Catalytic Converts

[CUAviator]

Looks like I’m going the Catalytic converter route to try and tamp down on the gas smell so that I can use this car as a daily driver and a date car (wife won’t drive with me anymore).

302
EFI
Borla x-pipe
24# injectors

priority 1 - reduce gas smell
Priority 2 - minimize reduction in performance

does anyone have any recommendations for catalytic converters?

 

[B67FSTB]

IMHO gas smell won't go away with catalic converters.
How is your exhaust routed ??
Does your exhaust has any leaks ? For sure ??
While driving you shouldn't have any gas smell , even without catalic converters.
my 2 eurocent.

 

[Starfury]

Wasn't this a previous topic?

Cats are not meant to go on just any vehicle. They have specific requirements for A/F ratio, specifically in varying the A/F ratio under cruise conditions. You can't just shove them on something running too rich and expect them to make everything better.

As stated above, if things are properly tuned, you shouldn't have a gas smell while driving.

 

[gsxrken]

Agreed with the above posters. You should probably install an air fuel ratio gauge or at least temporarily hook up one like the LM1 I have and dial in your AFR across various rpm and throttle points. Gas smell during cool off in the garage might be helped by a phenolic spacer under the curb to insulate it from boiling off the gas in the fuel bowls.

 

[kb3]

I am surprised there are any gas fumes as well. He is running Ford SEFI, so there is no carb or open gas to smell. Adjusting the air/fuel ratio is tough to do as well considering the Ford computer should be doing that. I would tend to think there is a problem with an O2 sensor that could be causing ratio to be off.

 

[JeffTepper]

In my experience that the focus should be on the many "holes" in the car that need to be plugged up. Start with the sheet metal. Trunk floors and quarter panels have any holes? How about the firewall? Weatherstrips need replacing? When the body is sealed up completely, look at the fuel system components. Is the top of the gas tank rusty? Is the gas cap seal shot? Are any of the fuel hoses and lines seeping or leaking?

 

[B67FSTB]

I am surprised there are any gas fumes as well. He is running Ford SEFI, so there is no carb or open gas to smell. Adjusting the air/fuel ratio is tough to do as well considering the Ford computer should be doing that. I would tend to think there is a problem with an O2 sensor that could be causing ratio to be off.

If so (sefi) , I'll second that.

 

[CUAviator]

In my experience that the focus should be on the many "holes" in the car that need to be plugged up. Start with the sheet metal. Trunk floors and quarter panels have any holes? How about the firewall? Weatherstrips need replacing? When the body is sealed up completely, look at the fuel system components. Is the top of the gas tank rusty? Is the gas cap seal shot? Are any of the fuel hoses and lines seeping or leaking?

Copy all that info...is any classic mustang sealed completely. As for some of the other questions - it’s. New gas tank. Cap seal isn’t bad. It’s been checked for leaks - fuel and exhaust.
when the engine is running, there is absolutely NO smell anywhere UNTIL you walk around the back and get absolutely BLASTED with gasoline (not exhaust) smell - your eyes water and your lungs burn, and then you wreak of that all day. When the car is off, the exhaust tips smell like raw gas.

 

[CUAviator]

Wasn't this a previous topic?

Cats are not meant to go on just any vehicle. They have specific requirements for A/F ratio, specifically in varying the A/F ratio under cruise conditions. You can't just shove them on something running too rich and expect them to make everything better.

As stated above, if things are properly tuned, you shouldn't have a gas smell while driving.

From what I can tell, the Fox body 5.0s have cats, and that’s what with engine is. Why would they not belong on the car?

 

[Aussie67]

A few of us in Oz have fitted these and they have made a huge difference. However we are all running carbs. Despite peoples thoughts, the cats aren't restrictive.

If you're running EFI and have an OEM ECU, I would use the OEM cats for the motor as you should probably run the oxy sensors as well. The ones in the link don't have any provision for the oxy sensors.

Classic Car Catalytic Converter | Redback Converters

US Patent Approved. (US 10,605,139 B2) This is the first time in the company ́s history that we have designed a catalytic converter for the classic car market.

www.redbackconverters.com

DEA (Europe) and Magnaflow do one to.

 

[gsxrken]

Sorry I posted about a carb when your original post mentions EFI. I’m sure you have an O2 sensor in that regard.
don’t mind me. Duh

 

[CUAviator]

Sorry I posted about a carb when your original post mentions EFI. I’m sure you have an O2 sensor in that regard.
don’t mind me. Duh

Haha. I would assuming nothing about his particular vehicle. Frankenstein ain’t got nothin on my mustang!

 

[Starfury]

From what I can tell, the Fox body 5.0s have cats, and that’s what with engine is. Why would they not belong on the car?

Sorry, I missed the EFI note in the original post.

As others have said, if it's factory SEFI, something is up. Strong gas smell means unburned fuel. A properly running engine will burn most of the fuel.

Some things that can cause unburned fuel:
Lopey cam
Bad O2 sensor
Exhaust leaks
Vacuum leaks
Incorrect fuel rail pressure

Even on an EFI system, shoving cats on an engine running too rich will simply ruin the cats. Fix the problem, not the symptom.

 

[B67FSTB]

"Fix the problem, not the symptom. "
+1

 

[Horseplay]

Start with the basics and make sure your engine is tuned and running properly. Just because it starts and drives doesn't mean it is. Verify the O2 sensor function AND location. An improperly placed but functioning sensor can cause it to run rich. I love the idea of incorporating an A/F gauge. It doesn't have to be a permanent fixture just use it to aid in tuning.

Have you pulled the plugs and "read" them to see how things are going? Be interesting to see pics of them. They can typically tell you the story of where you are at better than anything else.

All that said, some engines are going to be less effective at burning fuel than others. As mentioned earlier, if you've got a pretty aggressive cam featuring lots of overlap...get used to unburned fuel. I think in this case a pair of cats might help initially but they are going to get used up quickly with all that raw fuel coming into them consistently.

This wouldn't even be an issue if they went back to making the gas of yesteryear. That stuff smelled awesome!

 

[B67FSTB]

This wouldn't even be an issue if they went back to making the gas of yesteryear. That stuff smelled awesome!

Where is the time ???

 

[CUAviator]

Thanks all for the inputs. I’ll look into all that stuff. i guess my frustration comes from it having been looked at by a few shops, everyone saying it’s good, no problems, “that’s just what it smells like”. I’ve got the standard E303 cam...nothing too aggressive.

 

[Starfury]

What is idle rpm? That cam has a fair amount of valve overlap and is not going to like idling low, and will absolutely spit unburned fuel out the pipes at low idle.

I'd expect idle rpm of 800-900 to help smooth out the idle. On a carbureted car, you could run manifold vacuum to the vacuum advance, but that won't help in your situation.

 

[CUAviator]

What is idle rpm? That cam has a fair amount of valve overlap and is not going to like idling low, and will absolutely spit unburned fuel out the pipes at low idle.

I'd expect idle rpm of 800-900 to help smooth out the idle. On a carbureted car, you could run manifold vacuum to the vacuum advance, but that won't help in your situation.

Excellent point. That was just pointed out to me by a work colleague yesterday - it’s 500-600. I will he adjusting that this weekend.

 

[Starfury]

Yup, crank it up, particularly if you have an automatic.