My Sante Fe drives beaufifully until it gets to about 50 - then it starts cutting out and deaccelerating. It seems as if it is not getting any power at all. It chugs out, powers back at the next lower gear, then settles in at about 45 mph.
Sounds an awful lot like a plugged catalytic converter to me. Take the car somewhere that can do a back pressure test to diagnose this. The DIY method is to either disconnect the exhaust pipe from the manifold or elsewhere upstream of the catalytic converter or to remove the upstream oxygen sensor, whichever happens to be easier. Drive the car (it will be loud and obnoxious and may turn on the check engine light), and if you can suddenly go more than 50 miles per hour, that tells you your exhaust system is plugged, and it’s probably the catalytic converter.
Do You Settle In At About 45mph, Too Or Is This Problematic ?
Seriously, any “Check Engine” light or DTCs (diagnostic trouble codes) ?
Do you have a 3.5L engine ?
Hyundai’s Technical Service Bulletins (written for their technicians) are very difficult for me to comprehend, but they’ve got at least one (8 pages) that discusses problems with the ETS (Electronic Throttle System) in 2001 - 2005 Sata Fe 3.5L vehicles.
Could be what we have here is a lack of communication between the gas pedal and the engine.
Any “Check Engine” light or DTCs (diagnostic trouble codes) ?
Do you have a 3.5L engine ?
CSA
The “Check Engine” light has not come on at all. It’s a 4 cyl. engine. Someone mentioned a possible crankshaft problem - does this seem likely?