Rich, Lean what does it Mean

StangClear · Jan 21, 2004

Since I am not too swift in this area, are there any tell tale signs of these conditions? Or, how do you know? Someone explain what these terms mean, I have an idea but don't want to sound stupid. Thanks

JonJon · Jan 21, 2004

I'd like to know also... My friend told me he thinks I'm rich because when he was following me, I floored it a few times and he told me it smelled rich. He couldn't describe the smell though.

PoXiC · Jan 21, 2004

A car running rich is burning with more gas than air. The exhaust's fregrance is laced a little more with the smell of gasoline, but generaly isn't a bad thing unless it's extreme.

A lean condition occurs when a car burns more air than gas. This melts engine parts. It's exhaust fumes have a distinct smell that I can't realy convey over the internet. The only way to know is fist hand. When a car runs realy lean it feels like it burns your eyes to be near it.

jadesville · Jan 21, 2004

PoXiC said:
A car running rich is burning with more gas than air. The exhaust's fregrance is laced a little more with the smell of gasoline, but generaly isn't a bad thing unless it's extreme.

A lean condition occurs when a car burns more air than gas. This melts engine parts. It's exhaust fumes have a distinct smell that I can't realy convey over the internet. The only way to know is fist hand. When a car runs realy lean it feels like it burns your eyes to be near it.

lean = having a greater ammount of air in your optimal air to fuel ratio
rich = having a greater ammount of fuel in your optimal air to fuel ratio

DarkHorse164 · Jan 21, 2004

PoXiC said:
A car running rich is burning with more gas than air. The exhaust's fregrance is laced a little more with the smell of gasoline. A lean condition occurs when a car burns more air than gas. This melts engine parts. It's exhaust fumes have a distinct smell that I can't realy convey over the internet. The only way to know is fist hand. When a car runs realy lean it feels like it burns your eyes to be near it.

Good, easy way to describe the conditions.

StngStr · Jan 21, 2004

mine smells like gas. It only started smelling like that when I put my o/r X pipe in. I was thinking that it's just cause the cats aren't there to burn off the upburned gas. Is that true? I don't see why I would be running rich or lean, all i've done is the X pipe and welded in mufflers.

2013 Geee T · Jan 21, 2004

What is the proper A/F ratio for our cars supposed to be and what is too high and too low?

SVTSTEEDA · Jan 21, 2004

my friends always talk about how my car is so rich that they can't stand to drive behind me. so I go and get it dynoed and the car is extremely lean. how can this be?
it would puff some black smoke when it was LEAN and after the guy used a little trick to make it rich it did not smoke at all. am i just stupid. any thoughts? thanks.

sorry i'm not trying to hijack the thread i'm just trying to figure out the old saying "if the exhaust smells like gas then your are running rich".

JonJon · Jan 21, 2004

Also, if your car is rich, is it possible to experience a 4 MPG drop? I avg like 14 MPG after catted x and cat back. Used to be 17-18.

2001GTMILT · Jan 21, 2004

SVTSTEEDA said:
my friends always talk about how my car is so rich that they can't stand to drive behind me. so I go and get it dynoed and the car is extremely lean. how can this be?
it would puff some black smoke when it was LEAN and after the guy used a little trick to make it rich it did not smoke at all. am i just stupid. any thoughts? thanks.

sorry i'm not trying to hijack the thread i'm just trying to figure out the old saying "if the exhaust smells like gas then your are running rich".

What was his little trick??, how can we level out the A/F ratios???

jadesville · Jan 21, 2004

JonJon said:
Also, if your car is rich, is it possible to experience a 4 MPG drop? I avg like 14 MPG after catted x and cat back. Used to be 17-18.

yes..

JonJon · Jan 21, 2004

jadesville said:
yes..

I need to get dyno'd to see if that's really the problem. Got 13.9 MPG last fillup.

MotleyCrue · Jan 21, 2004

Maybe your right foot is to heavy JonJon

jadesville · Jan 21, 2004

MotleyCrue said:
Maybe your right foot is to heavy JonJon

nah, he drives like an old lady

JonJon · Jan 21, 2004

MotleyCrue said:
Maybe your right foot is to heavy JonJon

That's the funny thing, I get like 16 MPG when I drive like a maniac. Does that mean something?

jadesville said:
nah, he drives like an old lady

Only when you're in the car, you complain that I go too fast

StangLou · Jan 21, 2004

If you have to much gas going in, you can add bigger MAF or like a CAI, TB, anything in your air intake setup.
For either situation, a chip and a good tune on the dyno can fix both problems .

Blue 98 GT · Jan 21, 2004

seems to me that the computer should do the recalibration on a/f ratios. i think optimum is 10:1 or 11:1. Your front O2 sensors may need to be cleaned/replaced if its rich or lean. another thing thats always good to do is after you intall a new mod, run the car around for a day, then unplug the battery. this allows the computer to reset. when you reconnect the battery 30 mins later, it will redo all the calibrations. after an offroad x-pipe is installed, the exhaust will smell funny because a lot of the carbon monoxide is not converted to CO2. this gives it a sweeter smell. it will always smell like this because catalytic converters burn up excess fuel and convert CO to CO2.

Take your O2 sensors out (set closest to engine) and spray them down with Brakleen. this will clean all the carbon buildup out. if its still running rich/lean, you may need a retune on the MAF sensor or new O2 sensors.

SVTSTEEDA · Jan 21, 2004

2001GTMILT said:
What was his little trick??, how can we level out the A/F ratios???

He was told by a Vortech employee that you can mess with the FMU. My diaphragm or whatever was not lifting properly to release the fuel i guess. What he did was drill and "x" across the top of the FMU plate after he removed it from the car. This relieves the pressure. PLEASE do not try anything yourself without someone giving you BETTER info about this. I tried to understand what he did as I was there when he did it (takes 10 seconds) but do no want to hurt anyone's vehicle by giving bad advice or by explaining things completely wrong. After he did this my a/f ratio went down from around 14.5:1 to around 12:1. Basically a 2-2.5 point benefit across the board (it did drop the hp/tq of course)

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