Question about Chevrolet Avalanche
I have a 2005 chevy avalanche 5.3l The plugs are good, the wires are good. Has new Map sensor, Maf sensor, Air filter, Fuel pump, and throttle body. My fuel trims are like this. STFT B1 -0.8 to -3.9 LTFT B1 11.7 STFT B2 -3.9 to 1.6 LTFT B2 4.7 to 5.5 all of these numbers have a short term spike that jumps way down to -93.8 bouncing around. My O2 sensors read B1S1 STFT 34.4 B1S2 STFT 99.2 These readings were taken at idle only. Still unfamiliar with using my scan tool but...I'm slowly catching on. A little. I realize this kind of points to a vacuum leak but. I don't believe it is. The truck runs fine. It is only under hard acceleration do I experience problems. Other than that it drives and idles good. I did hear something about idle air control giving this sort of symptom but..I can't find that on this vehicle. I forgot to mention that there are no codes present also that I have changed the purge valve as well. Just so it is known. All those things I replaced had issues. I had to take care of them first.
Posted on Jan 23, 2019
Testimonial: "Thanks Carl. I did know of scanner danner and I did know that a vacuum leak on the intake would give those kind of readings but...Mine aren't that high and I have no codes and have tried setting a code by repeatedly doing what it does when it does it but it just won't set a code. I'll try the water thing as well as use the scan tool. As for the guy who said you just don't replace things and hope for the best. Everything I replaced had issues except for the map sensor but its gasket was very worn."
Cud b mass air flow sensor. A data stream run w factory scannr the most accurate..partstore readers just toys. Dont go to a dealr. Library has chilton shop manuals
Posted on Jan 28, 2019
If it had all those issues I expect high mileage. Check the cat. Converter.
Posted on Jan 24, 2019
Testimonial: "If there was something going on with the catalyst do you think it would give fuel trim readings like it does? On one bank?"
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Posted on Jan 02, 2017
You never replace anything, on a Wishing,Hoping,Pushing,Poking,diagnostic approach
You learn the vehicles Systems,Test,then Replace,if you have a failed component.
Work on the Misfire Issues.
Then you lean O2 Codes will go away.
Not a the plugs.
Think lean---Vacuum leaks,EGR Valve leak,EVAP System leaks,anything with a hose that lets air into the intake system.
Exhaust System leaks,near sensors
Posted on Nov 24, 2010
Check your fuel pressure, and or injectors. You may have too much fuel getting into the engine causing it to burn rich and overheat the converters.
Posted on Apr 26, 2009
These are very common codes on BMW's which can also be false codes, try clearing the codes and run the test again they may not come up again.
With regards to the sound which you thought was a vacum leak there a breather pipe which runs under the plastic engine cover near the injectors which always gets a tear init which will need replacing.
Hope this helps, please don't forget to rate me.
Posted on May 20, 2009
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