running rich? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

ibanezxguy · 05-28-2002, 11:37 PM

I believe im running rich... i have a nice black carbon build up in my exhaust pipe and im sure its coated my whole exhaust system valves and all. But is this a sign of running too rich?  I also get little puffs of smoke when i take off.  Im dont seem to be burning oil or anything like that.  But if i am running rich how do i make her run a little leaner?

S13Grl · 05-29-2002, 01:35 AM

*Belongs in Tech*

-----------------

If you believe you are running too rich, you should be able to notice the "richness" in your gas mileage. Figure out how many MPGs you get, but still smell around your engine bay and look around on your intake manifold. If it reeks of gasoline, you may be running rich.

Your problem might be:

a) a defective fuel pump
b) a mistake in the ECU
c) you may have a clogged air filter or a dirty air filter which would cause you to run richer (less air, same fuel) or your throttle valve might not be functioning properly...

What year is your car?

Any mods?

ibanezxguy · 05-29-2002, 08:35 AM

its a 95 with just exhaust the intake will be here in 4 days. Its 2.5 if that makes a difference.  What mileage should i be getting?  I got 220 miles to the last tank on 93 octane.

Broadwayblues · 05-29-2002, 04:21 PM

I was getting mileage like that and smelled gas real bad, smoke stains on my bumper and kinda sluggish performance. Now I do have a 92 but I get 320 on a full tank of 86 octane.(whatever the cheap stuff is.) All I did was replace the O2 sensor. I bought it from Autozone and it made a whole new car. I would check the air filter first and if that doesnt get it then get the o2 sensor, put it on and disconnect the battery for 15 minutes to reset the ECU.(Or find out the other ways a couple of pages back) It's only $30 and you might need it soon anyway... I hope that helps.

BlackFox · 05-29-2002, 06:59 PM

I can smell gas in my engine bay... so a dirty air filter can cause this? I was not aware of that <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/lookaround.gif" border="0" valign="absmiddle" alt=':look:'>

DuffMan · 05-29-2002, 07:09 PM

Those puffs of white smoke mean you probably are running rich. See if you have any codes stored in the ecu, and check the O2 sensor.

geeaj · 05-30-2002, 10:32 AM

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Those puffs of white smoke mean you probably are running rich. See if you have any codes stored in the ecu, and check the O2 sensor.</td></tr></table><span id='postcolor'>

Since when does white smoke constitute a rich combustion scenario? I think your talking about a head gasket scenario. It is usually the black or dark greyish smoke accompanied by a "gasoline" smell around the engine bay/exhaust piping. The black soot forming on the tailpipe is valid as well

You are on the right track about the O2 sensor, but bear in mind that on 240, richness can be caused by other sensor failures as well.

Common problem is the engine temp sensor going bad, which causes the ecu to compensate and run in fail safe mode - ecu signal adjusts to run richer to prevent lean condition/detonation.

The other would be the MAF circuit going bad. Usually the ecu will throw a code indicating the circuit which is bad. Sometimes, a faulty ECU maybe the problem. This doesn't happen too often. There is a FAQ on checking the ECU codes, check it out and do the diagnostic.

When was the last time you cleaned out your throttle body? Lost of shit can build up in there and cause airflow issues, leading to rich conditions as well.

DuffMan · 05-30-2002, 01:22 PM

Yeah, black smoke usually means running rich, but i have seen little puffs from my car like he explained, when running rich. It's unburt fuel vapaors that are in the exhaust that get pushed out when you accelerate.

To help you diagnose it, a bad engine temp sensor will usually cause the engine to never idle below 1500 rpms. If it does that, I would check that first.

*sykikchimp* · 05-30-2002, 01:59 PM

just a note, but the stock 240 ecu has a tip-in-retard function built in that retards timing slightly when you go WOT.  This causes a rich condition (rich is safe).  This can sometimes cause the mysterious puff of smoke on a hard take off.

05-29-2002, 04:21 PM	#4
Broadwayblues Zilvia Member Join Date: Apr 2002 Posts: 193 Trader Rating: (0) Feedback Score: 0 reviews	I was getting mileage like that and smelled gas real bad, smoke stains on my bumper and kinda sluggish performance. Now I do have a 92 but I get 320 on a full tank of 86 octane.(whatever the cheap stuff is.) All I did was replace the O2 sensor. I bought it from Autozone and it made a whole new car. I would check the air filter first and if that doesnt get it then get the o2 sensor, put it on and disconnect the battery for 15 minutes to reset the ECU.(Or find out the other ways a couple of pages back) It's only $30 and you might need it soon anyway... I hope that helps. __________________ "stop lights timed to 55 mph are also timed to 110 mph!" http://www.geocities.com/broadwayblues34/240sx.html 92 240SX Coupe! MB clear side markers Clear bumper lights 3 inch universal muffler w/ removable tip. Strut tower bar- Front OBX SS version 2

05-29-2002, 06:59 PM	#5
BlackFox Zilvia Junkie Join Date: Feb 2002 Location: San Jose, CA Posts: 534 Trader Rating: (0) Feedback Score: 0 reviews	I can smell gas in my engine bay... so a dirty air filter can cause this? I was not aware of that <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/lookaround.gif" border="0" valign="absmiddle" alt=':look:'> __________________ Current Cars: 1976 Mercedes Benz 300D 1995 240sx SE aka Kate (winner: Best Stock S14 @ 2002 National Convention) http://community.webshots.com/user/jeff976cal If you're interested in parts email me [email protected]

05-30-2002, 10:32 AM	#7
geeaj Zilvia Junkie Join Date: Dec 2001 Posts: 357 Trader Rating: (0) Feedback Score: 0 reviews	</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Those puffs of white smoke mean you probably are running rich. See if you have any codes stored in the ecu, and check the O2 sensor.</td></tr></table><span id='postcolor'> Since when does white smoke constitute a rich combustion scenario? I think your talking about a head gasket scenario. It is usually the black or dark greyish smoke accompanied by a "gasoline" smell around the engine bay/exhaust piping. The black soot forming on the tailpipe is valid as well You are on the right track about the O2 sensor, but bear in mind that on 240, richness can be caused by other sensor failures as well. Common problem is the engine temp sensor going bad, which causes the ecu to compensate and run in fail safe mode - ecu signal adjusts to run richer to prevent lean condition/detonation. The other would be the MAF circuit going bad. Usually the ecu will throw a code indicating the circuit which is bad. Sometimes, a faulty ECU maybe the problem. This doesn't happen too often. There is a FAQ on checking the ECU codes, check it out and do the diagnostic. When was the last time you cleaned out your throttle body? Lost of shit can build up in there and cause airflow issues, leading to rich conditions as well. __________________ Beware the fury of a silent man, be more cautious of his silent farts....

05-30-2002, 01:59 PM	#9
sykikchimp WOW addicted Join Date: Dec 2001 Location: the moon Age: 44 Posts: 6,525 Trader Rating: (0) Feedback Score: 0 reviews	just a note, but the stock 240 ecu has a tip-in-retard function built in that retards timing slightly when you go WOT.  This causes a rich condition (rich is safe).  This can sometimes cause the mysterious puff of smoke on a hard take off. __________________

05-28-2002, 11:37 PM	#1
ibanezxguy Zilvia Member Join Date: May 2002 Location: Augusta,Ga Posts: 176 Trader Rating: (0) Feedback Score: 0 reviews	I believe im running rich... i have a nice black carbon build up in my exhaust pipe and im sure its coated my whole exhaust system valves and all. But is this a sign of running too rich?  I also get little puffs of smoke when i take off.  Im dont seem to be burning oil or anything like that.  But if i am running rich how do i make her run a little leaner?

05-29-2002, 01:35 AM	#2
S13Grl Married to the Mob Join Date: Dec 2000 Age: 44 Posts: 3,670 Trader Rating: (0) Feedback Score: 0 reviews	Belongs in Tech ----------------- If you believe you are running too rich, you should be able to notice the "richness" in your gas mileage. Figure out how many MPGs you get, but still smell around your engine bay and look around on your intake manifold. If it reeks of gasoline, you may be running rich. Your problem might be: a) a defective fuel pump b) a mistake in the ECU c) you may have a clogged air filter or a dirty air filter which would cause you to run richer (less air, same fuel) or your throttle valve might not be functioning properly... What year is your car? Any mods?

05-29-2002, 08:35 AM	#3
ibanezxguy Zilvia Member Join Date: May 2002 Location: Augusta,Ga Posts: 176 Trader Rating: (0) Feedback Score: 0 reviews	its a 95 with just exhaust the intake will be here in 4 days. Its 2.5 if that makes a difference.  What mileage should i be getting?  I got 220 miles to the last tank on 93 octane.

05-29-2002, 07:09 PM	#6
DuffMan Post Whore! Join Date: Oct 2001 Location: in a cardboard box Posts: 2,517 Trader Rating: (0) Feedback Score: 0 reviews	Those puffs of white smoke mean you probably are running rich. See if you have any codes stored in the ecu, and check the O2 sensor.

05-30-2002, 01:22 PM	#8
DuffMan Post Whore! Join Date: Oct 2001 Location: in a cardboard box Posts: 2,517 Trader Rating: (0) Feedback Score: 0 reviews	Yeah, black smoke usually means running rich, but i have seen little puffs from my car like he explained, when running rich. It's unburt fuel vapaors that are in the exhaust that get pushed out when you accelerate. To help you diagnose it, a bad engine temp sensor will usually cause the engine to never idle below 1500 rpms. If it does that, I would check that first.