• Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech

Strang problem w/ foot off gas...IAC?

  • Thread starter Thread starter vertigasen
  • Start date Start date Apr 16, 2010

vertigasen

Active Member
Apr 28, 2004
366
18
29
Falcon, CO
Apr 16, 2010
#1
  • Apr 16, 2010
  • #1
**EDIT** Well crap, apparently I can't type when I write STRANGE....

Ok, this problem just started over the last 2 weeks or so, but getting worse every day.

I'm driving along and remove my foot from the gas pedal. It is fine for a second then, a nasty droning sound. It is almost like an automatic that downshifted. Also, at the same time, my wideband goes to 30 then to the infinity symbol. I barely tap the gas...and it is back to normal, again, for only a second then back to what it was doing before. I drove on the interstate yesterday and it was horrid. If I got behind someone driving slow in the fast lane, right after I would let off the gas, @ 70 in 5th, the droning sound would start, the wideband would go off the charts.

Would the IAC cause this? I cleaned it when I did the KB install less than a year ago, but it still has about 93k miles on it. I know I need a new DPFE sensor since I put a small crack in it, but I sealed the crack. I am just trying to narrow this down because it is starting to tick me off.

Thx for the help
 

midnightdriver

Active Member
Jan 3, 2010
443
2
27
Northern California
Apr 17, 2010
#2
  • Apr 17, 2010
  • #2
vertigasen said:
**EDIT** Well crap, apparently I can't type when I write STRANGE....

Ok, this problem just started over the last 2 weeks or so, but getting worse every day.

I'm driving along and remove my foot from the gas pedal. It is fine for a second then, a nasty droning sound. It is almost like an automatic that downshifted. Also, at the same time, my wideband goes to 30 then to the infinity symbol. I barely tap the gas...and it is back to normal, again, for only a second then back to what it was doing before. I drove on the interstate yesterday and it was horrid. If I got behind someone driving slow in the fast lane, right after I would let off the gas, @ 70 in 5th, the droning sound would start, the wideband would go off the charts.

Would the IAC cause this? I cleaned it when I did the KB install less than a year ago, but it still has about 93k miles on it. I know I need a new DPFE sensor since I put a small crack in it, but I sealed the crack. I am just trying to narrow this down because it is starting to tick me off.

Thx for the help
Click to expand...

Well from what I have heard and from my own experience it sounds like your injectors are shutting off to conserve fuel. The sound you are hearing is the engine braking (Ie, the use of compression to slow the engine down). When the computer senses no throttle input and your engine is spinning more then idle rpm and is maintaining that rpm (or not dropping like a rock). Then the computer shuts the injectors off because you don't need them at the moment, but when you tab the gas and send a throttle input single the injectors re-fire making the noise go away until you let off again.

The wideband does not register or goes off the charts, lean I am guessing because there is no fuel burning in the combustion chambers (injectors not firing)

If you just installed the X pipe and gutted you cats, then the X pipe is breaking in and that is why the noise is getting louder.

If this is not a new X pipe, I would say your tune is out of wack or something computer related.
 

vertigasen

Active Member
Apr 28, 2004
366
18
29
Falcon, CO
Apr 18, 2010
#3
  • Apr 18, 2010
  • #3
Had my x-pipe for about 5 years, so that isnt it.....

I have also had this tune for over a year.....

Anything else I should look at?
 
You must log in or register to reply here.

Similar threads

Hard to start when engine is cold
  • 86_Capri
  • Mar 11, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
32
Views
972
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jun 21, 2026
CAMTWO1070
Engine Gas in my oil
  • limp
  • Jun 15, 2025
  • Fox 5.0 Mustang Tech
  • 2
Replies
35
Views
1K
Fox 5.0 Mustang Tech May 16, 2026
Mindseye007
SURGING IDLE / NO IDLE CHECKLIST FOR 1999–2004 MUSTANG GT (4.6L 2V) - Work In Progress
  • Noobz347
  • Aug 30, 2025
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
898
1996 - 2004 SN95 Mustang -General/Talk- Aug 30, 2025
Noobz347
SURGING IDLE / NO IDLE CHECKLIST FOR 1996–1998 MUSTANG GT (4.6L 2V) - Work In Progress
  • Noobz347
  • Aug 30, 2025
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
732
1996 - 2004 SN95 Mustang -General/Talk- Aug 30, 2025
Noobz347
K
TKX Transmission Shifting Problem
  • KWC156
  • Jun 23, 2025
  • Other Auto Tech
  • 2
Replies
21
Views
2K
Other Auto Tech Jun 13, 2026
427nostang
4
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?