Doesn’t decelerate when off the throttle

[greenz28]

I have a weird problem. When off the throttle the car goes by itself, it doesn’t pick up speed, but will try to stay a constant speed even with my foot completely off the pedal. Once stopped it’ll slowly drop back down to the correct idle rpm. It does it at all speeds. We’ve replaced the tps and iac with no change. I’m wondering now if it’s in the tune. If so, any idea where I should look in tunerpro?

[harner]

Stock throttle body?

[greenz28]

Stock throttle body?

No, 52mm throttle body. It’s a ported stocker if I remember correctly.

[ElkySS]

Throttle cable. pull it off the tb and see if it move freely

[Catmaigne]

Either the throttle blades are misadjusted, or the TPS is. You need to scan the car though and find out what TPS % the pcm is seeing, that's the only way you'll really know. I'm guessing it's not returning to 0% on coast, so you never hit engine braking.

Sometimes you have to elongate the mounting holes in the TPS to get the voltage low enough, especially on cheap aftermarket sensors.

[greenz28]

Throttle cable. pull it off the tb and see if it move freely

The cable seems to be working properly.


Either the throttle blades are misadjusted, or the TPS is. You need to scan the car though and find out what TPS % the pcm is seeing, that's the only way you'll really know. I'm guessing it's not returning to 0% on coast, so you never hit engine braking.

Sometimes you have to elongate the mounting holes in the TPS to get the voltage low enough, especially on cheap aftermarket sensors.

I'll give this a try. TPS should read 0% all the time when off the pedal?

[Injuneer]

The cable seems to be working properly.



I'll give this a try. TPS should read 0% all the time when off the pedal?

Yes

[rentedmule]

I had a ported stock TB that was worn out and the blades would stick open. You should be able to see the witness mark on one edge of the TB bore if it's scraping.