1991 Civic Si
94 JDM GSR motor with B16a S1 cable tranny, OBD0 injectors, distributor, and spoon chipped ecu. Running stock exhaust manifold with one o2 sensor. Both primary and secondary o2 sensor curcuits are spliced into one o2 sensor. Car idles fine and is pretty fast when accelerating in vtec to redline. But sometimes when coming from a complete stop and going forward in 1st gear the car just hesitates badly. Like it has no throttle response and won't go forward. I'd have to pull over just to let the cars behind me pass by. I tried swapping a known good coil and set of spark plug wires, vacuum is at 21 inches and tps is at .5 volts with throttle closed. Car is throwing a knock sensor code. The current Knock sensor broke off. I'm thinking i'm having a fuel problem but yet to throw on a guage and monitor it while it's hesitating. Any ideas.

 

spoon ecu is JDM... JDM ecu doesnt use two O2 sensors as far as i know. Splicing both units into one harness is probably making the ecu lose its mind especially if one sensor runs a different voltage than the other...

does it only hesitate if you accelerate normal speed through 1st, and does it do it in like 3rd or 4th at all?

 

What OBD are you running? Stock OBD0 will have 2 O2 sensors, OBD1 will have 1 4-wire O2 sensor. OBD0 will be the PR3 or PW0 ECU and the OBD1 will be P72 if it's a GSR ECU.

 

Using a spoon chipped PWO OBD0 ecu with a 1 wire o2 sensor. Both primary and secondary o2 circuits are spliced into one o2 sensor. Tried running with one of the o2 circuits disconnected and it didn't make a difference. Happens intermitantly when the car is warm and from a stop (rolling speed 10 mph or less) at about 3500 or less rpm. It will have a glitch and than the car will drive like normal again. Hesitation doesn't occur when cruising at all. Tried a known good ecu and still no luck.

 

sounds like its a problem with the motor in closed loop but if that were the case it doesnt make sense why it only does it at low vehicle speeds.