: 94 sls whats causing a high idle?!



starfox86
09-23-05, 07:08 PM
my cars in the shop right now and when it starts up, it shoots up to about 3500rpms...the shop thought it was a vacuum leak because it had a couple craked rubber vacuum pieces...so, they replaced those and now they just cant figure it out why its idleing so high. i read another post saying the it was a dirty throttle body. my engine has about 11000 miles on it, (yes, its a different engine than the original..just the block and heads)...and the engine was clean ,so i wouldnt suspect that to be the problem. could an intake mainfold gasket be the problem? I had a problem putting those 2 plastic parts on the heads that the intake manifold gaskets went on because the little pin that held them in place on the heads were broken on both. so I am not sure if they are perfectly inplace.but I have had the engine in for about 2 months and the idle just started acting up.
I guess to retrace my steps, about a month ago, I replace the idle control motor. and the MAP sensor. when I first put both in, the engine did the same thing(high idle). but then i adjusted the idle control motor in a little bit, and that seemed to fix it. and i didnt have a problem with it until now. could a bad seal for the map sensor cause this? maybe I should jus replace the idle control motor again. I dunno ... the mechanic said that theres some kind of vacuum leak and he said i should take it to the dealer to get a diagnostic test for 80 bucks and then have them fix it. but I am pretty sure i cant solve this mistery with your guys help...:bouncy:

mcowden
09-23-05, 11:02 PM
my cars in the shop right now and when it starts up, it shoots up to about 3500rpms...the shop thought it was a vacuum leak because it had a couple craked rubber vacuum pieces...so, they replaced those and now they just cant figure it out why its idleing so high. i read another post saying the it was a dirty throttle body. my engine has about 11000 miles on it, (yes, its a different engine than the original..just the block and heads)...and the engine was clean ,so i wouldnt suspect that to be the problem. could an intake mainfold gasket be the problem? I had a problem putting those 2 plastic parts on the heads that the intake manifold gaskets went on because the little pin that held them in place on the heads were broken on both. so I am not sure if they are perfectly inplace.but I have had the engine in for about 2 months and the idle just started acting up.
I guess to retrace my steps, about a month ago, I replace the idle control motor. and the MAP sensor. when I first put both in, the engine did the same thing(high idle). but then i adjusted the idle control motor in a little bit, and that seemed to fix it. and i didnt have a problem with it until now. could a bad seal for the map sensor cause this? maybe I should jus replace the idle control motor again. I dunno ... the mechanic said that theres some kind of vacuum leak and he said i should take it to the dealer to get a diagnostic test for 80 bucks and then have them fix it. but I am pretty sure i cant solve this mistery with your guys help...:bouncy:


If it's idling high, there is a vacuum leak somewhere. It can't run fast without air, so you'll have to figure out where it's coming from. Yes it could be the intake manifold gasket, and yes it could be cracked hoses and yes it could be a bad seal for the map sensor. It could also be the popoff valve at the end of the intake that's loose or a dirty throttle body or a misbehaving idle speed control motor. Get yourself a piece of hose or a mechanic's stethoscope and listen all around the intake for a hissing. The popoff valve is on the passenger side of the intake, on the end right in the middle. If it's open a little bit, it will need a spring or replacement. Somehow air is getting in the intake when it shouldn't. Just do some sleuthing with a water mister (use sparingly) and something to listen up close and you'll find it sooner or later.

starfox86
09-25-05, 03:32 AM
well, i picked my car up today from the shop expecting it needing a tow to the dealer...i started it up to see what the mechanic was talking about..and it didnt shoot up to 3000 rpms , so, i drove it home (about two blocks)...and when i accelerate, the rpms stay up and the car stays at the speed i ended at until i brake, its quite strang. no engine light, no codes, it almost seems like the tranny isnt shifting. I was getting a shift selonoid code when i brought it in to the shop...but he said it could jus be a vacuum leak. and also, the tempurature rose fast, it stayed around 245, so something is definately wrong. can someone give me all the things to check for over heating?....these are the things i have already done: checked purge line, new radiator, new hoses, new cap, flushed system. could the egr valve cause this?...i thought i read something on how if it was stuck , it would cause over heating. i am almost positive its not the head gaskets, because the engine only has about 12000 miles on it. and it jus started to over heat when the rpm thing started happening.

davesdeville
09-25-05, 08:43 AM
If the EGR valve is stuck it should throw a code (P036.) The shift solenoid code seems to be unrelated to the high idle and overheating. The high idle could be a vacuum leak, but if it's steady it is probably the ISC. The engine doesn't like unmetered air (air from anywhere besides the throttle body) so it usually won't have a steady high idle if there's a vacuum leak like that. As for the overheating I would probably do the head gasket tests.

philipz
09-25-05, 10:56 AM
Hi starfox86,
few mounts ago I have the same problem (high idle) and fix problem by myself - I open ICS and saw broken part in electrical contact which is close when foot is out of throttle. I use iron to fix broken part and problem disappear. I hope this will help you.

mcowden
09-25-05, 01:09 PM
If the EGR valve is stuck it should throw a code (P036.) The shift solenoid code seems to be unrelated to the high idle and overheating. The high idle could be a vacuum leak, but if it's steady it is probably the ISC. The engine doesn't like unmetered air (air from anywhere besides the throttle body) so it usually won't have a steady high idle if there's a vacuum leak like that. As for the overheating I would probably do the head gasket tests.

If the transmission is not shifting into a higher gear as you accelerate, the shift solenoid code you got is probably really a problem. If you're driving it like usual and it's not shifting, you're going to burn up the motor and trans. The overheating is probably caused by running the engine at high RPMs with not enough air moving across the radiator. If it was shifting right, it would run at lower RPMs and would not overheat.

Do this quick test for us: Slowly accelerate up to 45 MPH and hold it at 45 for 10 seconds. What are the engine RPMs at 45 MPH? When you let off the gas, does the car decelerate properly? If the RPMs are above 2000, something is wrong with the transmission. Fix the cause of the high RPMs and it probably won't overheat any more. If you let off the gas and the car barely slows down or the RPMs don't drop as you expect them to, you either have a vacuum leak to the intake somewhere and the shop didn't fix it or the throttle cable is sticking.

Just my thoughts. Sounds like you need to solve some other issues and the overheating will go away on its own.

mcowden
09-25-05, 01:12 PM
Hi starfox86,
few mounts ago I have the same problem (high idle) and fix problem by myself - I open ICS and saw broken part in electrical contact which is close when foot is out of throttle. I use iron to fix broken part and problem disappear. I hope this will help you.

Philipz, welcome to Cadillac Forums! Thanks for posting... There are plenty of knowledgeable and friendly people here. Glad you found us. Let us know if you have any questions or problems and I'm sure you will get the help you need.

:welcome:

starfox86
09-25-05, 07:26 PM
well, i took the intake manifold off today, and im going to replace the 1.5" plastic spacers on monday that the gaskets sit on, the pins on one of them were broke. hopefully its the cause of the vacuum leak... I noticed that the spacers had gas on them. now, if I am not mistaken, there shouldnt be gas on these things. so, what could this be from, a stuck valve? should i spray the valves with a lubracant?...of so what kind?

csbacchus
09-29-05, 07:35 AM
Have you looked inside the throttle body?

"(yes, its a different engine than the original..just the block and heads)"

I had these same symptoms and it was the throttle body. If you replaced the block and heads, are you certain the throttle body was replaced also? It is pretty easy to check if you haven't . Take off the intake hose from the air filter box to the throttle body and open the butterfly with the throttle bracket. If its black in there, you need to clean it.
I know you said the engine only has 11,000 miles, but you should rule out the obvious first if you haven't already.

My symptoms were an even idle when started cold and as the engine warmed up or was driven, the idle would hit about 1500 and then rev to 3500. It was almost like the cruise control was stuck. If started when warm, it was immediately at 3000. Any engine will overheat when it is revved high and not moving. So, check all quick and easy fixes first. Get it fixed quick, though. You don't want to engage the tranny with high revs. It will wear it out.

Also, check to make sure your cables, cruise and throttle, aren't binding anywhere. Have you checked the codes?

Please post if you find a fix. We all like to hear of solutions to these sorts of things.

starfox86
09-29-05, 10:58 AM
i took the intake manifold off and inspected everything, no dirt to be seen. i was very taken back that i couldnt find a trace of dirt. i checked the fuel rails out and the injectors, they looked good. now, i think i found my problem. the idle control motor sticks open when i pull the throttle and it makes the rpms stay around what ever i reved it to. i bought it at advanced auto parts so its not ac delco. i am thinking about jus getting the acdelco from the dealer. i followed sal c's tips in another post about starting the car than reving it to about 2000 and then puching the icm pin in all the way and then pulling the connector out to set it. the pin would not move. it stayed at what i reved it. so, i am thinking the icm is bad, or i didnt set it right in the first place and now its bad, or i have an eletrical problem somewhere making the pin not retract

starfox86
09-29-05, 12:06 PM
alright guys !! I fixed the high idle problem. !!! the icm went bad i guess after a month. I put the old one on there. no more problems!!!!!!!!!...the only thing i am getting is a clicking sound after i turn the car off which i originally replaced it for. but i will live with the clicking for now until i take the car in to the dealer to get it changed-i want it done right. and now im getting a PO94 code, because its staying in 2nd which is a selonoid i believe ..but , hey, its better than the high idle.
Thanks for everyones help