Throttle position sensor

[Cable_Guy]

I have a 2001 Mercury Optimax 225, went to start up motor and now it’s idling at like 3000rpms, it didn’t do this last weekend, when I unplug the TPS idling goes back to normal but soon as I plug it back in it goes back to 3000rpms, just wondering if it is the TPS or could it be computer?

 

[tpenfield]

Based on your 'testing', I'd be starting with the TPS and work from there.

Do you have the computer diagnostics to check the engine out? or access to one?

 

[boscoe99]

TPS would be more likely between the two. Simple enough to measure input and output voltages to and from the TPS. Then make sure the output voltages can find their way to the ECU.

 

[Cable_Guy]

Got a new/used tps but now when that’s hooked up I get no response it’s like it’s not even plugged in? Ugh wondering if I got a bad tps ? It was used

 

[tpenfield]

Used is probably broken. Why would you get a used one?

 

[vroom ZOOM]

I have a 2001 Mercury Optimax 225, went to start up motor and now it’s idling at like 3000rpms, it didn’t do this last weekend, when I unplug the TPS idling goes back to normal but soon as I plug it back in it goes back to 3000rpms, just wondering if it is the TPS or could it be computer?

another cause for crazy idle in an optimax is if the fuel/air pressure regulator diaphragm has a hole, it will start dumping fuel into the air rail and make your engine run away... doesn't take much. This is easy to check, press the air side schrader valve and see if there is anything but air in there. If there is fuel as well, you know what to look for.