Jan Olsson Posted February 20, 2009 Report Share Posted February 20, 2009 I've recently encountered occasional high idle rpms. Often around 1200-1300 rpms at idle (neutral) and once 2000 rpms... The throttle body is clean as a whistle. Cleaned the IAC-valve and the air passage. No codes. The throttle blade moves freely to the stopping screw. I think it is the IAC-valve. Any thoughts? Link to comment Share on other sites More sharing options...
BodybyFisher Posted February 20, 2009 Report Share Posted February 20, 2009 Well its a 2002 so I dont think that your throttle body is worn out and binding, how is the cable?, binding at all?. And if the throat is clean and the throttle plate is clean its not hanging open. Plus you cleaned your IAC. My 96 gets a high idle after a long trip and its related to the gunk on the back of the plate that comes to the edges of the plate, once I clean it its fine. I trust you are not getting an LEAN codes right? Your year has that rubber plenum between the throttle body and the intake correct? If no lean problems I would assume that your IAC is bad or hanging up. Check the O ring on it also to see if its leaking air, but that would give you a lean code. We recently had a member with a bad IAC.. 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 Link to comment Share on other sites More sharing options...
Jan Olsson Posted February 20, 2009 Author Report Share Posted February 20, 2009 Well its a 2002 so I dont think that your throttle body is worn out and binding, how is the cable?, binding at all?. And if the throat is clean and the throttle plate is clean its not hanging open. Plus you cleaned your IAC. My 96 gets a high idle after a long trip and its related to the gunk on the back of the plate that comes to the edges of the plate, once I clean it its fine. I trust you are not getting an LEAN codes right? Your year has that rubber plenum between the throttle body and the intake correct? If no lean problems I would assume that your IAC is bad or hanging up. Check the O ring on it also to see if its leaking air, but that would give you a lean code. We recently had a member with a bad IAC.. No codes at all. No binding. The adjustment screw rests against the throttle stop when pedal is released. Link to comment Share on other sites More sharing options...
BodybyFisher Posted February 20, 2009 Report Share Posted February 20, 2009 Well its a 2002 so I dont think that your throttle body is worn out and binding, how is the cable?, binding at all?. And if the throat is clean and the throttle plate is clean its not hanging open. Plus you cleaned your IAC. My 96 gets a high idle after a long trip and its related to the gunk on the back of the plate that comes to the edges of the plate, once I clean it its fine. I trust you are not getting an LEAN codes right? Your year has that rubber plenum between the throttle body and the intake correct? If no lean problems I would assume that your IAC is bad or hanging up. Check the O ring on it also to see if its leaking air, but that would give you a lean code. We recently had a member with a bad IAC.. No codes at all. No binding. The adjustment screw rests against the throttle stop when pedal is released. I would try a new IAC, if you have difficulty getting one, let me know 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 Link to comment Share on other sites More sharing options...
Jan Olsson Posted February 20, 2009 Author Report Share Posted February 20, 2009 Well its a 2002 so I dont think that your throttle body is worn out and binding, how is the cable?, binding at all?. And if the throat is clean and the throttle plate is clean its not hanging open. Plus you cleaned your IAC. My 96 gets a high idle after a long trip and its related to the gunk on the back of the plate that comes to the edges of the plate, once I clean it its fine. I trust you are not getting an LEAN codes right? Your year has that rubber plenum between the throttle body and the intake correct? If no lean problems I would assume that your IAC is bad or hanging up. Check the O ring on it also to see if its leaking air, but that would give you a lean code. We recently had a member with a bad IAC.. No codes at all. No binding. The adjustment screw rests against the throttle stop when pedal is released. I would try a new IAC, if you have difficulty getting one, let me know Is there a possibility that the TPS could be acting up since I didn't get any codes? Maybe it is the TPS acting funny? I've checked the price for a IAC..ouch. Im planning on getting one from a junkyard. If I don't have any luck finding one I let you know! Link to comment Share on other sites More sharing options...
BodybyFisher Posted February 20, 2009 Report Share Posted February 20, 2009 I was reading the FSM yesterday and it stated that if there were any anomalies in the TPS that it would set a code. 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 Link to comment Share on other sites More sharing options...
Jan Olsson Posted March 1, 2009 Author Report Share Posted March 1, 2009 Hmm. I finally got my hands on a used IAC-valve! I also had discovered a vacuum leak on the thing mounted on the top of the intake hose (only one 2" connection and no electrical connection...wonder what it's for?) Today I cleaned the EGR-valve and the air passage for the IAC. The throttle body looked allright. I changed the IAC and the plastic thingy on top of the air filter assembly, disconnected the battery for 10 minutes and everything seems to work as it supposed to except from that the idle was a steady 900 rpms. I figured it would settle down with time and drove wifey to her work, put gear in park to discover that idle took a jump to 1300 rpms when the AC engaged. After turning engine off and restarting it the idle was a steady 700 rpms. No codes, no sticking accelerator cable. My thoughts is that if the car recognizes that the idle is too high it would determine it from the TPS since there is an IAC and not an ISC on my car. If the TPS is alright then the car wants the idle to be high for some reason..hmm. It can not be a vacuum leak since it is intermittent..MAF or PCM? Im going to wash my baby now and check the idle once again! Link to comment Share on other sites More sharing options...
adallak Posted March 1, 2009 Report Share Posted March 1, 2009 The problem may be also purely electrical. Bad grounds, bad contacts between the PROM and PCM, bad PCM contacts, grounds. All this stuff can cause idle surges. The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
Jan Olsson Posted March 1, 2009 Author Report Share Posted March 1, 2009 The problem may be also purely electrical. Bad grounds, bad contacts between the PROM and PCM, bad PCM contacts, grounds. All this stuff can cause idle surges. Good point. Link to comment Share on other sites More sharing options...
Ranger Posted March 1, 2009 Report Share Posted March 1, 2009 I also had discovered a vacuum leak on the thing mounted on the top of the intake hose (only one 2" connection and no electrical connection...wonder what it's for?) That may cause a high idle unless you fixed it. Link to comment Share on other sites More sharing options...
BodybyFisher Posted March 1, 2009 Report Share Posted March 1, 2009 Got Codes? 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 Link to comment Share on other sites More sharing options...
Jan Olsson Posted March 2, 2009 Author Report Share Posted March 2, 2009 I also had discovered a vacuum leak on the thing mounted on the top of the intake hose (only one 2" connection and no electrical connection...wonder what it's for?) That may cause a high idle unless you fixed it. Vacuum leak is fixed. Intermittent high idle. Somtimes perfect at 700 rpms and somtimes like this morning 950 rpms. Link to comment Share on other sites More sharing options...
Jan Olsson Posted March 2, 2009 Author Report Share Posted March 2, 2009 Got Codes? No codes at all. Link to comment Share on other sites More sharing options...
Jan Olsson Posted March 2, 2009 Author Report Share Posted March 2, 2009 Im interested about how the system controls the idle speed with my setup. Any FSM? Link to comment Share on other sites More sharing options...
adallak Posted March 2, 2009 Report Share Posted March 2, 2009 I also had discovered a vacuum leak on the thing mounted on the top of the intake hose (only one 2" connection and no electrical connection...wonder what it's for?) That may cause a high idle unless you fixed it. Vacuum leak is fixed. Intermittent high idle. Somtimes perfect at 700 rpms and somtimes like this morning 950 rpms. 700 RPM is too high for a fully warmed up engine. The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
Jan Olsson Posted March 2, 2009 Author Report Share Posted March 2, 2009 I also had discovered a vacuum leak on the thing mounted on the top of the intake hose (only one 2" connection and no electrical connection...wonder what it's for?) That may cause a high idle unless you fixed it. Vacuum leak is fixed. Intermittent high idle. Somtimes perfect at 700 rpms and somtimes like this morning 950 rpms. 700 RPM is too high for a fully warmed up engine. The old IAC gave me 650 rpms occasionally. More often 700-800 rpms. Gear in park. I'm going to spray all throttle body contacts with WD-40. It might just be that one of the cables/contacts on one of the throttle body electrical components has a bad connection. I suspect this since the idle always acted different every time I had the IAC away for cleaning, change etc. Link to comment Share on other sites More sharing options...
BodybyFisher Posted March 2, 2009 Report Share Posted March 2, 2009 The IAC has a tiny o-ring on it, make sure yours is in place or you will suck air from there, not sure if that can cause your problem but its a guess. Check the TB o-rings. I would change them all, if you want Ill send them to you 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 Link to comment Share on other sites More sharing options...
Jan Olsson Posted March 4, 2009 Author Report Share Posted March 4, 2009 The IAC has a tiny o-ring on it, make sure yours is in place or you will suck air from there, not sure if that can cause your problem but its a guess. Check the TB o-rings. I would change them all, if you want Ill send them to you I finally found the problem! It was a bad connection at the MAP sensor..I just disconnected it and reconnected it..voila! This weekend I'm planning on cleaning contacts in the engine compartment... Well at least I have an IAC-valve extra in case of future problems Idles just under 700 rpms with gear in park! Smooth operation from the tranny too! On the other hand I got "Service electrical system" and the TC-light lit up..cruise control didn't work either. I discovered that not one but BOTH the brake-light bulbs had burned out.. I regulary check the lights but the brake lights are hard to see if you're not backing up against a wall or a mirror. I changed them and everything worked as it should afterwards...phew Link to comment Share on other sites More sharing options...
BodybyFisher Posted March 4, 2009 Report Share Posted March 4, 2009 I am surprised it did not set a code 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 Link to comment Share on other sites More sharing options...
Jan Olsson Posted March 5, 2009 Author Report Share Posted March 5, 2009 I am surprised it did not set a code Me too. I should have got a code about the high idle at least. Well I'm sure a doze of WD40 this weekend will do the trick. Car runs perfekt now or at least better than ever Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.