catalytic converter

[dmunz2]

I had a remanufactured engine installed in my 97 ford ranger. The idle will not slow down when I let my foot off the accelerator. the computer is sensing that the engine needs to keep the rpms up by something. the check engine light came on and then went off [x3] I am going to have the code read. would the catalytic converter outlet sensor be sending a signal the rpms need to stay up to clear the catalytic converter?? there is a different smell than before the engine was replaced.

 

[Mark_88]

As far as I know, the only thing that will raise RPMs is the temp sensor telling the computer that it is in warm up mode...or the throttle is stuck...

 

[adsm08]

Not even a remote possibility that the cat monitor is causing this. That sensor's only purpose is to monitor the amount of free oxygen after the cat to see if the cats are doing their job correctly.

Nothing in the exhaust can cause a high idle. Engine RPM is 100% determined on the intake side. Either it thinks it is too cold and staying in warm-up mode, or air is leaking in somewhere that it shouldn't, a loose vacuum line, a sticking throttle, or bad intake gaskets,