Help me trouble shoot... MORE confusion

I finally took to a "real" mechanic, but they were stumped. I do all of my own work usually. I maintain my cars like gold.

2010 Chevy Aveo 5 LT 124, 896 Miles

RECAP: Back on June 3rd car was stalling out at stop, and also happened to be running lean. After the stalling occurred, difficulty with acceleration was noted, jerking, and sometimes it felt like I would push the pedal and nothing would happen.
CEL codes ALL O2 sensor related.

During my saga I have replaced :
Camshaft/Crank shaft pos sensors
Throttle Body (Which also houses Air intake Control Valve within it)
New Intake hoses
MAF sensor
Spark plugs (Gapped Correctly)/Spark plug coil pack for good measure
VALVE cover gasket AND valve cover( PCV) valve integrated.
Super duper Fuel injector service
Upstream and Downstream O2 sensor with OEM sensors.

NO MORE STALLING, YAY!!

STILL RUNNING LEAN and no one can tell me why.

I had a smoke test performed, smoke came out a teeny tiny bit around the MAF plug in, so I sealed it up. No other apparent leak.

Current CEL codes.
P0137
P2270
P0053

Now remember, I have OEM brand new O2 sensors from just 2 months ago.

Why am I still running lean?

Fuel pressure is solid as a rock. O2 sensors are good voltage per computer.

Could this be an EVAP issue even though smoke test didn't show any leak?

My fuel filter is integrated into pump, should I replace the whole thing?

I would appreciate the insight.

With lean conditions, I’m leaning towards a vacuum leak.
oxygen sensors can be finicky about their grounds, so there is another Avenue to look at…

Just wondering if anyone has touched the fuel injectors recently? I replaced the fuel injectors on my 2009. About 2 years later, the CEL came on for a lean condition. When the engine was idling, i could hear a slight hissing sound. After much searching and troubleshooting, it turns out one of the fuel injector seals was damaged when i changed them 2 years previously. It was my own fault for damaging the fuel injector seals. This might be an unusual and rare example of a vacuum leak. But it's a good example that vacuum leaks can be found in unexpected places.

Deano

Quote:

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Originally Posted by AveoChick

I finally took to a "real" mechanic, but they were stumped. I do all of my own work usually. I maintain my cars like gold.

2010 Chevy Aveo 5 LT 124, 896 Miles

RECAP: Back on June 3rd car was stalling out at stop, and also happened to be running lean. After the stalling occurred, difficulty with acceleration was noted, jerking, and sometimes it felt like I would push the pedal and nothing would happen.
CEL codes ALL O2 sensor related.

During my saga I have replaced :
Camshaft/Crank shaft pos sensors
Throttle Body (Which also houses Air intake Control Valve within it)
New Intake hoses
MAF sensor
Spark plugs (Gapped Correctly)/Spark plug coil pack for good measure
VALVE cover gasket AND valve cover( PCV) valve integrated.
Super duper Fuel injector service
Upstream and Downstream O2 sensor with OEM sensors.

NO MORE STALLING, YAY!!

STILL RUNNING LEAN and no one can tell me why.

I had a smoke test performed, smoke came out a teeny tiny bit around the MAF plug in, so I sealed it up. No other apparent leak.

Current CEL codes.
P0137
P2270
P0053

Now remember, I have OEM brand new O2 sensors from just 2 months ago.

Why am I still running lean?

Fuel pressure is solid as a rock. O2 sensors are good voltage per computer.

Could this be an EVAP issue even though smoke test didn't show any leak?

My fuel filter is integrated into pump, should I replace the whole thing?

I would appreciate the insight.

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when you replaced the throttle body, did you do the idle relearn? because if you didn't, the IAC will close too far and will basically choke the intake and cause it to stall.

Yes! I was able to perform the idle relearn.

I did perform a fuel injector super clean back 4 weeks ago.
I don't hear any hisses.

It DOES lose a hell of a lot of power when the AC is on, which might be a good hint.

The smoke test did not show any vacuum leak.
Hmmmm..grounds, that is another angle to go with.

Deano-

For kicks and grins I am going to go ahead and replace the injectors.

Sorry, I didn't mean to give the impression that i thought the fuel injectors were the problem. I only meant to say that vacuum leaks can possibly happen at the fuel injectors, especially if they've been touched recently. If you do go ahead and replace them, remember to lubricate the injector rubber seals with a slight coating of motor oil, or else the rubber seals will get torn.

Deano