My 90 accord EX with 265xxx mi on her has recently started acting up. While idling the car will sit around 1000 rpm(Which is high but it always idled like that) and randomly it will drop down to about - 200-300 rpm acting like it is going to stall, but never does. Now i have recently noticed that the issue only happens when the CEL is off. Once the check engine light comes on it idles alright. Im completly lost as to what could be causing the issue. I have replaced the o2 sensor( which originally took away the cel), fuel filter, plugs and wires, battery, and oil change with no change. Anyone have some insight?

 

If your CEL is on that is a hard fault, there is something wrong with the PGM-FI system. Two wire connector should be behind the kick panel on the the passenger side. Jumper it, turn ignition to II(ON) and read the CEL code.

High idle is usually attributed to the FITV out of adjustment, go to the Accord FAQ at the top of the page and look up the FITV/IAC cleaning procedure.
Look for vacuum leaks as well.

 

im not so much worried about the high idle as much as i am with the fact that it stutters and acts like its going to die, but it always picks itself back up to a good rpm range. and the car runs better when the cel is on.

 

I jumpe the diagnostic port and found that it's a code 43. Fuel pump sounds like it's running correctly. So I'm really at a lose of where to start trouble shooting seeing as the o2 sensor was replace less that 2000 mi ago, as well as the fuel filter, and plugs an wires.

 

if you used a universal or even aftermarket o2 sensor it could be that. all other brands are never as good as genuine Honda parts. when I searched about it a lot of people saying a rich condition. im not 100% certain but im pretty sure the o2 sensor is the only sensor that can detect such running conditions.

I believe code 43 indicates fuel supply system. check this out.


http://www.hondaaccordforum.com/foru...-problem-3331/

 

i looked into all the information on code 43 issues. what im seeing is that right when you start the car the cel like is on. Mine is turning on after about 10-15 min of driving, and after shutting the car off and turning it on the cel is off. im due for another inspection and have no idea where to continue looking.

 

If the O2 sensor that is installed is a generic beer can type then it may just be junk. The large body of the O2 sensor takes too long to heat up, may not stay within operational temperature and cool off. This will cause the O2 to not properly function or be lazy.

Note the sensor on the Left is the correct style, Denso, NTK, Delphi/Delco. On the right is a generic beer can style cheap 'Bosch' unit.


ECU is expecting a given amount of cross counts(rich/lean flag switching) per second. If the cross counts fall below this threshold the ECU will ignore the O2 sensor as it is faulty, and will set a code.

If you have a voltmeter you can observe the voltage and see what the O2 is doing.


Here's a good read on O2 sensors, http://www.aa1car.com/library/o2sensor.htm