I have a 93 civic hatchback si with a b18b1 swap just recently started hesitating at low rpms only while accelerating and only when engine is warmed up. I have already replace fuel filter, cap and rotor, spark plugs and wires. Injectors are fine and no vacuum leaks. No colant or oil leaks and i have ran fuel cleaners and seafoam in the intake but nothing has helped. Tired of throwing money at it so if anyone can point me in the right direction i would greatly appreciate it

 

could be bad engine coolant temp sensor or throttle position sensor.

https://axleaddict.com/auto-repair/C...re-Sensor-Test

Honda Civic How to Replace and Calibrate TPS - Honda-Tech

if you replace ect you'll have the same problem until you bleed all the air out of the cooling system.
it was a bit of a nightmare for a week or 2 lol.

 

ect is new. Pit it in about 2 months ago. And tps tested good. I bled the coolant today there was a small bubble didnt take but a few seconds for it to come out. I realized today that it hesitates a lot worse the more throttle i give it. Could be fuel pump maybe? But it doesnt hesitate at all when im in nuetral and give it gas

 

Check your ignition base timing.

 

sorry didnt update until now. I put dizzy all the way advanced and its much better still hesitates but very little so im going to check mechanical timing this weekend

 

Did you check the timing with a light while your car was at opperating temperature and in diag mode (Jumper)?

 

I guess not lol.

 

This ^ + check your cap/rotor
You shouldn't have to put your dizzy all the way, either direction. And you should set it correctly, not advance it.
But, yes, also check your cam gear alignment.

 

sorry guys i have been busy. Yes i set mechanical timing to tdc and ignition timing with light. Runs great on cold startup but as soon as it warms up it idles rough. Acceleration is good at normal speeds until i step on it then it hesitates. Started throwing code 3 (map sensor) fixed that code # 7 (tps) fixed that. So only code im getting is 41 ( 02 sensor) which ive never had one hooked up and iive had the car for over a year and ran perfect until a few weeks ago

 

So you confirmed that mechanical timing is correct and then set the ignition timing with a timing light, but it required full advance of the distributor? That is weird. Also, you did not confirm that your car was in diagnostic mode with the jumper, before setting your ignition timing....

 

Dizzy is not fully advanced anymore after using timing light i set mechanical timing then adjusted dizzy with light. and yes i used a jumper. Im definitly running rich just pulled spark plugs out and they are black.

 

sounds like poor spark, tested your plug wire resistance?

https://www.ngksparkplugs.com/about-...d-a-spark-plug

 

Maybe low quality or aftermarket Plug wires/cap/rotor/distributor/ignition coil/igniter??