Been having this same issue since i bought someone elses swap. B16a2 on a stock p30 that ive put over 10k miles on. Sputters heavily on startup and idle is low for a few seconds, then bounces up to normal. Every once and a while it stalls on startup but not often. If i start to drive before car has warmed up, it will more often then not sputter and hesitate power delivery. Idle generally sits low at 300 rpm but sometimes bouces up to normal 5-600 when at operating temp. Idle drops off when coming to a stop and occasionally engine stalls. Throttle response sometimes feels hesitant and lacking response but will usually kick back in after a second. The only code is an occasional knock code but my engine isn't knocking. Ive checked vac lines, replaced iacv with new oem, new calibrated tps, new rotor cap wires and plugs, voltage tested battery, checked fuel pressure to filter and probably more im forgetting. I even took it to a local shop that is normally suggested for hondas and they had it for 2 weeks and gave it back free of charge because they couldnt fix it. Could it be my brake booster? My distributor? Alternator? Ingnition? Valve lash? Im pretty at a loss and would love for my car not to die on me in traffic on occasion. Any help is appreciated!!

 

What car?

Fix the knock sensor code.

Bleed the cooling system, clean the IACV, and then adjust the idle speed as per service manual.

 

Its a 94 civic hatch. The knock code only throws occasionally from the connection to the wire (not my work), the denso sensor is less then a year old, and my engine is not knocking. My iacv is less then a year old, brand new denso. And coolant is about to be changed this month for winter but ive burped multiple times to try to reslove this issue, maybe then itll go away. I have yet to adjust idle screw but to my knowledge it is not something you simply want to turn and feel that is not my exact issue. I try to be very thorough and meticulous. I follow factory specs. It still has the charcoal can, could that cause these issues? Coolant shouldn't be causing my engine to stutter hard on cold start. Every single time. Could an injector be clogged? Im just looking for suggestions on what could be causing this issue or where else to look

 

A knock sensor code can make the engine run poorly. Fix it. Then go from there.

Follow the service manual procedure for an OBD1 P30 ECU.

 

Im not throwing a code currently, like i said it only comes on every once and a while. Forsure thanks for all the help.