What sensor commands IAC, TPS only?
04-15-2006, 11:41 AM
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What sensor commands IAC, TPS only? I have a P0507 that not even God can fix. Car idles fine in park or neutral however when in gear and driving down the road car idles at 1500 until coming to a complete stop and sitting for 10-15 seconds. Per the GM service manual for P0507, only failures are IAC valve, faulty PCV valve, PCM or vac leak.
Here is what I have done, swapped with known good PCM, same problem, replaced IAC valve, same problem, replaced PCV same problem. I changed TPS for good measure same problem. Only other viable cause would be vac leak however all hose checked and entire engine sprayed extensively with starting fluid and no leak found. Also if I disconnect IAC, I can drive for hours with no high idle, which to me eliminates theory of vac leak, because it was a vac leak idle would raise regardless of IAC or not?
Car idles all day long in park or neutral and does not change, but once in gear it raises to 1500 and car drives it self until coming to a stop for an extended period of time 10-15-20 seconds.
I have done no changes to the car prior to this problem, and based on all my troubleshooting per GM service manual no cure has been found.
Knowing that it only does it when IAC is plugged in leads me to believe for some reason some sensor is commanding the IAC to raise idle. Other than TPS, does any other sensor command the IAC that could be at fault? MAP?
Here is what I have done, swapped with known good PCM, same problem, replaced IAC valve, same problem, replaced PCV same problem. I changed TPS for good measure same problem. Only other viable cause would be vac leak however all hose checked and entire engine sprayed extensively with starting fluid and no leak found. Also if I disconnect IAC, I can drive for hours with no high idle, which to me eliminates theory of vac leak, because it was a vac leak idle would raise regardless of IAC or not?
Car idles all day long in park or neutral and does not change, but once in gear it raises to 1500 and car drives it self until coming to a stop for an extended period of time 10-15-20 seconds.
I have done no changes to the car prior to this problem, and based on all my troubleshooting per GM service manual no cure has been found.
Knowing that it only does it when IAC is plugged in leads me to believe for some reason some sensor is commanding the IAC to raise idle. Other than TPS, does any other sensor command the IAC that could be at fault? MAP?
07-17-2006, 07:58 PM
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Here ya go dude... http://autorepair.about.com/cs/troub...042603a_08.htm
I'm having a very similar problem. I checked the IAC Motor Position with ATap, and it always shows 0. Calculated engine load, battery voltage, engine cooling temp and engine RPM all come into play here. That link will also help you with a troubleshooting suggestion. I'm going to take mine into work and put a power supply across the terminals and see if the pintle moves. This doesn't rule out an open circuit, but it's a place to start. Good luck.
Day late and a dollar short?
I'm having a very similar problem. I checked the IAC Motor Position with ATap, and it always shows 0. Calculated engine load, battery voltage, engine cooling temp and engine RPM all come into play here. That link will also help you with a troubleshooting suggestion. I'm going to take mine into work and put a power supply across the terminals and see if the pintle moves. This doesn't rule out an open circuit, but it's a place to start. Good luck.
Day late and a dollar short?
