1999 d16y8 p0505 ideas

[mcnabb_nfl]

I have a stock 99 EX and recently it's developed the p0505 issue. I've seen this on many threads but none of them seem to come to a conclusion, so I'm looking for help!
At around approx 1500 rpm engine pulses erratically with throttle pressure, and releasing and reapplying pressure to the throttle while driving produces a violent jerk. The car will buck if you are in that 1500-1700 rpm range. This only happens when the car is at operating temperature.
1. Sitting at a light, the idle will suddenly rise about 400
2. Cel will immediatly come
3. What I described above will happen
If I clear the cel while driving the issue suddenly goes away but will come back a day or 2 later. So far I've checked for vacuum leaks and cleaned the iacv, but that only worked for a few days. Please help!!! I have a scanner that shows some live data if that helps!
Ps: car also has p0420 which is a cat code and is probably unrelated FYI

 

[XpL0d3r]

What have you tried so far to fix the issue?

I'd start by cleaning the IACV. Also, P0420 is not necessarily a cat code, it's also for your primary o2 sensor which can affect your idle greatly. When the car is cold it does not use o2 sensor feedback as it runs open loop. When it gets to operating temp it then uses the sensors. If you have a bad primary o2 sensor that could be the source of your issue.

I had a similar issue (bogged down HORRIBLY in low RPMS, but was fine once they got higher).

Good luck!

EDIT: http://engine-codes.com/p0420_honda.html

 

[mcnabb_nfl]

What have you tried so far to fix the issue?

I'd start by cleaning the IACV. Also, P0420 is not necessarily a cat code, it's also for your primary o2 sensor which can affect your idle greatly. When the car is cold it does not use o2 sensor feedback as it runs open loop. When it gets to operating temp it then uses the sensors. If you have a bad primary o2 sensor that could be the source of your issue.

I had a similar issue (bogged down HORRIBLY in low RPMS, but was fine once they got higher).

Good luck!

EDIT: http://engine-codes.com/p0420_honda.html

Yeah I tried cleaning the iacv twice, but both times it only fixed the problem for a day or so. I don't really want to buy a new iac valve just yet, because a lot of people have tried that with no success. Thanks!

 

[bisho23]

i have the same problem i replaced mine with one from junk yard and helped for just a little bit and im throwing a catalyst code

 

[XpL0d3r]

i have the same problem i replaced mine with one from junk yard and helped for just a little bit and im throwing a catalyst code

When's the last time the car had a tune up? Plugs, wires, inspected distributor?

Also, how is your idle? Please create your own thread with as much detail as possible. Thanks!