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1996 Deville Concours sticky throttle


debartz

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Hi Everyone,

I'm new to this site and wanted to ask if anybody has had an issue with the throttle or accelerator sticking? I onw a 1996 Deville Concours with the 4.6 Northstar engine. A few days ago the battery died and I had to jump start it. Then I took it to my mechanic to get the rear brakes replaced. On the way home from his shop I noticed that the engine idle seemed to be higher than normal. By the time I got home it was running very fast. I had to use two feet on the brakes to stop it. WOW, I put it in park and the engine was racing. I looked at the linkage and it seemed ok. Turned it off. Next day my mechanic came to my house and couldn't find anything wrong. Drove it again to his shop, this time engine speed was normal. He checked everything he could but couldn't find anything. Again I picked up the car and by the time I got 6 blocks away it was doing the same thing.

Any ideas???

Don

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Eventually mechanical throttle cables will stick or bind. I had a similar episode with my 96 STS and replacing the throttle cable cured it.

Bruce

2023 Cadillac CT4-V Blackwing

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Eventually mechanical throttle cables will stick or bind. I had a similar episode with my 96 STS and replacing the throttle cable cured it.

Thanks Bruce, I guess I'll have to replace it. Although when I was checking it out all the cables seemed to be ok and I could move them by hand.

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Before you replace the cable clean the throttle body really good, I had a 96 Deville that every 2 or so years would get to a point where the RPMS would run 1300 in DRIVE.

Cleaned the throttle body and throttle plate and it will return to normal

For the record, if you put the car in Neutral when that happens and VERY QUICKLY TROMP the accelerator to the floor and RELEASE IT it will settle the idle down, this is related to the throttle plate sticking

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Before you replace the cable clean the throttle body really good, I had a 96 Deville that every 2 or so years would get to a point where the RPMS would run 1300 in DRIVE.

Cleaned the throttle body and throttle plate and it will return to normal

For the record, if you put the car in Neutral when that happens and VERY QUICKLY TROMP the accelerator to the floor and RELEASE IT it will settle the idle down, this is related to the throttle plate sticking

Thanks,

Question, might sound dumb but how do I get to the throttle bdot and plate? I'm somewhat mechanical meaning I used to do my own work on all my cars but today it is like a nightmire even opening the hood.

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Ok its not hard, from my memory, you will need to remove the snorkle that runs from the air filter box to the black MAF 'collar', disconnect the MAF connector, then remove the 4 bolts that hold the collar on to the TB, and the TB plate and throat will be right there.

To the left is the IAC, it looks like the size of a 35mm roll of film with an electrical connector and two screws (torx screws), its at about 10 o'clock on the throttle body. Remove the IAC and clean the pindle and the port it sits in..

I use GM upper engine cleaner, a detail brush and lots of rags, be sure to clean the back of the plate, hold it open and get the throat really good all around and make sure you get the edges of the plate. It should take you 30 minutes to clean the plate, throat and IAC. Take your time it will be worth it, throttle response will be greatly improved.

Disconnect the negative terminal of the battery when its clean, to force the system to go through a relearn.

DO NOT put too much carb cleaner in the TB, use it on rags, brushes etc. Dont pour or spray it in.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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  • 3 weeks later...

Ok its not hard, from my memory, you will need to remove the snorkle that runs from the air filter box to the black MAF 'collar', disconnect the MAF connector, then remove the 4 bolts that hold the collar on to the TB, and the TB plate and throat will be right there.

To the left is the IAC, it looks like the size of a 35mm roll of film with an electrical connector and two screws (torx screws), its at about 10 o'clock on the throttle body. Remove the IAC and clean the pindle and the port it sits in..

I use GM upper engine cleaner, a detail brush and lots of rags, be sure to clean the back of the plate, hold it open and get the throat really good all around and make sure you get the edges of the plate. It should take you 30 minutes to clean the plate, throat and IAC. Take your time it will be worth it, throttle response will be greatly improved.

Disconnect the negative terminal of the battery when its clean, to force the system to go through a relearn.

DO NOT put too much carb cleaner in the TB, use it on rags, brushes etc. Dont pour or spray it in.

Thanks for the info. Sorry, but I just got bacl from vacation. Could the problem be the throttle sensor?

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Ok its not hard, from my memory, you will need to remove the snorkle that runs from the air filter box to the black MAF 'collar', disconnect the MAF connector, then remove the 4 bolts that hold the collar on to the TB, and the TB plate and throat will be right there.

To the left is the IAC, it looks like the size of a 35mm roll of film with an electrical connector and two screws (torx screws), its at about 10 o'clock on the throttle body. Remove the IAC and clean the pindle and the port it sits in..

I use GM upper engine cleaner, a detail brush and lots of rags, be sure to clean the back of the plate, hold it open and get the throat really good all around and make sure you get the edges of the plate. It should take you 30 minutes to clean the plate, throat and IAC. Take your time it will be worth it, throttle response will be greatly improved.

Disconnect the negative terminal of the battery when its clean, to force the system to go through a relearn.

DO NOT put too much carb cleaner in the TB, use it on rags, brushes etc. Dont pour or spray it in.

Thanks for the info. Sorry, but I just got bacl from vacation. Could the problem be the throttle sensor?

As Ranger noted its probably a dirty throttle body and plate, but check for codes a TPS or IAC would set a code

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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