Fuel Mixture adjustment?

I have a '96 SL-1 with 100K miles on it. The exhaust system was replaced about 2 weeks ago and I noticed on the tailpipe alot of black residue (carbon). Obviously the engine is running rich. How do I adjust this? Thanks, Buster

Reply to
Buster
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Fuel mixture is controlled by the PCM and there is no user adjustment provided to change it. There are several things that may cause it to feel it needs to run rich. Have you had the codes read recently? That would tell you if any pertinent sensors (intake temp, oxygen, engine temp) need replacement or if any other problems exist. Has the car been getting worse mileage? Also, if the dealer plugs into the car, he can see mixture over time as well as real-time and confirm.

FYI, my tailpipes on my Saturns are always black. I'd tend to think that's normal since I read my codes frequently and know everything is operating as expected.

Lane [ l a n e @ p a i r . c o m ]

Reply to
Lane

Yeah, I have a rolled, stainless exhaust tip that, and with a paper towel, I wipe out the soot at car wash time. I didn't notice it as much with the old OEM pipe.

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Reply to
Jonnie Santos

You replace the Oxygen Sensor. If you have 100k miles on it, it's probably past time.

Reply to
Kirk Kohnen

I wouldn't replace a part like that just because........ My O2 sensor has more than 200k miles on it.

The black soot in the tailpipe is a common thing to every saturn I've seen.

Reply to
BANDIT2941

Both my Saturns (SL-1's) have this also and started consuming oil around 80K miles. I suspect that the valve guide seals may be the cause. Check your spark plugs to see if they show signs of excess oil being consumed.

Reply to
ShootnStraight

Reply to
Buster

Hi, Have had the service engine light on for a week now ( on and off, mostly on) on the saturn SL2 96 ( 86K miles). Mileage dropped significantly and there is lot of carbon on the tailpipe. Paid $50 to a mechanic to learn that the computer generated a 1406 code. He blames the problem on the use of low-garde gas. He is charging $400 to replace the component. Does code 1406 mean EGR valve is malfunctioning and needs to be replaced? Any advice would be apprecited. thanks- Saturn_96

Reply to
saturn_96

I searched Google for 'code 1406' and this came up. Maybe not directly applicable but interesting.

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Reply to
Oppie

Try to clean EGR valve with carburetor cleaner using an old toothbrush to remove the carbon. It is simple job that takes about 30 minutes. You also need to get new EGR valve gasket. I hope this will help. Michal

Reply to
Michal

I have a sturn 94 SL1. Had similar problemm. My gas milieage was extremely poor. Turns out it was my air temmperature sensor that wass baddd therefor sending too much gas in the combustion chamber. Once changed this was imeediately resolved. Might want to check this out. There was also no codes given out by the car's system.. That's why I was so surprised to know what was causing it. Hope this helps a little.

Reply to
Larry

Reply to
Buster

The O2 sensors arent read until the car enters closed loop. If its cold, it aint looking at it.

Reply to
Blah blah

Ok, I guess that's $100 I don't have to spend right away. Any other ideas on what could be causing this? My fuel consumption is off a little, and I notice pinging under light accelleration (step on the gas and the pinging quits). The pinging is an intermittent problem. Car has 105k miles on it. Thanks, Buster

p.s. What exactly does 'closed lo>>> I have a '96 SL-1 with the same problem. Last year I got a 1406 code

Reply to
Buster

Closed loop/open loop...It means the engine is either looking at all your sensors to adjust itself or running from a default computer setting for the current environmental conditions. O2 sensors and cat converters dont work when their cold.

Pinging can be carbon, bad knock sensor, poor fuel or fuel delivery, or a number of other things. It may ping when its cold but when it warms up it should go away right? Dont try to correct this by going to a higher octane gas. Thats a costly bandage to only fix a "symtom".

Reply to
Blah blah

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user

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