abad95 Posted October 3, 2007 Report Share Posted October 3, 2007 Just had the Heater Core replaced on my '95 STS and the car idles real high somtimes when at Idle (Standing Still). My first thought was the ISC motor- Idle Learn Procedure. Any thoughts on what else it might be when having the Heater Core replaced? What exactly else is done when this happens? Thanks in advance! Florin Link to comment Share on other sites More sharing options...
Ranger Posted October 3, 2007 Report Share Posted October 3, 2007 My guess is that they disconnected the cabin vacuum supply line, thus creating a vacuum leak. The supply line enters the cabin at the passenger side firewall. Same place as the heater core water lines. Link to comment Share on other sites More sharing options...
BigCat83 Posted October 4, 2007 Report Share Posted October 4, 2007 That's right. If you look at where the interior harness enters the firewall on the passenger side you'll see the vacuum line. If the engine bay (intake manifold) connection is okay remove the inside of the glove box and check the connection at the electrical harness. This is real easy to see - you can't miss it. Link to comment Share on other sites More sharing options...
abad95 Posted October 4, 2007 Author Report Share Posted October 4, 2007 Thank You very much Ranger and BigCat ! I will check this out first thing in the morning. Florin Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 4, 2007 Report Share Posted October 4, 2007 Good Idea Ranger and BigCat, yes there are a bunch of vacuum hoses on that side if the engine near the firewall that connect to engine vacuum, the check valve and the vacuum tank under the headlight area. 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...
abad95 Posted October 4, 2007 Author Report Share Posted October 4, 2007 Thank you very much Scotty ! Florin Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 4, 2007 Report Share Posted October 4, 2007 Thank you very much Scotty ! Florin You are welcome, here is a diagram of the vacuum hoses on that side of the engine, #7 connects to the vacuum source on the engine. Those hoses can become brittle, its possible that one cracked, while they were trying to get the inlet and outlet hoses off the core, its very tight in that area. 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...
abad95 Posted October 4, 2007 Author Report Share Posted October 4, 2007 Thanks again Scotty! I have the Helms Manual for the car,but couldn't find anything on the heater core,unless I didn't look good enough. Thanks again for the diagram. Florin Link to comment Share on other sites More sharing options...
abad95 Posted October 5, 2007 Author Report Share Posted October 5, 2007 I checked for vaccum leaks,and didn't come up with anything. I forgot to mention that this happens when the car is hot (Idles higher,and takes forever to come down). The more I think about it,It actually feels like Surging Instead. Do you guys think it might be a coil or a bad connection to the coil pack? I think I hear some sort of zapping sound coming from the coils. What are the posibilities.Could it just be a coincidence that this happened after the Heater core replacement? Thanks for the input in advance...! Florin Link to comment Share on other sites More sharing options...
BigCat83 Posted October 5, 2007 Report Share Posted October 5, 2007 Could be the coil packs, sounds like a vacuum leak too - as the part/hose leaking gets hot and expands the leak worsens. Check the rubber boot that goes from the airbox to the throttle body. There could be a split in the accordian section and as the engine gets hot and moves under load that split is opening up. Link to comment Share on other sites More sharing options...
abad95 Posted October 5, 2007 Author Report Share Posted October 5, 2007 Thanks BigCat! I will check that.When I brought it back from the shop,I was getting off the ramp and was barely able to stop. I turned it off,and started it again,only to see that it just got stuck reved up to around 3000-4000rpm's. I was stuck there with my kids and had to push it aside,because I defenitely wasn't going to throw it in gear and screw it up. Wife wasn't too happy,but waited 10 minutes and it lowered a bit. If It's a Vacuum Leak could it be jerking that high? Also if It's a coil,could it be reving Itself higher trying to keep it alive ? Thanks, Florin Link to comment Share on other sites More sharing options...
Ranger Posted October 6, 2007 Report Share Posted October 6, 2007 I don't think that the '95 has the rubber coupler (plenum) between the TB and the manifold that Bigcat is talking about. It does not sound like coils to me. Have you cleaned the TB and checked the ISC motor? Link to comment Share on other sites More sharing options...
Texas Jim Posted October 6, 2007 Report Share Posted October 6, 2007 reved up to around 3000-4000rpm's. Thanks, Florin Florin, I do not believe a vacumn leak would cause it to rev to between 3000 and 4000 RPM. Check the throttle linkage for binding or maybe a missing spring. Check the clearance between the idle speed control plunger and the linkage. Try to pull up on the accelerator pedal to see if it will slow down. This is strange.... that it is revving THAT high. Link to comment Share on other sites More sharing options...
BigCat83 Posted October 6, 2007 Report Share Posted October 6, 2007 I didn't realize it was reving to 3 grand plus. I agree, check the throttle linkage. A thought...is your accelerator pedal getting hung up under the corner of a mat? I had that happen to me once... Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 6, 2007 Report Share Posted October 6, 2007 Clean the throttle body throat and plate, it could be hanging up 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...
UKcat Posted October 6, 2007 Report Share Posted October 6, 2007 Our car did that last year; I don't remember, exactly, the name of the part, but it was a throttle positioning sensor type of thing. I know that's probably not the right name for it, but that was it's purpose. It controlled the throttle cable some how. My "other car" 1968 Pontiac GTO, 400, 4 speed, 366 h.p., matching numbers car *Get well soon, John Force!!!* Link to comment Share on other sites More sharing options...
abad95 Posted October 7, 2007 Author Report Share Posted October 7, 2007 Thanks you guys, I've been messing around yesterday,and today with my brother,and the more I think about it,I think it might just be the Throttle Positioning sensor, which from what I've been reading the last few days is in the ISC Motor. I've had the dealer install one around 88000 Miles. I know have 192000. It might just be time for a new one... I will look for another one, and Install it,and keep trying. I guess One thing at a time... I will keep you guys posted. In the mean time, I can't drive it anymore. It acts up when driven for a while,and especially when turned off,and turned back on.That's when the RPM's sit at 2000-3000. I defenitely can't throw in gear. I'll see what happens. Thanks again! Florin Link to comment Share on other sites More sharing options...
abad95 Posted October 8, 2007 Author Report Share Posted October 8, 2007 After fixin' some little vacuum leaks, I checked the ISC motor which checked out fine, I also cleaned the throttle body which in the end turned out to be the biggest problem if not the actual problem. Wish I would of done it before al this.Thing is I've done it not too long ago. The thing is that the car sat for a while before having the Heater Core replaced. Thank God I didn't scream at the people at the shop. Ranger,BodyByFisher you were right. Thanks for all you guys help.I defenitely learned a lot from this experience. Florin Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 8, 2007 Report Share Posted October 8, 2007 Glad you got it fixed.. 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...
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