Okay so heres the scenario:

Up in Canada the winters can get as cold as minus 20-35 Celsius at night. My EF is plugged in all night so the coolant is warm. I start my car, it starts up just fine, idles at about 1100 RPM for about 10 seconds and then sounds like its misfiring and runs rough so rough sometimes that it stalls out. I restart it and its fine or if I give it a bit of gas after starting it will stumble a bit but idle up okay. If its misfiring and I give it a bit of gas it will stumble stumble and stumble for about 5-10 seconds and then idle perfect. I will let the car warm up for about 2 minutes and then drive off and I can definitely tell that its got a loss of power between idle to about 2000 RPM and then it drives fine.

When its warm out or if the engine is warm is perfectly fine. i've replaced the dizzy with some slight improvement, my connections are tight in my dizzy, my injectors are clean, my plugs are new, my fuel filter is new, I use good quality gas and my car doesn't leak or burn a single drop of oil.

What is my engine's problem? No CEL's or other obvious signs of problems.

My car is immaculately tuned and cared for.

The car is a 1991 Civic Sedan with a D15B2 engine.

thanks

 

Operation is normal, there is nothing to worry about as far as the misfire goes, but your idle RPM is too low, it should fast idle at 1500 rpm cold.

The DPFI system acts a lot like a carbuerator, so the fuel puddles when its cold which will cause it to stumble. I have a 3dr hatch Canadian model with the same engine, and it does this when very cold. (-10F and colder) My car is also well cared for, I don't use a block heater, it cranked over in -30F which is about as cold as it gets around here.

If you examine the intake manifold, there are many water connections to it to get it as hot as possible so the fuel atomizes correctly. I first noted this when using the A/C when the engine was cold, the engine started to misfire until warm. The intake pipe in front of the radiator also serves to suck in hot air to provide best fuel economy even in cold climates.

 

I figured that was what the issue was. I was hoping that I could somehow rectify this problem with a simple part replacement. I had an 83 oldsmobile with a 4 barrel carb that had similar issues and that obviously was a result of fuel not being atomized properly.

I plan to convert the thing to MPFI this summer so I guess I have nothing to worry about. My cold engine at minus 20 C idles about 1200 RPM or less....

 

I hate to kill your future hopes but this happens with MPFI as well. My B16 OBD0 Civic runs like $hit when cold, but as soon as it warms up, it's all nice.

 

Mine is the same.. I noticed that the valves tick REALLY loud at cold startup too so maybe a valve adjustment could solve the power loss problem? Mine stutters and chugs before 2k rpm if the motor is cold and it hurts me every time..