Code P0505 With a Strange AfterMath

So over a month i had a CEL, which was the idle air control valve, i replaced it the IACV with an excellent one. Its still reading P0505, CEL is still on. Last wekk it was idle surging between 1000 and 1500, at warmup it'll stay at 1200. Well this where it gets weirder, Today it wasn't idle surging, instead it was idling at 900 RPM and was driving normally, not like last week. But i still fear for the idle surging to return (it happen on my way to work this morning only). I went to one auto electrician, he checked the code and sensor a few times, explained tht the car's computer has to be reprogrammed in order to be solved, will charge me $140 if it works successfully, should i go for this choice or what are your suggestions?, the car's fate currently lies on this.

Reprogram the cars computer sounds not right at all. The part isn't married to the car by any means.

Where did the replacement unit come from? Junkyard? Start with simple stuff? It sounds to me like you either have a bad electrical connection or a vacuum leak somewhere.

james'99 said:

Reprogram the cars computer sounds not right at all. The part isn't married to the car by any means.

Where did the replacement unit come from? Junkyard? Start with simple stuff? It sounds to me like you either have a bad electrical connection or a vacuum leak somewhere.

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James i wish you were my mechanic, youve been giving me help here n there lol, the replacement was brand new $85 good quality one, it seems as thou the car already got used to its new IACV after two weeks

It jsut didnt sound right either about reprogramming the computer, i will have to check for bad conenctions or a possible vaccum leak.

The surging is ussually the iacv stuck wide open, with the fuel level cycled (rich, lean, rich, lean, etc...) to keep it running.

So check for leaks, but also check the iacv. Check for problems/debris in the bore.

Today for the past two days when i set the car at park, or come at a stop, it idles at 900 rpm with NO Surging at all. This was really strange, but leaks still could be a possibility.

xci.ed6 said:

The surging is ussually the iacv stuck wide open, with the fuel level cycled (rich, lean, rich, lean, etc...) to keep it running.

So check for leaks, but also check the iacv. Check for problems/debris in the bore.

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Brand new IACV, cant be surging from that, maybe the computer is going nuts about it

irtiza18 said:

James i wish you were my mechanic, youve been giving me help here n there lol, the replacement was brand new $85 good quality one, it seems as thou the car already got used to its new IACV after two weeks

It jsut didnt sound right either about reprogramming the computer, i will have to check for bad conenctions or a possible vaccum leak.

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Haha! Thanks! Did you change the gasket on the IAC too? I distinctly remember ripping mine when I removed my valve once too...

If you want to check that all your vacuum lines are okay, you can go buy an assortment of vacuum caps and install them on the intake manifold. Go one by one, see if there is one that makes a difference though there is one thing that is apparent. If you have a vacuum leak, its a large one. So you're probably looking at a tear in the brake booster line or something along those lines to get the problem you are having.

james'99 said:

Haha! Thanks! Did you change the gasket on the IAC too? I distinctly remember ripping mine when I removed my valve once too...

If you want to check that all your vacuum lines are okay, you can go buy an assortment of vacuum caps and install them on the intake manifold. Go one by one, see if there is one that makes a difference though there is one thing that is apparent. If you have a vacuum leak, its a large one. So you're probably looking at a tear in the brake booster line or something along those lines to get the problem you are having.

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Yes i changed the gasket on the new IACV with the new gasket provided, hey now that you mentioned about the brake booster line here's my observations from today.

Im in park, car's idling at a 1000 rpm. and i just depressed the brake pedal a couple of times and the rpm was rising a bit and bam! there starts the idle surging, so its making me really curious. When i come to a stop, the rpm gauge would also jump like a slight rpm right at the stop if you know what im talking about. I'm really hoping we're getting close to this problem, im hoping its somewhere in the brake booster/lines

When it happens because you press the brakes, booster. Not the lines.

xci.ed6 said:

When it happens because you press the brakes, booster. Not the lines.

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yea i know that i put a slash between it, before this code came on along with IACV problem, it would jump a slight rpm when i came to a stop, im thinking it has to do with the brake booster, booster lines, or maybe a vacuum leak.