Mechanics

SERVICE ENGINE SOON LIGHT

Chevrolet Tahoe

I purchased a 1997 Chevrolet Tahoe, 4WDr, 171,000 miles, 5.7L engine and the service engine light soon continues to be lit. I changed both oxygen sensors, got it tuned up, and have added fuel injector cleaning fluid to a tak of gas. I got it scanned this afternoon with the scan indicating " rich fuel mixture" for both banks. After the computer was re-set I drove it 180 miles on the interstate without the engine light becoming lit. I then turned it off, waited about 30 minutes, and then went to the post office and it lit again after about 1/4 mile.
Any advise?
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Ltc123101
May 5, 2007.




I'm assuming there weren't any other codes when you had it scanned. You need to get it scanned with live data when driving it. The sensors which effect the airfuel mixture are the mass air flow sensor, manifold absolute pressure sensor, engine rpm sensor, engine coolant sensor, throttle position sensor, intake air sensor and the O2 sensors which you replaced. You need to get readouts while driving for these sensors and see if they're in range.
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Tiny
Rudpro
May 18, 2007.
Usually the ses light only relates to emmisions and fuel and a majority of my friends have tahoe's and silverados with the same engine. Therse are all the ses light problems we have had and how we fixed them.

1. If you installed a k& n air filter you need to clean your maf sensor with some carb cleaner because the oil from the filter cakes on the sensors.

2. If you changed your spark plugs with pre-set gaps you need to change them and set the gaps manually

3. If you changed your 02 sensors and still have the problem it really is your catalytic converters (this one happened to me)

*in my situation when my ses light came on, it was because I was running rich from my preset gapped spark plugs, once I changed out my spark plugs (3 months later) the light went away but it came back because I was running rich sooo long that it damaged my catalytic converters. I bit the bullet had them replaced and now its good to go.

Tiny
Simple_ryan
May 27, 2007.

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