Throttle Position Sensor?

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I got in my 2000 Taurus SE Friday for the drive back from the coast (outside temp around 35F and the car didn't want to start. It cranked just fine but
acted like it wasn't getting any fuel. Once I started keeping my foot on the gas, it started but stalled if I let it just idle. It seemed to want to idle between 3-500 rpm; much slower than its normal 1100 cold and 700 warm. I just kept giving it gas while I changed gears from park to drive.
It ran smoothly in cruise the whole way but continued to stall if I stopped at a light without keeping my foot on the gas. Finally, it seemed to start idling correctly after about 4 hours worth of mostly highway driving.
I'm curious what the problem is. Obviously, I've got to get it fixed but it's running OK right now. I don't expect that to last though...
Ideas?
--
Mortimer Schnerd, RN

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AIC valve.
"Mortimer Schnerd, RN" wrote:

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Sharon K.Cooke wrote:

Idle air control?
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Mortimer Schnerd, RN

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Mortimer Schnerd, RN wrote:

My 97 T-bird 4.6 did the same thing and I got the answer from the answer to a post similar to yours. The problem was the Idle Air Control valve. It (on my engine) is mounted right in front and has an electric connection.
It's fairly easy to remove. Remove the electric connection, two bolts and a hose. There is a spring assy and shaft that gets dirty and sticks. I applied some non residue cleaner with a little brush to clean and then blew out with an air hose. It should free up and fix the problem. If you have a manual you can see what it looks like, or maybe do a search of this group for more input.
Frank
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Do all modern Fords with gasoline engines have this? I don't share the same problem the original poster has written about. Just curious. I'm preparing to do some significant preventative maintenance on my 1998 E-150 Club Wagon. It has about 80K miles on it.

(outside
but
on the

idle
I just

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John B wrote:

I would guess that they do but it would be just that, a guess. Backyard Mechanic is likely a better poster for this question.
Frank
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John B opined in

Yep... every port FI engine with a throttle cable. (It goes away with new drive-by-wire) Easy to find, it mounts right near the throttle butterfly.
ALong with cleaning the MAF as described elsewhere a good preventive step.
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Sorry, I don't understand. Can the TPS be cleaned? Or are you saying to replace it, period, as a preventative maintenance issue? Is the TPS some kind of mechanical-position-to-electrical-resistance sensor? Like a wiper potentiometer? Messing with that could ruin it...?
MAF? Mass Air Flow sensor? This can be cleaned?
What about the all-important O2 sensor? When should that be replaced? Then there are brushes inside the starter motor. Given that this van gets lots of short-haul trips, those brushes are probably worn out...
Thank you!
"Backyard Mechanic"

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John B opined in

Yes, messing with it definitely could ruin it.. really cant be cleaned, it's a sealed unit.
1. just like a volume control, only higher quality. 2. look closely, can it be adjusted (mounting screw slots)?.. dont mess with it, has to be aligned with a dvm. No slots = easy replacement

AND SHOULD BE.... google this group; I posted just a week or two ago

According to parts stores about every 50,000 or three years.
According to my empirical results, when the lite comes on (and relevant codes) or mileage/performance drops... which is to say I've replaced them - with no discernable improvement- but never had one fail in more than 9 different cars in 15 years.
And I've got three cars in my driveway with over 180,000 miles and none are getting less than sticker mileage with no performance faults.
Starter brushes, yep; dont forget the solenoid contactor at same time,
Also Alternator rehab with new brushes... usually easy.
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Backyard Mechanic wrote:

I'm getting lost here. We have the "idle air control" and the "air bypass valve" and now we're talking TPS "throttle position sensor." Are all three the same?
Frank
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F.H. wrote:

No. I initially opined that my symptoms were possibly caused by a bad TPS. I was told that it was more likely a bad idle air control... which ended up being correct. Air bypass valve and idle air control are the same thing; the TPS is something else entirely.
It threw me off as well. That's part of the reason I ended up paying someone to fix my car. I knew I didn't know enough about the fuel system to diagnose and repair the problem without potentially creating many more. I'm good about doing that.
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Mortimer Schnerd, RN

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FWIW, I once owned a 1984 Mercury Topaz. In about 1991, with some 110 K miles on it, the TPS went out. I discovered I had a problem when I flunked a California smog test. I had way too much CO coming out of the tail pipe. I took the car to the dealer for diagnosis. The technician allowed me to be with him while he trouble-shot the problem. There we were, with our two head under the hood. He wanted to change everything, including the car's computer. Fortunately, I was able to stand in there with him and fault his analysis. In the end, we found the TPS to be bad, and replacing that solved the problem.

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John B wrote:

My old '89 Taurus had the TPS go out once. That time, it idled all over the place. This time, it's much more consistent.
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Mortimer Schnerd, RN

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On Mon, 29 Nov 2004 03:11:28 GMT, "Mortimer Schnerd, RN"

Recently encountered same problem w/wife's 2000 Sable w/3.0L engine. New IAC fixed it right up. You can probably clean your old one by soaking the valve portion overnight in a good fuel system solvent. New uints are about $85US from dealer. I found they are in short supply in the aftermarket here in Atlanta, GA area and almost as expensive as the real McCoy from the dealer unless you go to one of the real el cheapo parts places.
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lugnut wrote:

I took it to the dealer today. It was the air bypass valve, according to them. In any case, it's now been replaced and so far things seem to be good. Time will tell if they got it right, given that the problem was intermittent.
Thanks to everyobdy who offered advice....
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Mortimer Schnerd, RN

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Mortimer Schnerd, RN wrote:

Also known as: Idle Air Control Valve. How much did they charge (if you don't mind my asking?) And was there a charge to diagnose?
Frank
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F.H. wrote:

$268
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Mortimer Schnerd, RN

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Mortimer Schnerd, RN wrote:

Ouch! There's another chunk of $$ this news group saved me.
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On Wed, 01 Dec 2004 04:31:04 GMT, "Mortimer Schnerd, RN"

Unfortunately, this is a repair that you could have done yourself for less than $100US in dealer OEM parts and a couple of readily available cheap tools with less than 10 minutes of your time as it is right there in the open on top of the engine. But, then again, the dealer has to make a living somehow. The problem you were having will rarely set a fault code and it will usually work fine when ambient temps are warm emough that you do not notice the cold idle is too low.
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lugnut wrote:

I am well aware I made somebody's car payment for them. I am also aware I could have easily swapped out the parts. If it had been a bad alternator or battery I'd have done that in a heartbeat. When it comes to stuff like this though, I recognize I don't really know what I'm doing. What I didn't want to do was get into the mode of swapping parts with a breakdown between each new part change. It was worth it to me just to have my car be fixed reliably. If I screwed something up and the car wouldn't start, I'd have had the additional fee of towing to pay.
When I asked the group for advice, it was basically so I would know if the repair guys were trying to blow smoke in my face. They didn't, and I'm thankful for the advice that I got here. Even if it did cost me $268 to get my car fixed....
It was cold this morning and yet it started up just like when it was new. I'm satisfied.
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