2000 Chevy Silverado Warmup problems and P0137/P0157

YORNAMEHERE018

MEMBER
2000 CHEVROLET SILVERADO
V8
2WD
AUTOMATIC
136,000 MILES

I just bought a 2000 Silverado with a 4.8 and am having problems. It occasionally shows a check engine light for rear 02 sensor low voltage and it has almost no power when cold and low end is always weak. It takes about 10 seconds to get through 1st gear. It has no misfire and every once in a while it will pull really hard like it should.

I have:
Changed plugs
Used a can of Seafoam
Poured 2 cans of B12 into a full tank
Cleaned the EGR, IAC, and throttle body
Replaced a rear oxygen sensor (light still shows bank 1 and bank 2 rear sensors)
Checked fuel pressure (holds at 55 psi)
Changed fuel filter
Fixed a cracked line going to pressure regulator
Replaced the pressure regulator and intake gaskets

The intake gaskets seem to have helped but there is still somethng wrong. It has a tiny surge while idling, but not enough to show on the tachometer. Also, the check engine light only comes on at highway speed and full throttle. Here is a freeze frame:

Code P0137
100% throttle
3399 RPM
35.6% Engine Load
79.23 GR/Sec MAF
MAP sens 98 KPA
Coolant temp 199*
Short term fuel trim 1 0.8%
Long term trim 1 24.2%
Short term trim 2 0.8%
Long term trim 2 23.4%
Short term trim 3 -96.7%
Long term trim 3 -55.1%
Short term trim 4 -89.7%
Vehicle speed 80 mph
Fuel system 1 OPEN1
Fuel system 2 OPEN1

Thank you

2 Replies

MERLIN2021

MECHANIC
17,250 POSTS

Using scan tool, observe Long Term (LT) fuel trim values at different RPM and air flow conditions. Scan tool should display fuel trim cells so that LT fuel trim values can be check in each cell to determine when DTC may have set. If DTC is set, LT fuel trim values will be about 158 or greater. Check for mispositioned HO2S 2 wire pigtail contacting exhaust manifold. Check for intermittent ground in wire between connector and sensor. Check for poor VCM to engine block ground. Check for lean fuel injectors. Check for water near in-tank fuel pump inlet that may be delivered to injectors. Water causes a lean exhaust and can cause DTC to set. System will be lean if fuel pressure is too low. Monitor fuel pressure while driving vehicle at various speeds and loads to verify pressure. Check for an exhaust leak that can cause outside air to be pulled into exhaust and past sensor. Check for vacuum or crankcase leaks that can cause a lean condition and possibly high idle. If all above checks are okay, HO2S 2 is faulty. DO NOT solder HO2S 2 wires. Also 02 wires breath through the insulation and connector, so NO grease!

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Monday, August 3rd, 2009 AT 4:22 PM

GMC1999

MEMBER
1 POST

Did you solve this problem?
I have a 1999 GMC with the identical problem
eng light comes on, lack of power when cold, no low end when pulling out.
Used Seafoam after problem started.

P0137 O2 Circuit Low Voltage (Bank 1, Sensor 2)
P0157 O2 Circuit Low Voltage (Bank 2, Sensor 2)

Here is the last freeze frame
MIL ON
MisFire Monitor Complete
Fuel System Monitor Complete
Comprehensive Component Monitor Complete
Catalyst Monitor Complete
Heated Catalyst Monitor Not Supported
Evaporative System Monitor Complete
Secondary Air System Monitor Not Supported
A/C System Refrigerant Monitor Not Supported
Oxygen Sensor Monitor Complete
Oxygen Sensor Heater Monitor Complete
EGR System Monitor Complete

DTC for which Freeze Frame was Stored P0137
Fuel System 1 Status Open Loop - due to driving conditions
Fuel System 2 Status Open Loop - due to driving conditions
Calculated LOAD Value 46.27 %
Engine Coolant Temp 91 °C

Short Term Fuel Trim - Bank 1 -0.78 %
Long Term Fuel Trim - Bank 1 24.22 %
Short Term Fuel Trim - Bank 2 -0.78 %
Long Term Fuel Trim - Bank 2 24.22 %

Intake Manifold Absolute Pressure 94 kPa
Engine RPM 4108 rpm
Vehicle Speed Sensor 90 km/h
Air Flow Rate Mass Air Flow Sensor 99.21 g/s
Absolute Throttle Position 100.00 %

Just cleaned and checked the MAP, checked all clamps
Fuel filter next.

Thanks for any feed back.

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Saturday, August 11th, 2012 AT 1:44 AM