Rev engine unstable when engine hot?

DIDIER KATZ

MEMBER
1996 CADILLAC ELDORADO
4.2L
V8
2WD
AUTOMATIC
40,000 MILES

Hi,

As mentioned, the car gets dangerous when the engine gets to the normal temperature.

A° As long as the engine is cold, it runs quite okay.

But,

B° When getting a normal temperature for its use, the engine goes wrong :

It goes up and down, but never stays stable.

when, and it does, happen when running, then if at low speed the engine stops : therefore the car is not drivable : loss of the assisted wheel system

Let me know where to a) check, and b) to change a temperature sensor, if this is the possible reason.

I count on you to explain to me in :
- simple and clear sentences,
- English is not my mother tong,
- I will then have to translate to a mechanic in French.

Thank you for your help.

Best,

Didier

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
42,940 POSTS

Hello Didier,

It sounds like the IAC control is not working correctly, do you have a check engine light on? We should run the codes to see what comes up, here is how to get the codes.

The unit indicates an ERR in the VF display if the focusing mechanism is impaired by moisture, or if tracking or servo problems occur, or if a disc is inserted upside down. The unit switches to the radio mode and ejects the CD. The ERR remains lit in the VF tube for 5 seconds, along with the normal information.

If a CD is inserted upside down, the CD player is not able to initialize, and the unit will not shift into the audio modes; ERR is lit in the VF display and the disc ejects. The ERR graphics turn off after 5 seconds or if the disc is reinserted correctly.

ERR is not lit unless the CD player is active and in the play mode, or if the ambient temperature exceeds a preset temperature and the CD operation is either not functional or in jeopardy of damaging the laser. The disc ejects and ERR lights in the VF tube. The ERR is maintained in the VF display until the temperature changes to a safe operating temperature. While ERR is displayed the unit does not accept a disc.

NOTICE: Audio unit codes appear on the radio VF display automatically and are cleared by correcting the cause of the code.

Here is the IAC motor so you can change it out. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem.

Images (Click to make bigger)