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Chris (aka- Moose)
Chris (aka- Moose), Cadillac Technician
Category: Cadillac
Satisfied Customers: 44523
Experience:  16 years of experience
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I own a 1997 Cadillac Deville Concours, it has only original

Customer Question

Hello; I own a 1997 Cadillac Deville Concours, it has only original 45,000 miles on it and has run great for three years. Recently it has become dangerous to drive because the RPMs are erratic, RPMs jump up into high numbers and the engine races. I have replaced the TPS throttle position sensor and the IACV idle air control valve, which were supposed to be the common causes. I can't get the car to throw any codes to tell what the problem is and have taken it to two local mechanics, who also say they can't see any codes thrown either and don't know what the problem is. What is your professional opinion of what I should check next? John
Submitted: 11 months ago.
Category: Cadillac
Expert:  Chris (aka- Moose) replied 11 months ago.

Welcome, I'm Chris (aka Moose) I'm an independent contractor here at Just Answer.

Will this occur in neutral or park?

When this occurs are you touching no pedals?

How often does this occur?

Thanks for asking your question and letting me try to help you.

Customer: replied 11 months ago.
Hello Chris;
This occurs in no specific pattern (random), sometimes the car drives fine. This can occur when driving, no foot on the accelerator, car accelerates by itself as the RPMs climb, ignition must be shut off quickly(turn the car off ), this can happen when you shift to neutral, this can happen when driving down the road and this can happen when the car is in park. Again all while no foot is on the accelerator and car must be turned off quickly. I think it goes without saying, but of course one must have a foot pressed firmly on the brake pedal as the car has the ability to go very fast very quick and that of course can be dangerous in heavy traffic.
Expert:  Chris (aka- Moose) replied 11 months ago.

When it has occurred in park were you applying brakes?

Customer: replied 11 months ago.
No, I had a foot over the brake pedal just in case, but the emergency brake was on (depressed) and the car was in park.
Expert:  Chris (aka- Moose) replied 11 months ago.

Thanks, ***** ***** wanting to rule out a vacuum leak in the brake booster, which we did so.

Spray clean the MAF sensor using brake cleaner, then spray and scrub clean the throttle body and bore using brake cleaner and a tooth brush then retest. If it occurs again then you need to replace the PCM.

Thanks for asking your question and letting me try to help you.

If you are unable to rate my response GOOD or EXCELLENT now. Please let me know why ( if I need to help more) and when you will be able to.

Follow up/Reply as many times as needed before or after rating.

Customer: replied 11 months ago.
What is the PCM and where is it located on the engine?
Customer: replied 11 months ago.
Chris;
We asked at 1:26 pm what the PCM is and where it is located. The MAF and throttle body are clean already. We didn't mention that before. Please respond. We are going in and out to the car in the garage of our home, but are trying to watch for your reply.
Expert:  Chris (aka- Moose) replied 11 months ago.

PCM is the powertrain control module. It is under the air filter box.

Expert:  Chris (aka- Moose) replied 10 months ago.

I like to stay in contact with my customers that appear not pleased, still working on the concern, or have not rated yet. I assume you were not pleased with my help. I hate that you have spent money to get an answer but left not happy. Can you tell me why, or can I help more. If its more help you need just reply and we can pick up where we left off.

Thanks Chris