Car idling funky... :(

I installed a Densecharger tb pipe last Friday. I reset the battery (the gauges pegged after I turned the car on) and then let her idle for 5 minutes. Everything seemed fine. I drove to the drag strip (45 miles away) and about 5 miles from the drag strip I notice that when I came to a stop, the idle would bounce around and when shifting the revs hang. I got to the drag strip and reset my computer again since the car threw a SES... I checked connections to make sure everything was tight and hopefully no leaks and the SES was gone. I ran like crap at the track, no where near what I wanted to run. Not totally unexpected though with the 50 F weather, my driving, and my tires.

Anyways, I recorded 2 vids of the problem. These vid's are WITH the AC on, it wasn't idling funny last nite without the AC on. But today, it IS idling funny even without the AC. I reset the battery again yesterday morning and since, I've driven 60 miles. I recorded the vids after those 60 miles of driving.

You need the DivX decoder, I couldn't get an MPEG file small enough http://www.divx.com

I did NOT touch the gas pedal in either of these vids. The car just bounces around.
Odd idle 765KB

In this vid, I clutch in and the engine REVS up then idles down. I did NOT touch the gas pedal. I was coasting at 1800RPMs then clutched in and the car rev'd up to 2000 by itself. After another second or two it drops down to 700...
Hanging idle 140KB

Any idea's? Will it smooth out?? Another user had said his idle smoothed out after a few days of driving, but I wanted to post vids and get opinions. I figure 60 miles of driving should be enough for the computer to learn the new air flow but I guess not?

oh, I'm going to call DeMolet (Densecharger) on Monday and see what they say.
Car idled -perfect- with stock tb pipe. Even though I USED to have slight RPM drop when I came to an idle.

dkshadow said:

http://forums.stangnet.com/showpost.php?p=4051878&postcount=11

Click to expand...

Dyno on Saturday... but no tune.

My friend back home thinks it's a vacuum leak since he had the problem on his Cougar and his brother on his Talon.

Sound about right? It's getting dark now so I'll check tomorrow.

No one's had a vacuum leak in a 4.6?

DarkCheshire said:

Check and clean<----(maybe) your IAC (Idle Air Control) and anything that leads up to your intake. Mine did it a while ago and it was a cross of the cold air intake not being mounted secure enough to the frame and my IAC was a little dirty. So in short the car was thinking it was getting less/more air and was trying to idle to compensate.

Click to expand...

All I changed was the tb pipe though, the car was running and idling -perfect- with the stock pipe. Would that affect the IAC? Plus, the IAC was replaced this past summer... I just checked the MAF wires when I was checking for a vacuum leak, the MAF wires looked clean. The IAT sensor was aligned correctly and everything too.

20BlackGT02 said:

Does anyone know how to get these clips to work? Everytime I play the clips, my PC freezes and I have to restart. I would like to see how your car idles. What you are explaining sounds like the same thing that happens to my car since day one for the rpms to hang between gear shifts. I thought this was normal. And after both of my heads were replaced under warranty, the odd AC idle thing started to happen. When ever the AC kicks on for the defrost or air conditioner, the idle jumps up a hundred or two hundred rpms. I dont think this is normal. If it is, it's annoying.

Click to expand...

Sorry, I don't mean to crash your computer. The people I've sent the clips to have had no problem... It requires the DivX 5 codec from http://www.divx.com but it shouldn't cause crashes if you don't have it installed...


When I checked for a vacuum leak (I unplugged everything and replugged it all real tight) I let it run and it still idled funky... So I changed the idle screw a little (wider) and it seemed to have helped... My car is idling at 800rpms now (digital built in tac) and sometimes hangs at 1000 but so far it isn't doing that wild idle. I only got to drive it around for half an hour earlier so I don't know if the problem is going to come back again. I'm going to go drive around more tonight. I'll also try to turn the idle screw down a little so it doens't idle at 800...