Hi, This problem has been persistant now for 1 year with a long history or trying to fix it. It just started all of a sudden one day in my 93 civic si 5 speed hatchback.

When the car is warm, when I accellerate off the line, I have to rev it up high otherwise there is no power and it sounds like it is misfiring.
When the problem starts I resolve it by letting off the gas slightly, then it has full power all of a sudden. There are no CEL codes.


I have replaced the following to try and fix this but nothing has made a difference.

ignition system (entire module itself including cap and rotor) cost $300.
new plug wires, plugs checked (not changed).

changed coil and used an MSD blaster 2. Did not fix problem.

changed map sensor, fuel injectors, fuel filter, o2 sensor.

topped up coolant.

I have not used a timing light to verify the timing. But when I made the timing more advanced by turning the distributer cap to the right, it lessened the problem for a while.

Also, I unplugged a few sensors and that made a difference but the same problem is still there. I unplugged the tps, the IAT, the coolant temp sensor.

I noticed that the coolant temperature sensor combined with the TPS sensor made a big difference but still when the engine gets hot the problem is very bad. So I am driving without a TPS or a coolant temperature sensor plugged in.

I am thinking that it may be a slightly faulty fuel pump ? otherwise I have no idea.

Any help would be greatly appreciated.

 

Does the CEL work?

Is the problem eliminated by unplugging the O2 sensor?

Have you checked the mechanical timing?

 

I replaced the o2 sensor twice and that did not work. Problem still persists.