HELP PLEASE! 95 maxima CEL P0507

[IMSQX4]

I bought a 95 maxima with 180k on it a few weeks ago. It was driving fine till a few days ago. I have very bad idle and the motor sounds really rough. I got the code P0507...so far I have:

-changed the plugs
-pcv
-cleaned the TB
-cleaned the Idle control
-cleaned the egr tube
-changed the leak valve cover gaskets and intake
-MAF looks fine

would anybody know what I need to replace?

Thanks

[MTZI30]

That code refers to the idle air control valve. I had a rough idle and replaced mine and it fixed it....

[IMSQX4]

Replace the idle control valve? are they known to go bad?

[MTZI30]

Well my car was idling rough, especailly when slownig to a stop, had CEL. Just had one of my techs look at it and he just replaced it. So your code COULD be something else but as far as i know its idle air control fault. I dunno if they're known to go bad but id say thats prolly your problem.

[loystock]

A faulty (shorted IACV can also 'kill' your ECM (driver/power transistor inside controller). Pull it out, check resistance of stepper motor coils 20-30 ohms (pins 2-1, 2-3, 5-4, 5-6). If Ok, clean the IACV and re-install. procedure is in the 'sticky' in this forum. You may have to use a new gasket. Also take note that there are other sensors that could IACV to be erratic

[IMSQX4]

Where is the ECM located? is it the same as the ECU?

what other sensors could cause the IACV to be erratic?

[loystock]

Check and clean your IACV first.

ECU and ECM refers to the same thing. For location, refer to page EC-12 while for Control signal/sensors associated with IACV, refer to page EC-123 from the link below

http://www.nicoclub.com/FSM/maxima/1995/ec.pdf

[IMSQX4]

I dunno if that's the problem now...its weird every time I check the CEL I get a different code. I'm starting to think
its probably the knock sensor? it usually causes faulty codes

[IMSQX4]

Replaced the KS today didn't work...now I'm getting code P0305!

this car is really pissing me off!

[loystock]

I don't know why you replaced the KS. A faulty KS will not even turn on the CEL (but trigger a fault code P0325). Have you checked the IACV and motor mounts? The ECM may be going bad. Maybe it's time to take your car to the dealer for a thorough diagnostics.

[IMSQX4]

I replaced it because it was cracked. It looks like I fixed the problem it was my #5 injector!