chevy check engine more info

went to the shop and got a couple codes PO171 system too lean bank 1 and PO300 random misfire detected this is on 04 silverado 5.3L 45,000 miles cleared the codes new fuel and isopropal went for a drive light started blinking again. Kicked it down and black smoke came out like a diesel. lights went off and engine idle back to normal awhile later the light came back on and stayed on solid engine idle still fine will the light remain on until the codes are cleared with scanner or if everything is fine will the light turn off by itself? thanks for all the help so far.

My guess is intake gasket, especially if its going lean. You can try spraying carb cleaner around the intake plenum with it running, if the engine speeds up you have a leak someplace. I know the older vortechs had that problem, I’m not to familiar with the 5.3 though.

Good luck

The P0300, is misfiring, has the truck had a tune-up recently ? Plugs should be due at 30 or 60K I would think. The Bank 1 lean, I would “lean” (no pun intended ) toward an Oxygen sensor.

big G

I just went through this for a gentleman down here ..Same codes but he also had a P0172 bank 2 code.

We ended up doing an intake manifold gasket and a FULL tune up .. filters ,plugs and wires.

MAKE SURE if you do a intake manifold gasket you purchase one from a dealer.. There has been several updates to that gasket due to a poor design and that I am awhere of only dealers had the newest version.

I have done 6 or so jobs of that era truck and all run great now.

Hope this helps you some

My guess is an o2 sensor is reading lean all the time, in return it is dumping as much fuel as it can on bank one. This creating miss fire..I bet the cylinders miss-firing were 1 3 5 7.We have seen 5 o2 sensors do this in the last week…

i have had where the catalatyc converter was getting plugged to find out for sure should have a scanner hooked up and see whats going on with the motor have fun and good luck steve

O2 sensor are pretty cheap if you do them yourself aren’t they?

If it were an O2 or an injector, wouldn’t these throw specific codes for those two items? A whole bank misfire makes me think maybe the upper intake leaking or a vacuum problem somewhere as mentioned? How’s the exhaust at idle, white smoke at all, smell coolant? Or the coolant, smell oil? All fluids up to level?

Oh, to answer you question. Typically I think the code will clear after so many key cycles if the error is no longer present, not sure how many cycles (10-20?) tho. Swing by an auto parts store and have it cleared for no charge, they may make you push the clear button as sometimes they don’t want the liability!

well to the shop again different one much better diagnostics showed how many misfires (12,856) at 53.3mph on bank one replaced O2 sensor and good too go sensor 170.00 good too know about auto stores checking codes for future use any specific one’s?

Hey, great news. AutoZone does mine no charge, heck I’m in there weekly! The Yuk has 230,000 miles, still going forward!

My check engine light came on and I had my mechanic check it and he said it was the catalitic converter. If I sold the car I would have to have it fixed first. He reset it and we went to Florida on vacation and it came back on. I drove for a week and then bought a can of sea foam and poured half a can in a full tank and drove for 2 days and the light went off. Came back on a week later and put the other half can in and it went off and has never came back on again. Yea sea foam

Good to hear you got it sorted out and fixed for a reasonable price – if there is such a thing anymore!

As carboned up as it sounded like it was, it would probably be a good idea to give it a couple more “blast the carbon out” runs to clean the crud out.

Dan