P0505 Gremlin - Already fixed IACV and ECU
07-21-2016, 04:06 PM
#1
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Join Date: Feb 2009
Posts: 6
P0505 Gremlin - Already fixed IACV and ECU
I'm still chasing a P0505 in a 2001 Maxima. It started when the IACV solenoid burnt out which blew out the STA509A MOSFET in the ECU. I got that replaced and fixed and confirmed they are working fine by:
1. Replaced STA509A and confirmed all traces are good on the circuit board
2. Using a genuine Nissan IACV. Confirms 22 Ohms between pins 1-2, 2-3, 4-5 and 5-6. Visually confirmed solenoid expands and contracts outside of IACV
3. Unplugged both engine mounts as I don't know what state they are in and I don't wish to replace them
I did the IACV relearn via removing the TPS (brown plug) method. That brought the idle down to about 580 RPM. Much too low for the 700 RPM +/- 50 RPM spec and automatic should have. At this idle speed, stop and restart of the engine within 10-15 seconds results in a stall as the RPM is too low. If i wait longer, it holds at about 580-600 RPM. If I turn on the A/C it drops to about 500 and the car vibrates. A/C fails to cool the car (sounds like it's disengaging the compressor because there isn't enough RPM). P0505 pops up after about 10-15 miles of driving.
If I adjust the throttle body screw (yes, I know it shouldn't be adjusted but found this out after the fact) to get it 700 RPM with no accessories or A/C on, it holds well, drives well, and no stalls after immediate restart. A/C works flawlessly. But after about 100 miles P0505 pops back up. On a cold start it does idle high for awhile but after 20-30 mins it does go back to 700 RPM.
I found the procedure to calibrate the TPS. So with the throttle body out of the car, I used a thin feeler gauge as described to position the throttle screw to its max position but still register continuity on the throttle closed sensor. I tighten the screw at this point. A thicker feeler gauge showed open circuit on the throttle closed sensor. I put it back in and the car is back at idling at 580-600 RPM. IACV relearn does not help. Also note with the throttle screw set to 700 RPM, the throttle closed sensor does not show continuity.
I'm thinking adjusting the screw back to 700 RPM and then taking the throttle body out and re positioning the TPS so that it show continuity on the throttle closed sensor. This is described in the TPS calibration sheet in the service manual. Would this possibly work? Would idling at the correct RPM (700 +/- 50 RPM) but the throttle closed sensor open throw a P0505 or something other code?
What exactly throws a P0505? Is it because the RPM is below 650 or greater than 750 at idle for a certain amount of time? Is there anything else that can throw P0505?
Note that I'm using an ODB-2 scanner to get RPM readings, not the tachometer so these numbers are accurate.
1. Replaced STA509A and confirmed all traces are good on the circuit board
2. Using a genuine Nissan IACV. Confirms 22 Ohms between pins 1-2, 2-3, 4-5 and 5-6. Visually confirmed solenoid expands and contracts outside of IACV
3. Unplugged both engine mounts as I don't know what state they are in and I don't wish to replace them
I did the IACV relearn via removing the TPS (brown plug) method. That brought the idle down to about 580 RPM. Much too low for the 700 RPM +/- 50 RPM spec and automatic should have. At this idle speed, stop and restart of the engine within 10-15 seconds results in a stall as the RPM is too low. If i wait longer, it holds at about 580-600 RPM. If I turn on the A/C it drops to about 500 and the car vibrates. A/C fails to cool the car (sounds like it's disengaging the compressor because there isn't enough RPM). P0505 pops up after about 10-15 miles of driving.
If I adjust the throttle body screw (yes, I know it shouldn't be adjusted but found this out after the fact) to get it 700 RPM with no accessories or A/C on, it holds well, drives well, and no stalls after immediate restart. A/C works flawlessly. But after about 100 miles P0505 pops back up. On a cold start it does idle high for awhile but after 20-30 mins it does go back to 700 RPM.
I found the procedure to calibrate the TPS. So with the throttle body out of the car, I used a thin feeler gauge as described to position the throttle screw to its max position but still register continuity on the throttle closed sensor. I tighten the screw at this point. A thicker feeler gauge showed open circuit on the throttle closed sensor. I put it back in and the car is back at idling at 580-600 RPM. IACV relearn does not help. Also note with the throttle screw set to 700 RPM, the throttle closed sensor does not show continuity.
I'm thinking adjusting the screw back to 700 RPM and then taking the throttle body out and re positioning the TPS so that it show continuity on the throttle closed sensor. This is described in the TPS calibration sheet in the service manual. Would this possibly work? Would idling at the correct RPM (700 +/- 50 RPM) but the throttle closed sensor open throw a P0505 or something other code?
What exactly throws a P0505? Is it because the RPM is below 650 or greater than 750 at idle for a certain amount of time? Is there anything else that can throw P0505?
Note that I'm using an ODB-2 scanner to get RPM readings, not the tachometer so these numbers are accurate.
07-21-2016, 04:10 PM
#2
I'm still chasing a P0505 in a 2001 Maxima. It started when the IACV solenoid burnt out which blew out the STA509A MOSFET in the ECU. I got that replaced and fixed and confirmed they are working fine by:
1. Replaced STA509A and confirmed all traces are good on the circuit board
2. Using a genuine Nissan IACV. Confirms 22 Ohms between pins 1-2, 2-3, 4-5 and 5-6. Visually confirmed solenoid expands and contracts outside of IACV
3. Unplugged both engine mounts as I don't know what state they are in and I don't wish to replace them
I did the IACV relearn via removing the TPS (brown plug) method. That brought the idle down to about 580 RPM. Much too low for the 700 RPM +/- 50 RPM spec and automatic should have. At this idle speed, stop and restart of the engine within 10-15 seconds results in a stall as the RPM is too low. If i wait longer, it holds at about 580-600 RPM. If I turn on the A/C it drops to about 500 and the car vibrates. A/C fails to cool the car (sounds like it's disengaging the compressor because there isn't enough RPM). P0505 pops up after about 10-15 miles of driving.
If I adjust the throttle body screw (yes, I know it shouldn't be adjusted but found this out after the fact) to get it 700 RPM with no accessories or A/C on, it holds well, drives well, and no stalls after immediate restart. A/C works flawlessly. But after about 100 miles P0505 pops back up. On a cold start it does idle high for awhile but after 20-30 mins it does go back to 700 RPM.
I found the procedure to calibrate the TPS. So with the throttle body out of the car, I used a thin feeler gauge as described to position the throttle screw to its max position but still register continuity on the throttle closed sensor. I tighten the screw at this point. A thicker feeler gauge showed open circuit on the throttle closed sensor. I put it back in and the car is back at idling at 580-600 RPM. IACV relearn does not help. Also note with the throttle screw set to 700 RPM, the throttle closed sensor does not show continuity.
I'm thinking adjusting the screw back to 700 RPM and then taking the throttle body out and re positioning the TPS so that it show continuity on the throttle closed sensor. This is described in the TPS calibration sheet in the service manual. Would this possibly work? Would idling at the correct RPM (700 +/- 50 RPM) but the throttle closed sensor open throw a P0505 or something other code?
What exactly throws a P0505? Is it because the RPM is below 650 or greater than 750 at idle for a certain amount of time? Is there anything else that can throw P0505?
Note that I'm using an ODB-2 scanner to get RPM readings, not the tachometer so these numbers are accurate.
1. Replaced STA509A and confirmed all traces are good on the circuit board
2. Using a genuine Nissan IACV. Confirms 22 Ohms between pins 1-2, 2-3, 4-5 and 5-6. Visually confirmed solenoid expands and contracts outside of IACV
3. Unplugged both engine mounts as I don't know what state they are in and I don't wish to replace them
I did the IACV relearn via removing the TPS (brown plug) method. That brought the idle down to about 580 RPM. Much too low for the 700 RPM +/- 50 RPM spec and automatic should have. At this idle speed, stop and restart of the engine within 10-15 seconds results in a stall as the RPM is too low. If i wait longer, it holds at about 580-600 RPM. If I turn on the A/C it drops to about 500 and the car vibrates. A/C fails to cool the car (sounds like it's disengaging the compressor because there isn't enough RPM). P0505 pops up after about 10-15 miles of driving.
If I adjust the throttle body screw (yes, I know it shouldn't be adjusted but found this out after the fact) to get it 700 RPM with no accessories or A/C on, it holds well, drives well, and no stalls after immediate restart. A/C works flawlessly. But after about 100 miles P0505 pops back up. On a cold start it does idle high for awhile but after 20-30 mins it does go back to 700 RPM.
I found the procedure to calibrate the TPS. So with the throttle body out of the car, I used a thin feeler gauge as described to position the throttle screw to its max position but still register continuity on the throttle closed sensor. I tighten the screw at this point. A thicker feeler gauge showed open circuit on the throttle closed sensor. I put it back in and the car is back at idling at 580-600 RPM. IACV relearn does not help. Also note with the throttle screw set to 700 RPM, the throttle closed sensor does not show continuity.
I'm thinking adjusting the screw back to 700 RPM and then taking the throttle body out and re positioning the TPS so that it show continuity on the throttle closed sensor. This is described in the TPS calibration sheet in the service manual. Would this possibly work? Would idling at the correct RPM (700 +/- 50 RPM) but the throttle closed sensor open throw a P0505 or something other code?
What exactly throws a P0505? Is it because the RPM is below 650 or greater than 750 at idle for a certain amount of time? Is there anything else that can throw P0505?
Note that I'm using an ODB-2 scanner to get RPM readings, not the tachometer so these numbers are accurate.
Idk about it throwing codes unless V is too low or high at idle. As long as it doesn't go out of range, I think it would be fine.
Last edited by Child_uv_KoRn; 07-21-2016 at 04:42 PM.
07-25-2016, 06:45 AM
#4
http://boredmder.com/FSMs/Nissan/Maxima/2001/
p0505 diagnostic is in EC section, starting on page 430 for the 2001
http://boredmder.com/FSMs/Nissan/Maxima/2001/EC.pdf
i'm curious what the solution to this is so am subscribing to this thread, keep us updated if you get it figured out
08-11-2016, 01:51 PM
#5
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Thread Starter
Join Date: Feb 2009
Posts: 6
So I did what I described in my first post. Adjusted the screw to 700 RPM and readjusted the TPS sensor to read closed. Fortunately for me (and unfortunately for the thread), I sold the car days after so I didn't have it long enough to see if the code popped back up. In the short time I did have it the light stayed off and I never saw the code pop up under "Possible Code" on my ODB2 reader. I also never heard back from the buyer so perhaps all is good?
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