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1986 Cadillac Sedan DeVille, 1998 Cadillac Sedan DeVille
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75 Posts
Discussion Starter #1 (Edited)
Ok, so heres the problem...The accelerator/throttle on my car (1998 Cadillac Deville) will get stuck at about 2200-2700 RPMS...The problem gets worse the more i drive it. It has progressed from me being able to life up on the pedal with my foot and stop it, to not being able to stop it at all.

The mechanic has had the car for three months and couldn't figure out what it was...he replaced the Intake Manifold and Gasket, Idle Air Control, and lowered the idle. Which fixed it for about 2 days.

But today it stuck on the highway about half open, so i had to downshift throught he gears and put it in neutral to stop. Which probably damaged the transmission since i could smell something like tranny fluid roasting. I checked the transmission fluid after it was towed to my mechanic and it seemed to be really low. However, I doubt it was low the entire time since its had this problem before and the mechanic "fixed it" and it ran fine for a day.

So any ideas on what may be causing this.

P.S. I've ruled out the Cruise Control I disconnected it.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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71,095 Posts
There will be NO transmission fluid on the stick with the engine off !!! The transmission is a dry sump unit and must be checked with the engine running, warm, in P, and the fluid adjusted to halfway up the dipstick mark.

I'll bet that the TPS (Throttle Position Sensor) is packing it in.

Read the sticky at the top of the main page entitled "How to pull codes", get to the sequence for OBD-II, write them all down, and see what faults are set. It's all built into the car already - you don't need an aftermarket scanner. Same info down in Cadillac Technical Discussion, Technical Tips, sticky thread at top of the page.
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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6,738 Posts
Could be as simple as the floor mat getting up under the throttle pedal, remove the drivers mat. You say you disconnected the cruise. What did you disconnect? If it was just the electrical connection then take the chain off the servo as well at the throttle body end. If the TPS switch is loose on the throttle body it can rotate and advance the fuel delivery which could raise the idle.
 

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1992 DeVille
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70 Posts
Carnut
I have a 92 DeVille the TPSensor is connected to the throttle body w/ 2 screws. Are these screws supposed to be very tight to keep the TPS from moving? Or is the TPS supposed to move along side the throttle body?
 

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1986 Cadillac Sedan DeVille, 1998 Cadillac Sedan DeVille
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75 Posts
Discussion Starter #6
Could be as simple as the floor mat getting up under the throttle pedal, remove the drivers mat. You say you disconnected the cruise. What did you disconnect? If it was just the electrical connection then take the chain off the servo as well at the throttle body end. If the TPS switch is loose on the throttle body it can rotate and advance the fuel delivery which could raise the idle.
Lol, i assure you its not something as simple as the floormat stuck underneath the accelerator. When I disconnected the cruise control i unpluged the pigtail electrical connection to it. That did help for a little bit with the engine racing off but only seemed to help for a few hours.

I'll bet that the TPS (Throttle Position Sensor) is packing it in
.

I'll be sure to tell the mechanic to check that. The TPS seems like it may be a likely culprit of the problem. Just so I know could someone tell me roughly where the TPS is located?

I think i forgot to mention it earlier. But this car has had the same problem twice now. Both times the problem has progressed from being a slight menace to making the car dangerous to drive. All in the matter of about a day or two. What I mean by this is at first when the problem starts to kick in the throttle will stick at about 35 and not release for a slight second. Later the throttle begins to stick mostly at about 2200-2800 RPMs and stay there for about 5-10 seconds, or until i lift the pedal up. Finally the car gets so that the throttle will stick at any speed and will not come up for 4+ minutes, regardless of efforts to lift the accelerator up.
 

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2003 DHS, 97 BMW Vert, 08 GMC Sierra Crew Cab
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87 Posts
Since these cars are not drive by wire, the other possibility is a frayed cable catching on the cable sheath. They can sometimes be very difficult to detect. All it takes is one strand of the cable being broken and out of place.
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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6,738 Posts
If in fact the TPS is moving even slightly, then the curb idle will be affected. Should be approx. 1/2 volt at idle then as the throtttle opens move gradually to 5 volts at wide open. If the throttle comes to rest and the TPS is say 2 volts, then the added fuel will raise the curb idle.
 

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98 seville sts
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I also had a problem with the throttle sticking open all i did was clean the intake with carb cleaner more offten its the egr on older cars lets carbon get built up on the throttle plate hinges. also try tapping lightly on the intake may loosen and unstick it for a while.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
:welcome: Brandon. This thread is just over 3 years old, good practice though. :thumbsup:
 
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