Mechanics

PO171 AND PO174 FOR 4.3L HELP

1998 GMC Jimmy • 6 cylinder Automatic • 125,708 miles

I have did the following changes.

-Fuel filter=changed
-Fuel pressure regulator=changed
-Fuel pump=changed
-Mass air flow sensor=changed
-Air filter=changed
-o2 sensor on bank 2 sensor 1=changed
-Took off all six spark plugs inspected and cleaned them with carburetor cleaner
-inspected for lose hoses and wholes and leaks.
-Fuel injection service cleaning at Walmart

I took it too mechanic and they told me I needed now mass air flow sensor and fuel injection cleaning. After doing there recommendations I still get check engine light with PO171 and PO174. I hear a backfiring sound coming from engine compartment area intermittently on start once I step on gas then it takes off fast.
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Roycar71
September 4, 2012.




LOL, I will do first thing in morning thanks.


Tiny
Roycar71
Sep 30, 2012.
Your welcome the rum flavored ones are my favorites use a really bright flash light to look for the smoke.


Saturntech9
Sep 30, 2012.
I did smoke test with cigar. I did find that upper air duct that goes over throttle seemed to have comprised seal/gasket so I replaced it. Car drives good not one hesitation or stumbled, but still get po171 and po174 off and on; with rough idle when CEL comes on. My question, could it be a bad fuel injector. Thanks.


Tiny
Roycar71
Oct 13, 2012.
I have seen when you replace the mass air flow sensors on those with after market ones still having those lean codes. You could have a vacuum leak somewhere else also.
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Saturntech9
Oct 14, 2012.

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