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Discussion Starter #21
Hi All,

Another update. I started the car and it idled fine, around 1,100 rpms then down to 880 rpms for several minutes. I could give it a squirt of throttle and it would settle back around 1,000-880 rpms. I turned the car off, back on, same deal. I thought great - so I did the on, off, on, etc. procedure to have the tps 're-calibrated.' But once the car got up to temp, the idle started increasing. From 1,200 to 1,500 to 2,000 back to 2,250 fully warmed up. Went for a drive, same deal, idling at 2,250 rpm.

Before setting off I pulled the CEL codes with my OBDLink bluetooth unit then cleared the registry. Here's what it had recorded:

P0122 - Throttle/Pedal Position Sensor/Switch "A" Circuit Low
P0223 - Throttle/Pedal Position Sensor/Switch "B" Circuit High
P0507 - Idle Air Control System RPM Higher than Expected

I looked through the report and saw idle pedal position was around 12.5%

So the last code seems to be straightforward - the computer is seeing the idle is high and throwing a warning. The first two P0122 and P0223; I'm wondering if that is due to a bad sensor/switch or if there is a short in the harness somewhere. I'm terrible with electronics but pops is an ace - so I'm going to have him go through with a multimeter and see if there is something amiss coming off the loom to the TPS. I take it I should be looking for 0.5V at idle and 4.5V+ at WOT on the sensor itself.

What would another solution be for this? A new throttle body unit (ACDelco) is $136 on Amazon. Can the TPS itlsef be separated and replaced from our units or are they internally integrated? It looks like I'd need to swap the whole actuator.

Trying to think about this... the car in open loop upon start-up idles fine. Once in closed loop mode the high idle problem starts. Could it be an emissions protocol running off a faulty 02 sensor? But wouldn't I get some sort of check or code if that were the case? Could it be the MAP Sensor? The MAF Sensor? I feel like these would have their own trouble codes if they were faulty but I don't want to rule anything out... Any/all feedback is appreciated. Thanks all thus far!
 

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I would find and fix the throttle pedal position sensor problem first. The throttle could be reacting properly to an incorrect input.

Given that it is both high and low I suspect the sensor, but it will take a look at the description in the manual to be sure.
 

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The easiest and fastest way to find the source of a fluid leak is UV dye.

I rolled my eyes at this for years until I saw a Real Mechanic use it to find a leak on my G35 in about 20 minutes. Put some dye in wherever you normally add the fluid in question, run the engine for a bit, put on the fancy yellow filter goggles and shine the included UV flashlight around until you can see the source. The kit cost me about $50 off of Amazon a few years ago. I've used it to find coolant, oil, AC and steering leaks when just looking around with a flashlight didn't work.
 
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