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#1
06-30-2007, 06:44 AM
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O2 issues
I have posted a couple times about a couple of problems all leading back to the O2 sensors. The codes I am pulling up are O2 sensor low voltage bank 1 sensor 1 and bank 2 sensor 1. I know these are the two sensors before the cat and I replaced them with bosch (it was the only brand I could find locally) wich seemed to make the problem worse. I have used a test light to check for power at the sensors and got good readings. Does low voltage mean the power going to the sensor or voltage coming back from the sensor. I have also noticed in diagrams that the sensors are on the same fuse as the cam position sensor and the mass airflow sensor. I am in a bind here because this issue with my truck is not letting me leave the area due to the fact that I can not climb any hills without the truck jerking and wanting to die out. Any help would be much appreciated, I am loosing sleep over this as you can see by the time of my post. The truck is a 96 chevy suburban K1500 5.7 with 173000 on it.
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#2
06-30-2007, 09:49 AM
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Re: O2 issues
Assume that the O2 sensors are reading an actual lean condition (low voltage). Here are some conditions that can cause this. Also I'm assuming the codes were P0131 & P0151??
1. Exhaust leak between the engine and sensor. 2. Vacuum leaks. 3. Incorrect fuel pressure. 4. Lean fuel injectors. 5. Inaccurate MAF sensor
__________________
57 Chevy 210 65 Olds 442 Convertible (Another one sold) 75 GMC Vandura 3/4 Ton 1999 K2500 Old Body Style Suburban (Gone but not forgotten) 05 Dodge Ram 3500/5.9 Cummins 2012 Toyota FJ Cruiser
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#3
06-30-2007, 10:29 AM
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Re: O2 issues
Fuel pressure and fuel mix affects the 02 sensors.
Also MAF sensor and Tempture sensors. What is the fuel trim reading? Engine and code no?
__________________
Remember proper testing gives us the answer to many problems. MT
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#5
06-30-2007, 05:48 PM
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Re: O2 issues
You will need a good engine capable scanner.
All of the pcm and sensor reading and code no will be in it.
__________________
Remember proper testing gives us the answer to many problems. MT
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#6
07-02-2007, 10:32 PM
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Re: O2 issues
If I just check the fuel pressure before the injectors would that tell me anything? Also would bad plugs cause a lean or low voltage reading on the 02 sensors. I just replaced them but maybe they are faulty. If I had a bad injector would I get a code or would it idle rough? The truck idles fine but accelerates like crap.
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#7
07-02-2007, 11:43 PM
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Re: O2 issues
Quote:
__________________
Remember proper testing gives us the answer to many problems. MT
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#9
07-03-2007, 10:02 AM
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Re: O2 issues
If it is on the fuel rail or line yes.
Fuel specs 60/66 Check cold start fuel pressure. Check engine running fuel pressure. Check engine running on the road fuel pressure. Then shut it off and watch for fast leak down. Pinch off at rubber part or block off return line and check full pressure. Later V6 and V8 gm engines should have 60-66 fuel pressure. Cold start should be 64-65 lbs of pressure. If you do not have full fuel pressure on a cold start the injectors will not squirt fuel. Do not leave home without it. Engine running should be 60-66 lbs pressure depending on engine load. Full pressure with return pinched off should be 75-85 or more. And if it has a fast leak down after shut off you have a leak. Post back fuel pressure readings.
__________________
Remember proper testing gives us the answer to many problems. MT
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