Cadillac Repair: High RPMs on an 89 Eldorado, rpms increase, vacuum leaks

Question
QUESTION: Hello,
Ive recently purchased an '89 Eldorado with a 4.5L engine. I bought it on the cheap since it had blown head gaskets. Those were replaced about a month ago by a professional.

I drove the car for about 100 miles and now I have a new problem.

When I start the car, it idles at the normal range. However, after it warms up it continues to increase the RPMs on the engine. In Park it will idle at 2000 RPMs.

This is particularly scary when driving since it makes braking more difficult since the car operates as though I have the foot on the gas at all times. I've stopped driving it for safety reasons and was hoping that you might be able to help me diagnose the problem so that I can maybe fix it myself. I dont really have the money to take it to the nearest mechanic pay for them to fix it - especially since I suspect that my last mechanic is at fault for this.

I've read online that similar people have Vacuum Leaks, causing similar problems. I've also read that it could be the Idle Speed Actuator that has failed.

Im not conviced it is the Vacuum Leak because the High RPMs increase steadily and maintain a high and steady rate. Also... the idle speed is different when in Drive and in Park so maybe it's the transmission?

One interesting thing that got me hoping it was an electrical problem was that when I turn on the A/C the RPMS instantly drop to, and stay at, around 1800 RPMs.

Do you believe that it is the transmission, the Idle Speed Actuator, a Vacuum Leak or even a dirty Throttle Body?

Please help! I'm broke and I dont know much about cars!
This is my first car and it's really heartbreaking to have it break after 100 miles.

Thank you in advance.

Mario

PS
It is an 89 Eldorado, 4.5L with 101k miles on it. There are no check engine lights or messages that show up and the engine has no problem starting up or shifting gears while driving.

ANSWER: This sounds like an idle speed adjustment problem most likely due to someone manually increasing the idle speed in order to keep the engine running at an idle speed because it would stall due to the blown head gaskets.


Your problem can be resolved.



If you are mechanicaly inclined or know of someone who is, You will need a DIGITAL MULTIMETER, Simple electrical schematics, Test procedures and picture locations of the components within the system that is causing you problems of which can't be done on this website which only allows one picture. I do not have a website so you will have to e-mail: onlineautohelp@msn.com in order to obtain the information.


---------- FOLLOW-UP ----------

QUESTION: Does this mean that the blown head gasket repair was not done correctly? or that they didnt repair my blown head gaskets at all???

ANSWER: No, NO. I am sure the repairs were performed on your vehicle. It is just that there is a problem within the idle speed which we can fix with no major expense. Simply E-mail: onlineautohelp@msn.com so that we can fix this simple problem.

---------- FOLLOW-UP ----------

QUESTION: Unfortunately, I do not have much experience with cars, nor do I have any of the tools to do this kind of work.

I guess I was thrown off that the car was fine, at first, and then all of a sudden had this problem about 100 miles after getting the head gaskets replaced.

I've contacted the repair shop and will try to get them to repair it for free since it seems like it was their mistake to begin with. Am I correct in assuming this? They should have readjusted the idle speed controller, correct?


Answer
You stated: I've contacted the repair shop and will try to get them
         to repair it for free since it seems like it was their
         mistake to begin with. Am I correct in assuming this?
         They should have readjusted the idle speed controller,
         correct?

YES, They should have performed this adjustment after the re[pairs were made. Do NOT let them try and tell you that it is NOT adjustable because it is an electronically controlled idle as this is BULL.

If they do NOT know how to properly perform the several required procedures to properly set the idle speed and don't be afraid to ask them , If they do NOT know the procedures, Do NOT let them make ANY adjustments and let me know and I will provide and guide you thru the procedures.