2000 Toyota Celica GTS, Code P0505, Bogs Down on Acceleration

by Marc

Hello I have a 2000 Toyota Celica GTS 1.8l automatic 4 cylinder. I am having the biggest problem out of it. When I leave for work at night and the next morning I go to start my car, and it starts just fine but when I go to accelerate it bogs down like crazy. I just replaced the catalytic converter, crankshaft position sensor, new muffler, new NGK spark plugs, new oil/oil filter, it has 142k miles on it and its a TRD Motor, injen cold air intake. It is pulling the code p0505 and I cleaned the IAC valve and throttle body. Does it have and egr valve? Maybe my problem is a dirty fuel filter? Throttle position sensor is good. Also it idles pretty high and then goes down really low. I am stuck and need help please?



Steve Says,

Hi, Marc. Thanks for using my website.

The first thing that I would suspect is your IAC or idle air control valve. This is a valve that is normally located on the throttle body. The purpose of this valve is to make it so the computer can control the idle speed of your engine. to do this the computer read the engine speed and then sends an electrical signal to the IAC. The idle air control valve consists of a coil of wire with a pintle attached to it. When it gets a signal from the computer the pintle moves in or out. This pintle will either cause an air opening to get smaller or larger therefore making the idle go up or down.

The first thing that I would normally suggest it that you clean the iac. Since you already have done that you can move on to the next step. You should try to unplug the connector to the idle air control valve. Then re-check the engine codes. This will probably produce some other obd 2 codes but don't worry about those. If the code comes back with the iac unplugged then you probably have a problem with the wiring to the iac or a problem with your pcm (your cars computer). If the code does not come back then you probably have a bad or faulty iac. Most likely the wiring inside the valve itself has shorted together or might have an open circuit.

It sounds like what might be happening is that your iac is letting too much air into your engine. This is causing it to run lean and therefore stumble when you try to accelerate. I think if you can get to the bottom of this iac code you can probably fix this problem.

Your car does have an EGR valve but I would not worry about trying to do anything with the EGR system at this point. Since you have a check engine code already you should focus on fixing that first and see if that fixes the driveability problem.

I hope this has helped. Feel free to comment back if you need more help.