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Old 08-09-2015, 12:14 PM   #11
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I took a scan reading and both the ECT and the IAT was at 22 C. I started the engine and the coolant temp steadily climbed but the IAT stayed relatively the same, only climbing a few degrees.

Someone told me that failed sensors would set codes, that may be true of a failed sensor but a sensor that is sending incorrect data won't always set a code.
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Old 08-09-2015, 12:14 PM   #12
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If he was just looking at the data you showed us , that is just one instance in time....it'* quite possible both O2 readings were the same at once, and in another millisecond were quite different.......

You can't make any assessment on a cat, just by looking at one instant in time, like that....
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Old 08-09-2015, 12:22 PM   #13
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If he was just looking at the data you showed us , that is just one instance in time....it'* quite possible both O2 readings were the same at once, and in another millisecond were quite different.......

You can't make any assessment on a cat, just by looking at one instant in time, like that....
When my friend was here; that worked on cars for a living at one time, he did not say anything about a bad cat. He was thinking that maybe my intake had developed a leak (it has been six months since I replaced the intake gaskets; would they leak after six months?). I don't want to go pulling intakes, that is a major job, unless I know for sure. I can try the car cleaner test around the intake and see; I have not tried that.
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Old 08-09-2015, 12:46 PM   #14
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I took a vacuum reading from the port on the upper intake plenum. It read 20 inch Hg at an engine rpm of around 1300 to 1400 by the dash gauge.
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Old 08-09-2015, 02:16 PM   #15
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I found the problem. As I said, this car was given to me with limited repair history. By the way, I did the carb cleaner test for vacuum leaks and nothing happened to the rpms. I decided to do the sensor wires wiggle test and that turn up nothing. I remember that 0.4% throttle position sensor and decided to wiggle the throttle cable and dang if the rpm did not change. I got to inspecting the cable and the clip that holds it in place on the bracket had evidently broken and someone used a wire tie to hold it in place. When I installed the new ICV (for the inconsistent idle and PO507 code) I must have put my hand on that bracket to steady myself and pushed the cable out of place. Evidently the butterfly was slightly open and maybe even moving as the engine ran. I am going to drive the car and let the PCM calibrate and see how it goes and to see if the PO507 code returns (I cleared all codes as I set some trying to test things by unplugging things). I will update this post.
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Old 08-09-2015, 02:23 PM   #16
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Dang five minute rule.

P.*. I am still going to change the coolant temp sensor since I have it coming; call it preventive maintenance.
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Old 08-09-2015, 09:41 PM   #17
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Update:

Drove the car about 40 miles or so. No trouble codes set, no trouble codes pending. However, a few times the car hesitated when accelerating from a traffic light. I press the accelerator to start moving from the stop position and it hesitated before moving; scary feeling in heavy traffic because some idiot could rear-end me if it stalled completely.

Plus, the idle still isn't quite right but I am thinking the throttle body really needs to come off, all sensors off, and a proper cleaning done based on what I saw when I did the intake leak. I did clean what I could at the time.

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Idle Problem first, now high idle 98 Buick LeSabre-throttle-body.jpg  

Last edited by Kimberly; 08-09-2015 at 09:43 PM.
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