• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

stink butt

  • Thread starter Thread starter Butterfinger
  • Start date Start date Dec 29, 2010

Butterfinger

Member
Aug 11, 2006
74
1
8
Washington
Dec 29, 2010
#1
  • Dec 29, 2010
  • #1
I had an 89' without cats on it and it smelled bad of fuel from behind (engine was not buring any oil), do all Mustangs without cats stink or was it just that car? (everything else on the engine was stock)
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,157
17,849
224
Massachusetts
Dec 29, 2010
#2
  • Dec 29, 2010
  • #2
Pretty much every mustang i've been around without cats smells from the exhaust.

Kinda why i run cats
 

LarsD

Founding Member
Jul 2, 2002
2,680
119
123
Texas
Dec 29, 2010
#3
  • Dec 29, 2010
  • #3
Unless you are running rich, that's what a hot rod smells like.
 

dagenham

Member
May 23, 2010
100
3
19
Duncannon PA
Dec 31, 2010
#4
  • Dec 31, 2010
  • #4
I cant say that I have ever noticed any smell from the back of the wife's car and it doesnt have cats.
 

Butterfinger

Member
Aug 11, 2006
74
1
8
Washington
Jan 3, 2011
#5
  • Jan 3, 2011
  • #5
So the smell comes from a bad tune and no cats? The two O2 sensors are before the pre cats, so I don't see how the EEC-IV would ever know if the cats were removed, so where does the bad smell of gas come from?
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,157
17,849
224
Massachusetts
Jan 3, 2011
#6
  • Jan 3, 2011
  • #6
What you are smelling is unbunrt hydrocarbons which smell like raw fuel. It's not an indicator of poor tune.

The cat converters use various compounds to turn hydrocarbons, co and nox into co2 and water vapor.

Eliminate the cats, and instead of neutral smelling co2 and water vapor coming out of the exhaust, you smell hydrocarbons.
 

striker911

Member
Aug 6, 2008
156
1
18
Mountain Home, AR
Jan 3, 2011
#7
  • Jan 3, 2011
  • #7
My car has not had cats for the 8 years I have had it. I remember when I first got it I helped a friend haul a grill and the hatch would not close. It was real smelly in the car and we had to keep the windows down. That was when it was stock like yours. It has a lot of upgrades now and is still that way. If I pull up next to a car that has the windows down they end up rolling them up lol. Honest I hate it.

I like loud cars though and if I put cats on it I am sure to hate it. Had a leak fixed in the system and that alone made it a lot more quieter. I miss the hole in the pipe. I wonder what it would sound like with no mufflers and some high flow cats? Anyone ever hear that set up? I have some old flow masters (10 years +) as of now.
 

stykthyn

I want to measure mine. It doesn't look that tall.
15 Year Member
Jul 6, 2006
5,232
2,652
223
gainesville
Jan 4, 2011
#8
  • Jan 4, 2011
  • #8
Run that set up on my truck. Its loud.
 
You must log in or register to reply here.

Similar threads

B
Engine Another no start after washing engine bay
  • bruno
  • Apr 26, 2026
  • Fox 5.0 Mustang Tech
  • 2
Replies
24
Views
482
Fox 5.0 Mustang Tech May 7, 2026
AeroCoupe
2
Running very very rich
  • 2esoteric
  • Oct 31, 2025
  • Fox 5.0 Mustang Tech
Replies
4
Views
303
Fox 5.0 Mustang Tech Oct 31, 2025
Noobz347
Engine 87 NA - Tune or no Tune needed?
  • R82148V
  • Sep 17, 2025
  • Fox 5.0 Mustang Tech
Replies
8
Views
313
Fox 5.0 Mustang Tech Sep 17, 2025
R82148V
Resolved Three way cat converters..?
  • PonyGTrider
  • Nov 2, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
7
Views
236
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Nov 2, 2025
PonyGTrider
Engine Suggestions on an engine rebuild. Stock cam/GT40Ps or aftermarket on both for a fun weekend driver?
  • MadSquirrelTech
  • Apr 28, 2026
  • Fox 5.0 Mustang Tech
  • 2
Replies
23
Views
577
Fox 5.0 Mustang Tech May 7, 2026
MadSquirrelTech
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 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?