Exhaust Smells Rich, Problem??

9

90GTSilverStang

New Member

Nov 2, 2006

15

0

0

Dec 2, 2006

#1

• Dec 2, 2006

• #1

The car is a 90gt vert Basically stock except for off road H pipe, shorty headers, flowmaster catbacks. I don't have cats. No check engine light. The exhaust smells like its running real rich. could it be I need a adjustable fuel pressure regulator to lower the fuel pressure? Anyone with the same problem? Engine runs well.

 

BlownFiveLiter

have car, will race....wait, it doesn't run

15 Year Member

Nov 29, 1999

3,133

18

108

Chicagoland

Dec 2, 2006

#2

• Dec 2, 2006

• #2

No cats means your HC (hydrocarbons=unburned gas) will be higher, hence the smelling rich. If you're really concerned, you could pull codes, but 99% of the time, it's going to smell rich after removing the cats.

 

onefstsnake

New Member

Nov 25, 2005

792

1

0

Northern VA

Dec 2, 2006

#3

• Dec 2, 2006

• #3

yeah mine runs a little richer now that I have an O/R H on mine.

The bumper gets dirty real quick too...

Its not going to hurt anything but gas mileage...

My A/F at 5K rpm was 11.9 : 1 lol

 

9

90GTSilverStang

New Member

Nov 2, 2006

15

0

0

Dec 2, 2006

#4

• Dec 2, 2006

• #4

what is considered a good A/F Ratio? Through 6k RPM's.

 

O

OrLackThereof

New Member

Mar 9, 2003

560

0

0

Palm Bay, FL

Dec 2, 2006

#5

• Dec 2, 2006

• #5

11.9:1 is too rich for an N/A app. I'd look for the high-end of 12:1. I run about 12.9:1 WOT, NA with heads cam etc.

 

onefstsnake

New Member

Nov 25, 2005

792

1

0

Northern VA

Dec 2, 2006

#6

• Dec 2, 2006

• #6

my shop told me that most 5.0's run rich w/o tuning.
probably just something ford did to get the engines to last a little longer and avoid detonation.

I wouldnt touch the FP regulator till you get it on a dyno.

but like I said, running rich is only gunna hurt your gas mileage.

 

MUSTANGJOE

Silver Stanger

Founding Member

Apr 9, 2002

1,644

17

59

Dec 2, 2006

#7

• Dec 2, 2006

• #7

Mine smelled like it was running rich after I installed my h-pipe. Actually every car that has an off road H smells rich!

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

34

129

Dec 3, 2006

#8

• Dec 3, 2006

• #8

I agree - even a car with spot-on stoichiometry tends to smell stinky with no cats. Our noses aren't all that accurate for determining A/F ratios.

Good luck.

 

jrichker

StangNet's favorite TOOL

In Remembrance. Thank you for your contributions

Mar 10, 2000

27,512

2,813

234

Dublin GA

Dec 3, 2006

#9

• Dec 3, 2006

• #9

Your O2 sensors may be on the old side.

Dump the codes and see what the computer says is wrong…Codes may be present in the computer even if the Check Engine light isn’t on.

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $35.

 

onefstsnake

New Member

Nov 25, 2005

792

1

0

Northern VA

Dec 3, 2006

#10

• Dec 3, 2006

• #10

My O2 sensors were new when I changed the Hpipe.

 

O

OrLackThereof

New Member

Mar 9, 2003

560

0

0

Palm Bay, FL

Dec 3, 2006

#11

• Dec 3, 2006

• #11

My A/F is spot-on, and I run a catless X pipe and dumps, and my car hardly smells at all. Believe me or not, but I dialed my A/F in by ear, nose, and seat of pants...kept adding/removing fuel in 0.5 psi increments and driving it, until it didnt stink and felt not....sloppy....but not jagged either. Hard to put into words, but you can feel the motor through the gas pedal...if you tip in and it feels harsh or rough, it's lean...if it feels squishy and soft, it's rich. Doing that, I got it on a wideband after and A/F was 12.9:1.

Im not saying everybody can do it, and it takes a lot of time and plug-reading and whatnot, but it'll save ya some money. Hell how do you think they did it before widebands?

 

9

90GTSilverStang

New Member

Nov 2, 2006

15

0

0

Dec 3, 2006

#12

• Dec 3, 2006

• #12

Hissin50, I've read a few of your posts and I am not going to change the FPR. One of your post read that if you lower the fuel pressure the computer makes up for it by widening the pulse width to the injectors and effectively nothing has really changed. So I will first check the codes. But-- How does one dial in the A/F ratio to tune it in? I read about the Tweecer but what is it?

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

34

129

Dec 3, 2006

#13

• Dec 3, 2006

• #13

For your situation, I'd tend to agree that an AFPR is not going to help (there are times when it can indeed help).

You hit the nail on the head - you'd need a handheld (TwEECer, PMS, etc), chip, stand-alone system, or other device to tune the AF ratio. For most-all except the chip route, you'd need a wideband to see what's going on. A laptop helps in many cases as well.

I'd note that this is all just a little overboard for a mild bolt-on car. Installing some nice high-flow aftermarket cats would likely cut down on the eye wattering/fuel stink. If things were getting out of kilter and truely too rich, the puter would try to lean the system down and you'd see adaptive limit codes (hitting the lean adaptive limit; system rich).

Random thoughts.

Good luck.