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Old 11-20-2003, 09:07 AM   #22
RABarrett
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Join Date: Sep 2003
Location: Carson City, Nevada
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Something to consider here. The computer sets codes for several reasons, but the bottom line is simple. The ECM compares sensor readings to what is programmed into it, comparing sensor readings, and comparing them to established parameters in the software. If the EGR valve code is set, it is because the EGR sensor "readings" "appear" to be off. The software could have been corrupted, the sensor itself could be intermittent, other comparative sensors, such as the TPS, airflow meter, or any other engine sensor used to calculate load could be the culprit. Simply "knee-jerking" to what the computer says is indicative of a thorough misunderstanding of how the system operates. My dog could fix cars if it was that simple. It is also possible for plug wires to cause an EGR code if the engine's surging is caused by this. Think about it; the engine surges due to the plug wire condition, the computer thinks the EGR valve is not open wide enough to cause that, it therefore "thinks" the EGR valve is then the cause. The computer cannot test plug wires, it can only guess at what is causing the miss; if it sees surge, it compares this condition to the EGR valve position, assumes the EGR is at fault due to "multiple" misfires, and reacts. The tech also reacts since he is as uninformed or as stupid as the computer is and replaces the indicated part at your expense. Voila, a misdiagnosis, an unhappy customer. The vehicle's systems are not the problem, techs are. My advise: the next time your vehicle is in the shop for something like this, insist that the tech prove to you that he has correctly diagnosed the problem and is replacing the correct part. Any time I dealt with customers, I explained to them the problem, how it affected the vehicle's performance, and showed them the defect. It is ok to play stupid here. If you do not understand what is happening, insist that the tech show you. It is his responsibility, nee his obligation, to explain, to your satisfaction, what has happened. Informed customers were my best customers. The more questions they asked, the better I could explain the problem, making the "sale" easier. Tell the tech that you want to see what the computer is telling him. The computer will display a freeze frame display of the events surrounding the event that set the code. If he thoroughly understands the event, he can explain it to you. If he cannot explain it to you, he cannot properly fix the problem. I will assist in any way I can. My apologies for climbing on my soap box. Ray
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