ECU Tuning & Fuel Management - Idle system problem Code: P0505

Hello,

I'm helping a friend of mine with her 99 Civic. A few days ago, the started idling irradically. When it does this, acceleration is very bad as well. She says that the problem will go away if she turns off the engine and restarts it immediately. While getting some other work done, her mechanic checked the codes and came up with this:

Code: P0505 -- Idle system problem

Unfortunately, the mechanic did not tell her what needs to be fixed. What components should be checked?

Here are my guesses, (keep in mindthat I've never dealt with Hondas before):
EGR valve
Throttle position sensor

She just dumped a ton of money into CV Joints and tie rods, so any easy DIY suggestions would be helpful.

Thanks,
Eric

uh..kappa ,sacicons ..wanna hadle this????

Check the IACV and all sensors. Make sure there are no vacuum leaks.

Not familiar with IACV I'm guessing it stands for Idle (blank) Control Valve. How close am I?

As far as checking the sensors goes, what's the best way to do that? Which sensors do the computer consider part of the Idle control system?

Thanks,
Eric

Idle Air Control Valve

Basically you need to check all the sensors that run to the PCM (vehicle speed sensor, coolant temp. sensor, air conditioning sensors, power steering pressure sensor, etc.) because the PCM adjusts the idle based on the info it receives from these sensors. You can do visual checks on the sensors to check for damage or corrosion. But make sure you check for vacuum leaks too.