racing Idle problem 96 taurus

When I start my car the engine races.I will have to wait about 5 minutes and it will drop a little..As I start driving the idle surges high again and I have to stop and turn the car off then restart...wait for the idle to go down .sometimes its fine and other times it happens again? and again Help..someone said it could be the terpentine belt? Is that possible
Thanks for any help

Welcome to the forum!

The serpentine belt should have no effect on the idle speed, unless it was slipping and not allowing the alternator to charge. If that were the case, you'd have other symptoms I expect.

The first thing I'd check would be the throttle plate. You may have enough carbon built up on it that it's not able to fully close some times.

You'll also want to consider the Idle Air Control (IAC) motor. Try turning on the A/C or defrost with the car idling. Does the engine speed drop or remain pretty constant whent he A/C compressor engages? If it drops, or races, then your IAC could be the likely culprit.

You can also check out the Throttle Position Sensor (TPS), make sure it's response is linear according to a multimeter or scan tool with datastream. There are a lot of sites that go into detail on testing the TPS so I won't duplicate that text here.

And then there's the EGR valve. Although if it's sticking partially open, I'd expect you'd have moments of rough idle preceeding the fast idle. Same if you had a vacuum leak (or intake air tubing leak).

I suppose a faulty coolant temperature sensor could contribute to this, but I'd expect it to not be remedied by a restart of the car. The IAC will be reset with the restart.

-Rod

Thanks rod
Its not the serpentine belt..no other problems
When I started the car I put the air conditioning on like you said to do. The idle went down and up once high and then down again & pretty much stayed kinda steady.
I don't think I have a vacuum leak because the car is not idling rough at all.

Usually when I start the car it runs a lil high..if I put my foot on the break it races higher or if I don't sit and let the car warm up somewhat when I start driving I don't even have to put my foot on the gas..its moves itself.When I go to break when driving the car races like it does not want to stop.Its been doing this for a while now and getting worse..
I had my fluids changed etc and told the guy and he said to change the serpentine belt..but I questioned that. I hate getting ripped off
I will check out he Idle Air Control (IAC) motor..where should I go to get this done..a mechanic or can I have it checked out at an auto supply that has the gadget to check..Sorry not into autos so I don't know much
Thanks Carol

You also mentioned the coolant temp thing..My temp gauge in the car I noticed it would go up and then drop down significantly.I thought something was wrong with it? a few times when I started the car it would be all the way up?

Your car has a separate coolant temperature sending unit for the guage and an engine coolant temperature sensor for the PCM, so the gauge and PCM temps would be unrelated unless there is a cooling system problem. From what you describe, it almost sounds like you might have an air pocket in the cooling system as well.

The IAC is typically pretty easy to change out. It's usually easy to access and held on with two 10mm bolts. There's one wiring connector that will need to be unplugged. There's also a steel gasket between the IAC and the throttle body. The parts stores won't be able to check out the IAC with a scan tool or even on the bench unless there is a set diagnostic code for it. It does sound like yours is slow to respond, but that could be partially due to a build up of carbon as well. If you or an acquaintance are fairly mechanically inclined and have a 10mm socket wrench, you should be able to avoid a trip to a shop to at least clean the IAC, passages, and throttle plate.

I'd certainly suggest cleaning the back side of the throttle plate while working in the area of the throttle body and looking as far into the upper intake manifold as you can. If it's pretty carboned up, you might want to perform a cylinder decarb using a can of SeaFoam and well ventilated area. If just the throttle plate has carbon, then get a can or two of STP Throttle Body Cleaner and spray off the throttle plate. This cleaner will also work well for cleaning out the IAC and passages, as well as the EGR valve is you later decide to pull it and clean.

-Rod

I have the same problem with my '07 Taurus. My mechanic just confirmed that it's the throttle position sensor. I was wondering what the difficulty level is for replacing one of these for someone that is pretty "mechanically inclined", but never replaced one??!!

Very straightforward, two screws and a 3-wire electrical connector. It's installed on the throttle body. You can view a photo of it by application on the Advance Auto Parts website. They run about $25 after tax there.

-Rod