Update:

Ok, car is running rough. It's idling at around 2K RPM. Sometimes, it'll bounce between ~1600-2000 RPM and sometimes, it'll drop to around 1100 RPM, but be idling roughly. At this point, it's pretty much misfiring and sounds like a lawn mower and drives like a$$. I checked for vacuum leaks by spraying throttle body cleaner around the hoses. No changes in idle.

Upon restarting, the RPMs are high again and the car drives normally.

Since the last update, I've changed the IACV with a new used one from ebay and replaced the neutral safety switch (new from Servco)

The car still pulls healthily when I get on the throttle, but the idling is horrible.

Still showing a P1507 code.

I have not yet adjusted the throttle position sensor (as some have found to be the fix) or changed out the front o2 sensor (have one, but have not installed yet).

*scratches head*

Have any of you adjusted your TPS? I do not have a multimeter to adjust it properly. Anybody with experience free today? LMK!

Thanks in advance.

 

You probably got a bad IACV from ebay. Reset your ECU, see if it comes back. If it does pull the IACV back off and make sure it rotates easily. The little gate should flip back and forth with zero resistance.

 

The IACV that went in was very clean and the little gate inside moves freely and smoothly.

 

is the IACV from ebay an OEM part?

my concern is the misfiring codes...diagnostic routines normally start you with the lowest codes and work your way up... P0300 P0301 P0302 P0303 P0304....though if you got the random misfire code...and you have no vacuum leaks might point you to a fuel problem...though i think your P1507 code is misleading you...only because of your random misfiring and the pcm trying to get a stable idle...run it for a while with the P1507 and see if the other codes pop up later....

do you leave you park your car outside the garage? is your fuel cap easily accessible? someone pour sugar down the tank?

 

The p0300-p0304 codes don't show up anymore, just the p1507 and the occasional p0507.

I'm kinda hoping more codes pop up if it helps narrow down the issue.

 

Did you clean the PCV? you know da-kine.

 

Yep.

 

Remove the IACV but leave it plugged in. Cover the IACV hole with a small plate and some sealant.

Let it dry. Adjust the limit screw for the throttle body flap as to allow only a small amount of air by.

Start the car. Adjust the limit screw to allow for proper idle speed.

If it stays steady and consistent the IACV or circuit is most likely still your problem.


Also clean the throttle body around the flap and make sure your throttle cable slides freely through the housing.

 

UPDATE: Fixed.


Capped off my PVC. Now runs smooth, strong, and idles quietly and smoothly at 500rpm.

I don't know why this works this way. When I bought my car, it was capped off then. When it was hooked up, the car would idle around 1,200-1,500rpm. It ran his way for the past year just fine until recently.

*shrugs*

 

if the valve is stuck open (allowing maximum airflow) this would cause the problem you had. just replace the valve since it's easy to get to and replace. it's supposed to restrict airflow at idle and open as the rpms increase. thats why your car ran ok after a certain rpm since under normal operation it would be open that much at a certain rpm/speed. when you keep a constant speed the valve is suppose to close (like boost dropping off when cruising on the freeway) so thats why it ran like crap when you kept a constant speed. i think it works off of vacuum so thats why it acts like a vacuum leak. anyways glad it's fixed.

 

I know it's not really on topic... But just found out my tgv sensor may be going... Lol anybody got a set if deleted tgv's???