Rough Idle? Video inside

[forcefed03]

My cobra runs great. Nice and smooth, no hesitation, just perfect. But after ~20 miles of stop and go traffic in the 98 degree az heat, the car idles funny. I can see the RPM bouncing. Though even though it idles like this, the car runs strong and sees no problems...

I have asked a local mustang shop about this, and they informed me that its just the muscle car way of idling, rough...

It has a Brand new 180amp alt
Voltage on the battery shows a solid ~14's
Fan was on - though i dont have a temp gauge, the stock temp was at normal operating temp.

I knows shes dirty :rolling:
Video: Its a bit tough to tell in the video, but if you listen closely to the engine bay, you can kind of hear it bouncing.

[youtube_browser]qKdXyXqgxfQ[/youtube_browser]

 

[crazycarlo]

try cleaning your IAC and your MAF.

 

[forcefed03]

Is there a way to clean the maf without taking the whole filter/CAi apart?

 

[SVT_Troy]

Are you thrwing any codes what soever? Had you checked for vacuum leaks?

 

[TVSCobra]

Unplug the IAC sensor (located on the throttle body/plenum) and see if that changes the rought idle at all.

 

[forcefed03]

Are you thrwing any codes what soever? Had you checked for vacuum leaks?

No codes, no leaks

Unplug the IAC sensor (located on the throttle body/plenum) and see if that changes the rought idle at all.

What should i anticipate for? what is the IAC sensors duty?

 

[TVSCobra]

No codes, no leaks


What should i anticipate for? what is the IAC sensors duty?

The IAC controls the idle speed. The PCM PWM (pulse width modulates) the IAC valve to regulate how much air bypasses the throttle body to regulate the idle speed.

Unplugging it will make the car idle really low or in some cases the car will shutdown, what I was looking for is to see if the idle gets smoother if you unplug the IAC while the car is running at idle.

You will have to clear any DTC after doing this.

 

[Jefe]

My cobra runs great. Nice and smooth, no hesitation, just perfect. But after ~20 miles of stop and go traffic in the 98 degree az heat, the car idles funny. I can see the RPM bouncing.

First off what shop told you that is normal? Thats not normal. I hope it was AMP

Bouncing how much? Sounds pretty consistent. Have you swapped out your thermostat or changed fluids? Mine did exactly that after I thought I burped the cooling system properly. My rpms would bounce from 500-900 every second. Burped it again with the nose in the air and I never had that problem again