what might be causing a rich condition? - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 03-30-2006, 08:37 PM   #1
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Default what might be causing a rich condition?

my sparkplugs r lookin pretty black, but i dunno why my car would run rich, if anything it should be lean what with my intake and the fact that i have a potential vaccum leak near my bcs, so what would normall cause it?
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Old 03-30-2006, 09:19 PM   #2
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Vacuum leaks can cause rich or lean conditions. There are other causes to be ruled out also, like fuel pressure, O2 sensor, coolant tempo sensor, thrmostat rating.... Fix what you know is wrong first, then check for codes. Take off the throttle body and inspect the egr inlet. It could be antifreeze is being sucked in too.
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Old 03-30-2006, 09:51 PM   #3
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Pop, he'* supercharged. We won't be prone to the same EGR stovepipe issues. That'* an L36 problem only. Not L67.

Nerv, a vacuum leak will typically run you lean. It'* unmetered air. Typical rich conditions are caused by tired O2 sensors (that'* the biggest cause in our cars). When was the last time you replaced yours?

A weak alternator can also cause a weak spark, preventing a complete burn. What'* your alternator doing these days? What kind of plugs? What kind of wires? Can you use Techinfo to check your coils?
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Old 03-30-2006, 11:05 PM   #4
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well i tihnk both my o2 sensor and alternator are original, what should the output of mt alternator be and how woul i test that? regular voltmeter?
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Old 03-30-2006, 11:11 PM   #5
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A scantool would show you alternator output, as would a voltmeter. The problem is that at idle with a voltmeter, you're not really seeing the big picture. 14 volts is in the range. Assuming your battery is fully charged.

Let'* think about changing the O2. It'* got to be how old now? Basic rule of thumb is 50-60k miles or any time your fuel mileage drops, or fails to achieve what it should, or a rich condition.

Even if it doesn't fix the problem, it probably is due at this point. Time to order one, and in the meantime, we can make sure you've got enough spark voltage. How about a voltage check at idle, warmed up, after driving (to make sure the battery is fully charged and not demanding too much), as well as a coil pack resistance check. We can cover the most likely bases in the next few days that way.
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Old 03-30-2006, 11:15 PM   #6
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Short trips with a lot of low rpm city driving and warm up cycle will run rich and foul plugs.
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Old 03-30-2006, 11:34 PM   #7
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it might be my short trips, my job is only 7 miles away, and my plugs, wires, coils, and ignition module are all new, ill look into the alternator and o2 sensor, the sensor is due and the alternator has a squeally bearing anyway
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