Mechanics

CHEVY PO171 AND VERY RICH FUEL CONDITION

1998 Chevrolet Cavalier

Engine Performance problem
1998 Chevy Cavalier 4 cyl Front Wheel Drive Automatic 96259 miles

MY 98 CAVALIER IS FAILING EMISSIONS, STARTED OUT AS PO171 CODE, THEN OTHERS, LONG STORY SHORT, EVERY SINGLE SENSOR HAS BEEN REPLACED, SO HAS THE FUEL PUMP, PRESSURE REGULATOR AND PCM. IVE SPENT OVER $1800 AND THE CHEVY DEALER WAS ITS LAST STOP WHERE THEY SAID IT WAS THE PCM AFTER CHARGING ME $450 TO CHANGE THE MASS AIR FLOW SENSOR AND OXY SENSOR AGAIN! SO A NEW PCM IS INSTALLED TOO AND IM BACK TO THE ORIGINAL PO171 AND STILL FAILING EMISSIONS. THE DEALER CHECKED FOR VACUME LEAKS AS DID I AND NONE HAVE EVER BEEN FOUND. I KNOW THE PROBLEM IS STARING ME IN THE FACE BUT IM LOST, I HAVE A SCAN TOOL AND HAVE GONE THRU THE DIAGNOSTICS AS OUTLINED IN ALLDATA BUT STILL HAVE YET TO FIX THE PROBLEM. ON A LAST NOTE, WHEN EVER ANY COMPONET IS REPLACED, IT RUNS GREAT FOR ABOUT 10 MILES AND THEN BOOM BACK TO THE ORIGINAL PROBLEM. SINCE THE PCM HAS BEEN REPLACED, NOW I AM SEEING VISIABLE BLACK SOOT FROM THE EXAUST AGAIN (THIS PROBLEM STOPPED FOR A WHILE WITH NO REASONS) AND ITS ALSO RUNNING SUPER RICH AGAIN. HELP PLEASE!
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Lwico
August 5, 2008.




Did they perform a injector balance test to see how much the injectors are spraying. One may be spraying to much. Or a possiable EGR valve maybe sticking

Tiny
Rhall77
Aug 5, 2008.
Did they perform a injector balance test to see how much the injectors are spraying. One may be spraying to much. Or a possiable EGR valve maybe sticking

To add on it also have the fuel pressure check for a weak fuel pump /leaky fuel pressure regulator and PCV valve/hose

Scantool: A code P0171 indicates the engine is running lean. This means there is too much air and/or not enough fuel. You can confirm the engine is running lean by looking at Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT). Normally, STFT and LTFT should be plus or minus 8 from zero. If STFT and/or LTFT are more than about +10 or higher, it indicates the engine is running LEAN. Negative numbers (-10 or more) indicates the engine is running RICH
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Rasmataz
Aug 5, 2008.

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