2000 Civic Ex misfiring, codes p0300, p0170, p0171
 

For about a year now i am having trouble with misfiring in my 2000 Ex Automatic. I replace one sensor or do tune up and a month later something else causes the car to misfire again. For about 2-3 months now it was running ok without any misfiring, except it was sluggish especially when it shifter gears to 3rd gear. It almost had no acceleration. But it did not misfire and no check engine light.

Last night after driving the car all day it would not start after being parked for 3 hours in very cold temp outside. Battery was fine because the car was cranking but not starting.

So the next morning (today) i replaced the spark plugs, wires and distributor cap and MAP sensor. Wow and the car ran fine, rpms where at the right speed and no misfire. The car ran like new again.

Two hours after all my excitement i try to drive the car again and it starting like crap and it misfires and check engine lights up. The car has codes P0300, P0301, p0303, p0170, and p0171. It runs fine for 5 seconds it seems after i start it, but than it starts misfiring and rpms drop. It ran the same way before i changed the oxygen sensor in November 2013.


So far i replaced spark plugs and cables (2 or 3 times in 1 year),
I replaced distributor cap,
I changed engine temperature sensor
I replaced oxygens sensor (before catalytic converter)
I tested voltage on throttle body position sensor and it worked fine.
I changed fuel filter.

So my question is, could this be the aft oxygen sensor or same oxygen sensor i already replaced? Or something else?

One more thing, i did valve adjustment last year too and everything was fine for 2-3 months. But it seems that couple of months after that valve adjustment things started to go down hill. The car has now about 220k on it and its hard for me to let it go because everything else on this car is in good condition because i took good care of it.

Please help me guys

Thank you

Re: 2000 Civic Ex misfiring, codes p0300, p0170, p0171
 

If you reset the ECU, do all the codes return after running the engine or driving the car?

Measure the fuel pressure, test the FPR, and check for clogged fuel injectors.

Why didn't you replace the distributor rotor? Have you inspected the distributor internals and tested the coil and ICM?

Re: 2000 Civic Ex misfiring, codes p0300, p0170, p0171
 

Thanks for your help. So today i replaced the rotor, coil, and i checked the fuel pump. Car still runs like crap.

I checked which culinder is misfiring and it turns out its the 2 cilinders on the right side of the engine.

Re: 2000 Civic Ex misfiring, codes p0300, p0170, p0171
 

i have the same problem i replaced wires, plugs, cap, rotor, ign coil, cleaned injectors, replaced the fuel pump, cleaned the idle air control valve, changed the alternator(over charging not for p0300) and it still comes on once month. I just reset the ecu and keep going. Once the check engine light pops on the engine feels like it's miss firing a little bit. In for an answer!!!!!!!!!!