Surging idle, before and after new IAC valve

**JacobLS1** · 03-12-2012, 06:26 PM

I have a surging problem, about every 3 seconds the car revs slightly. with the IAC unplugged, it stops. idles normal. replace the IAC valve today, and it still surges. i believe the TB had been polished. i cleaned the maf, TB, and IAC opening not too long ago. just surged a little faster.

There is a ticking coming from the intake, do not know if it is related or not.
http://imageshack.us/clip/my-videos/526/2x2w.mp4/

thanks.

**Knight** · 03-12-2012, 06:35 PM

Sounds like a vacuum leak possibly. Check all the vacuum hoses for cracks or even being disconnected. If you can't narrow it down, you can spray a little starting fluid around different areas, and when the idle raises, check that area.

**JacobLS1** · 03-12-2012, 06:42 PM

I've tried that before and nothing happened. so if there is one, its that small.

**Knight** · 03-12-2012, 06:47 PM

Another thing you might check is the wiring for the sensor. Make sure the connections are good, and none of the wiring is pinched, broken, or shorting/grounded.

**Deviant LS1** · 03-12-2012, 07:46 PM

Have you done the TPS and IAC reset? When I was cammed sometimes my car wouldn't grab an idle after I disconnected the battery. I would reset the TPS and IAC and the car would idle fine.

You unplug both the TPS and IAC. Key the car to the ON positiong. Don't start it. Wait 30 seconds, key off. Plug the sensors back in and start the car.

When you're adjusting the TB set screw to get your IAC counts into the right range you have to do this each time. Perhaps yours is slightly off and just needs to be relearned.

**35th-ANV-SS** · 03-12-2012, 08:05 PM

Another thing to consider is that new parts do not always equate to good parts.

**KMdef9** · 03-13-2012, 12:00 AM

Originally Posted by 35th-ANV-SS

Another thing to consider is that new parts do not always equate to good parts.

This, I got a new iac for my Jeep and it wouldn't bring the idle down, even after the reset it didn't work. Ended up with a different manufacturer to get it working normally.

**JacobLS1** · 03-13-2012, 02:59 PM

Tried resetting the iac and tps. Cleaned the iac port, and plug. Cant see any physical damage in the wires.

IAC counts??

**smokestack** · 03-13-2012, 03:26 PM

Originally Posted by JacobLS1

Tried resetting the iac and tps. Cleaned the iac port, and plug. Cant see any physical damage in the wires.

IAC counts??

Any handheld scanner? We need data lol

**JacobLS1** · 03-13-2012, 03:40 PM

Like a tech 2? No. I can probably use one at my brothers work. It set off a p0507.

What kind of info? so when I use the scanner.

Found this..I think its coolant. Rock hard..

**cammed goat** · 03-13-2012, 03:44 PM

I think that is epoxy. I have read some people use epoxy when they port/polish throttle bodies. I think the epoxy is used to fill the IAC hole and bypasses it.

**JacobLS1** · 03-13-2012, 04:45 PM

smelt like coolant.. maybe its the coolant line right under the throttle body. i took it out, in hopes of the IAC getting more air. its more quiet. almost seems more subtle. i also hooked the AIR hose back up, but i don't think it helped. no more noise from the AIR pump though.

**cammed goat** · 03-13-2012, 04:52 PM

Was the AIR hose ever disconnected before?

**JacobLS1** · 03-13-2012, 06:01 PM

Ever since I bought it. EGR was removed. Assumed the AIR pump was as well. Bought it two years ago. Problem started last october.

Neglected to mention. Its only when the engine is warm.

**JacobLS1** · 03-15-2012, 12:49 PM

Covered the hole in the throttle body, no more surging. The idle still hangs at 1500 in neutral. Few steps closer atleast.

**cammed goat** · 03-15-2012, 04:32 PM

Just checked over the net. When was the last time you checked your PCV?

**JacobLS1** · 03-15-2012, 05:10 PM

Never. Just see if its clogged?

Pass. side, adjacent to the tb? I don't see anything...Its an ls6 intake, egr was removed. don't know where the occur would be relocated to. There is something running alongside the intake(pass side)

**JayTA98** · 03-15-2012, 06:35 PM

make sure the whole hose/pipe that comes out on the left side of the TB is intact. In that tubing is the PCV. I will check that the PCV is moving free, inspect the rubber pieces where it connect to. Check the whole tubing that goes around the back of the intake. There is a rubber Y behind the intake that roots and causes a vaccum leak. Check the elbow that goes to the drivers side valve cover as well. there is a few pieces of plastic that meltdown if are not in the right place and cause a leak too.

**JacobLS1** · 03-15-2012, 06:41 PM

Originally Posted by JayTA98:2756659

make sure the whole hose/pipe that comes out on the left side of the TB is intact. In that tubing is the PCV. I will check that the PCV is moving free, inspect the rubber pieces where it connect to. Check the whole tubing that goes around the back of the intake. There is a rubber Y behind the intake that roots and causes a vaccum leak. Check the elbow that goes to the drivers side valve cover as well. there is a few pieces of plastic that meltdown if are not in the right place and cause a leak too.

So it's probably the bulge that's runs along the pass. side of the intake under the fuel rails. Ill check the whole hose in the morning. Kinda tempted to pull the intake to check the valley anyway.