Help with sensor problems

in may i went to a chevy dealer where my buddy worked and had him look and see why my truck doesnt run all that well. he plugged intheir diagnostic tool thing and it said that my motor was running really lean, so it said to replace the O2 sensor (i think it was running at 400 and was supposed to be running at around 700...im not sure on the units). So i replaced that sensor and nothing changed. Does this mean I have a problem with my ECU? my truck idles very rough (like its about to die) in cold weather and it improves a little bit in warmer weather, but it still runs terrible. any help would be greatly appreciated. Thanks, Dylan

I Make a same mistake a while ago, until some techdude told me that the sensors R there to tell a situation, If the sensors R telling ur too lean, I'll check else where..injectors, pump pressure, Calibration!!!!

A MAF got south or something like that, I just check to see that for manteinance you can change ur O@ sensors every 100.000 miles, but with ur Gas probably they last more.

<div class='quotetop'>QUOTE(Gabe &#064; Sep 7 2006, 05&#58;48 PM) [snapback]64299[/snapback]</div>

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I Make a same mistake a while ago, until some techdude told me that the sensors R there to tell a situation, If the sensors R telling ur too lean, I&#39;ll check else where..injectors, pump pressure, Calibration&#33;&#33;&#33;&#33;

A MAF got south or something like that, I just check to see that for manteinance you can change ur O@ sensors every 100.000 miles, but with ur Gas probably they last more.
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well my truck is TBI so i only have like 2 injectors..i might go buy me a TBI rebuild kit and see what happens..and calibration ? what do you mean?

Thanks

TBI dude,

Now lest talk, I handle here like 6 TBI trucks with some basic problems.

I&#39;ll tell you what so far worked for me on some problems&#33;&#33;&#33;

When the trucks here idle bad I always goes first for the IAC, on this models in tends to build a lot of carbon, and sometimes cleaning ir helps a lot.

The trucks here R 94-95 most, so on some I have changed from brand new.

If u have no chip change and running stock, and running lean, then I&#39;ll be cheking the presure on the inyector rail, If yu can test with another MAP sensor just to kill that option. And the other thing, R u still working The EGR system? I cancelled all of those and the trucks improve some&#33;&#33;&#33;

Other thing will be the injectors, down here I have to change fuel filters 3000km and clean injectors every 8 month due to the same dirty gas problem&#33;&#33;&#33;

It hepls a lot to have a few trucks of the same year so I can interchange some parts and find faster and cheaper the problem

Check your fuel pressure to be sure that it is within specs. Too low, lean, too high, rich.

Get a gauge pod with air/fuel gauge then mount you a fuel pressure gauge. I have one and I new immediatly when my rear o2 sensors where going bad. Just a suggestion for future problems.

<div class='quotetop'>QUOTE(Gabe &#064; Sep 8 2006, 01&#58;27 PM) [snapback]64368[/snapback]</div>

Quote:

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TBI dude,

Now lest talk, I handle here like 6 TBI trucks with some basic problems.

I&#39;ll tell you what so far worked for me on some problems&#33;&#33;&#33;

When the trucks here idle bad I always goes first for the IAC, on this models in tends to build a lot of carbon, and sometimes cleaning ir helps a lot.

The trucks here R 94-95 most, so on some I have changed from brand new.

If u have no chip change and running stock, and running lean, then I&#39;ll be cheking the presure on the inyector rail, If yu can test with another MAP sensor just to kill that option. And the other thing, R u still working The EGR system? I cancelled all of those and the trucks improve some&#33;&#33;&#33;

Other thing will be the injectors, down here I have to change fuel filters 3000km and clean injectors every 8 month due to the same dirty gas problem&#33;&#33;&#33;

It hepls a lot to have a few trucks of the same year so I can interchange some parts and find faster and cheaper the problem
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thanks for all the help..when you said if im still running the EGR< if that is the smog pump, then no. how can i get that part of the program removed from my PCM? what is the MAP sensor and what is the IAC? thanks