• Tiny
  • sickoftheMIL
  • 2008 Chevrolet Silverado

Engine Performance problem
2008 Chevy Silverado V8 Four Wheel Drive Automatic 62000 miles

I'll try to keep this short.
A few weeks ago while traveling, my engine dropped a valve under warranty. A bunch of white smoke later (I assume a compromised combustion chamber) it was flatbedded to the nearest dealership. The dealership replaced the engine under the Powertrain Warranty - so far, so good. Since I live about 3 1/2 hours away from where the truck died, when it was complete I had to pick it up on a Friday night after hours. I got in it, drove 30 miles or so, and the check engine light came on - P0171 and P0174.
On Monday, I called the dealership (remember, 3 1/2 hours away) who informed me the problem was emissions related and NOT under warranty. I won't bore you with the details of arguing with "customer service" reps that one thing probably led to the other. But I'll get to where I am now.

I had the engine scanned at a local dealer, where I was told both the upstream O2 sensors were bad. To save a few dollars, I replaced them myself. Same Problem. I signed up for the Mitchell manual, and started through the diagnostics. Thus far, I've replaced not only the O2 sensors, but the MAF and MAP sensors as well. I still get the same codes. I was able to borrow an inexpensive scanner, and here's what the freeze frame is showing:
B1 - Closed Loop, using HO2S
B2 - Closed Loop, using HO2S
Calculated Load 11.76%
Coolant Temp 89 degrees C
ST Fuel Trim B1 6.23%
LT Fuel Trim B1 29.67%
ST Fuel Trim B2 10.14%
LT Fuel Trim B2 29.67%
MAP 41 KPa
Engine Speed 1077.50 RPM
Vehicle Speed 59 Km/hr
Ignition Timing29.50 BDTC
MAF 4.82 g/s
TPS 21.56%

I'm pretty much at a loss where to look next. Any help would be appreciated! I was supposed to leave on vacation today, so I have a pretty displeased wife!

Do you
have the same problem?
Monday, June 28th, 2010 AT 11:48 PM

1 Reply

  • Tiny
  • rasmataz
  • Member

Lean fuel condition could be caused by one of the following below:

1. Vacuum leaks

2. EGR and PCV valve.

3. Low fuel pressure.

4. Dirty fuel injectors.

5. Mass Air Flow Sensor.

6. Oxygen Sensor.

Was this
Tuesday, June 29th, 2010 AT 12:06 AM

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