings and TPS calibration. The overrun settings did make it less jerky, but still hesitates/cuts out. I have an AEM wideband and it seems to only happen after I've lifted for long enough for overrun cutoff to engage (leans out when coasting as intended), and when it cuts out mid cruise it leans out as if hitting overrun fuel cutoff. To me it seems like the ECU is seeing an incorrect TPS value at light throttle and thinks I'm lifting when I'm not.

Other things to note with diagnosis: 66mm TB, Sk2 pro manifold, Sk2 alpha header, tuning in open loop, fuel and ign tables are good and clean

Any input is valuable, thank you!

 

Does it do this in open loop or do you turn closed loop on when done tuning?

 

It’s in open loop full time, AFR goes lean during the hesitation which of course leads me towards a fueling issue, however fueling on the tuning side is good and the fuel system is relatively new

 

Maybe check the ignition system.

I have also found that lack of ignition will cause lean conditions. Raw fuel doesn't register as rich.

Thats called a false lean