As the title describes the car is a 92 eg w a b18b1 completely swapped from a 96 ls integra. Recently at a constant throttle (me holding the pedal steady) the rpm's are fluctuating about 1k in either direction. When accelerating i notice a hesitation at times. Other times i notice a substantial power loss, hesitation, and then normal operation. When i unplug the tps and allow the car to run in the default map or "limp mode" the problem is gone. I changed the tps to no avail. I swapped the ecu with another p75 and once again with a p28 w hondata s300 loaded with the stock b18b1 settings. Problem remained with both ecu's. Full tune up done recently on the engine (plugs, wires, cap, rotor, timing belt). I checked the fast idle valve and cleaned it. I even swapped with a known good part. I Datalogged with hondata and all the parameters for the sensors read good as far as i could tell. I suspect possibly the o2 sensor since it is shown in voltage on the log rather than a/f ratio. I will research the conversion from voltage to actual ratio and see if that is an issue. Also i have had a mechanic tell me possibly the crank sensor could cause this conditon. ANY INPUT IS GREATLY APPRECIATED. I dont really want to throw parts at it so any info regarding testing is also appreciated.

 

Idle fluctuation as a general rule is caused by too much air or too much fuel, or a bit of both. Air problems are more prominent on Honda's, so I would start by looking at the fuel trim tables with a scan tool capable of reading them, as well as monitoring other sensors such as throttle angle, coolant temp, etc.

But first, what was the last thing done to the car before this started happening?