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Idle Speed High Code P0507


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I am getting the P0507 code (Idle Speed High) every since I cleaned the Throttle Body and IAC unit. I have taken it apart twice and checked everything out and replaced it and still throw the code whenever the car sits and idles for long enough period of time. The car is idling at 800 rpm and I heard it is supposed to idle around (500-600). I don't remember where it idled before this started happening. The IAC seems to be working fine because it does make a differnece when unplugged and then plugged back in. When the car is first started the idle goes from around 1100 down to 800. But it will not go any further down than that. The throttle body is completely closed as far as I can tell and I don't hear any vacuum leaks.

Does anyone know what I can do to get it to idle lower and stop throwing the code?

Today is the day you were worried about yesterday!

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Hmm; here is the link from the How-To but this procedure was for the 4.9L; I'll have to ask others to confirm that the process is the same/similar for the Northstar, or detail the NS process.

Bruce

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LINK PLEASE!

I tried searching and found nothing.

Here ya go.

http://www.caddyinfo.com/idlelearn.htm

I'm quite sure this is the one Bruce was talking about, but as he mentioned this is for the 4.9 engine. The procedure may differ for the Northstar.

I cleaned my throttle body and my Idle Speed Control Motor, and didn't seem to have any issues related to those afterward, and I never performed the Idle learn procedure. Then again, I also didn't have a high idle code either. I'll see if I can find anything on one for the N*. If I do I will post it here.

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I would imagine that the 94 has an idle learn procedure, as it has an ISC motor. I would first disconnect the battery and see if it does a relearn on its own. Have you disconnected the battery since doing the work?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I would imagine that the 94 has an idle learn procedure, as it has an ISC motor. I would first disconnect the battery and see if it does a relearn on its own. Have you disconnected the battery since doing the work?

I did, yes.

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I called my father and had him look in his service manual, and according to that, the Idle learn procedure for the 4.9 is the same for the 4.6 N* from 1993 to 1999. I'm not sure about anything after that, as he doesn't have a manual for anything newer than that.

PS, thanks to whoever corrected my first post. Oops.

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I would imagine that the 94 has an idle learn procedure, as it has an ISC motor. I would first disconnect the battery and see if it does a relearn on its own. Have you disconnected the battery since doing the work?

I did, yes.

I was asking that question of badrhino, as he is having the high idle problem after cleaning his TB

From 96 forward there is no idle learn procedure all you need to do is disconnect the battery

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I would imagine that the 94 has an idle learn procedure, as it has an ISC motor. I would first disconnect the battery and see if it does a relearn on its own. Have you disconnected the battery since doing the work?

I did, yes.

I was asking that question of badrhino, as he is having the high idle problem after cleaning his TB

From 96 forward there is no idle learn procedure all you need to do is disconnect the battery

My apologies. His model year is listed as 99, mine is a 94, so I thought it was directed at me. My mistake.

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BodybyFisher, no I have not tried disconnecting the battery. I will try that tomorrow and report what happens. Thanks!

Some other suggestions from another site said to but the car in reverse with brake on and set there for about 10 minutes to relearn the idle but I tried that and it did not work. :fighting0025:

Today is the day you were worried about yesterday!

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What happens is, as the throttle body gets dirty, the IAC compensates by allowing more air, when you clean the TB, you must 'reboot' or relearn the proper IAC point, right now, you are getting too much air causing your racing idle. I am pretty confident disconnecting the battery will force a relearn and you will be ok. let us know, Mike

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Mike,

I disconnected the battery for about 5 mins. and hooked it back up. Started the car and idle went to 1,200 and then back to 800 rpm. I still can not get it to go lower than that. Even in gear at a stop the idle is around 700 or so. Any other thoughts? Ryan

Today is the day you were worried about yesterday!

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....Even in gear at a stop the idle is around 700 or so. Any other thoughts? Ryan

The critical part of cleaning your year/model throttle valve is the edge or perimeter of the blade and the area where the blade meets the bore of the throttle body when the throttle is closed. Both areas must be surgically clean to allow the blade to seal which puts the IAC in control of air flow at idle.

If you are satisfied that the blade and the bore are clean, the next best suspect would be the Throttle Position Sensor (TPS) located on the front surface of the throttle body. Check the electrical connector; if all "appears" in order, I would remove the TPS and test the sensor rotation from stop to stop paying attention to the "feel" of movement. It should be smooth and consistent throughout the entire travel and in particular at the closed-throttle position.

Good luck.

Jim

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CHOOSE ONE !

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Mike,

I disconnected the battery for about 5 mins. and hooked it back up. Started the car and idle went to 1,200 and then back to 800 rpm. I still can not get it to go lower than that. Even in gear at a stop the idle is around 700 or so. Any other thoughts? Ryan

Make sure that when you cleaned the TB that you cleaned the throat and edges of the throttle plate very good and that the TB plate closes fully and nothing is hanging it open

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Mike,

I disconnected the battery for about 5 mins. and hooked it back up. Started the car and idle went to 1,200 and then back to 800 rpm. I still can not get it to go lower than that. Even in gear at a stop the idle is around 700 or so. Any other thoughts? Ryan

I'm no expert, so don't take my word for gold, but I've had idle problems with my car in the past. I believe normal idle in park or when at a stop is 600-700 rpm, so that sounds right to me. As far as it going up to 1,200 when you start it, if it's cold out, I believe that's normal as well. If not, then maybe after you drive it a few times it will adjust itself. It took a couple times driving it after I cleaned the ISC motor and throttle body before my idle went back to normal. As I said, I'm no expert, just sharing my experience in hopes that it may help you.

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Mike,

I disconnected the battery for about 5 mins. and hooked it back up. Started the car and idle went to 1,200 and then back to 800 rpm. I still can not get it to go lower than that. Even in gear at a stop the idle is around 700 or so. Any other thoughts? Ryan

I'm no expert, so don't take my word for gold, but I've had idle problems with my car in the past. I believe normal idle in park or when at a stop is 600-700 rpm, so that sounds right to me. As far as it going up to 1,200 when you start it, if it's cold out, I believe that's normal as well. If not, then maybe after you drive it a few times it will adjust itself. It took a couple times driving it after I cleaned the ISC motor and throttle body before my idle went back to normal. As I said, I'm no expert, just sharing my experience in hopes that it may help you.

The 99 does not have an ISC motor, it has an IAC. There were many changes from OBD1 to OBD2 and from year to year, I have purchased manuals for 91, 95, 96 for the purpose of understanding the different systems. The next manual that I purchase will be 2000

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Mike,

I disconnected the battery for about 5 mins. and hooked it back up. Started the car and idle went to 1,200 and then back to 800 rpm. I still can not get it to go lower than that. Even in gear at a stop the idle is around 700 or so. Any other thoughts? Ryan

I'm no expert, so don't take my word for gold, but I've had idle problems with my car in the past. I believe normal idle in park or when at a stop is 600-700 rpm, so that sounds right to me. As far as it going up to 1,200 when you start it, if it's cold out, I believe that's normal as well. If not, then maybe after you drive it a few times it will adjust itself. It took a couple times driving it after I cleaned the ISC motor and throttle body before my idle went back to normal. As I said, I'm no expert, just sharing my experience in hopes that it may help you.

The 99 does not have an ISC motor, it has an IAC. There were many changes from OBD1 to OBD2 and from year to year, I have purchased manuals for 91, 95, 96 for the purpose of understanding the different systems. The next manual that I purchase will be 2000

Good point Mike. As I said, I was only speaking from experience, as that is all I really have to speak from at this point. Did the switch from ISC to IAC happen in 96 when the OBD switch happened? Just curious. I'm trying to learn what I can. I like being able to offer a helping hand whenever I can, and learning new things is a good place to start. I've learned a lot from everyone on here already.

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The changes from year to year can be daunting. I tend to take a back seat on years that I am not familiar with as its easy to make a mistake, the intakes, brakes, accessories, engine mounts, suspensions, engine controls, ignition, emission, and even battery and coolant tank placement varies year to year. The Northstar itself was changed in 2000 and 2004 in many ways. Its easy to make mistakes based on our experience, I have a 96 that is a dynasaur compared to anything 2000 and up, and yours it totally different than mine. Its quite a challenge

In 96 lots of changes occurred, Dexcool from the factory, OBD2, PCM had more capacity, engine controls changed, but there are lots of year to year changes, but 96 was kind of a big change year.

Many will say that the 94/95 was the most powerful

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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