I'm having a problem with my 1990 CIVIC 1.5 STD. 3DR, Chassis: ED634, Engine: D15B1.

It starts and runs fine when it's cold.
After running five minutes, when the engine is hot, it begins to run poorly, stalls and won't restart until it's cold again.
When it is warm, if I quickly press the accelerator to the floor, it is almost guaranteed to cough, hesitate and stall.

The ECU displays one short blink upon power up - O2 sensor error.
I've replaced the O2 sensor (twice) with Bosch universal 1 wire sensors which didn't fix the problem.
I've replace many other components including the distributor/exciter, injectors and on and on.
I reset the ECU and the one blink ECU error returns immediately.
I unplugged the O2 sensor (to force it into limp mode) and it still won't restart when hot.

I didn't think a bad O2 sensor would cause it to run so poorly. That's what limp mode is for, no?
Do these symptoms suggest something other than or in addition to the O2 sensor?
Should I swap the Bosch O2 sensor with an OEM Honda replacement?
Any other suggestions?

Thanks for helping.

 

One short blink on power up is normal whether or not there is a code. If there is a code it will blink the code number(s) repeatedly over and over for as long as the key is on. So you're not seeing an oxygen sensor code, or any codes.

My guesses would be weak sparks or the valves adjusted too tight (causing loss of compression when warm). When the ECU goes into closed loop mode it leans out the mixture and the spark intensity becomes more critical. Try replacing the spark wires, use OEM wires if at all possible because many aftermarket ones are crap.

 

The issue is resolved. It was a simple tune up, i.e. new cap and rotor. She now runs like a sewing machine.

 

side note next time do not buy Bosch oxygen sensors only use NTK or DENSO in your honda.