Hey guys I need yalls help! Im an experienced tech amd never seen anything like this.. I have a 2004 Hyundai sonata gls v6 automatic. It all started with a wobble on the harmonic balancer... Replaced balancer, I noticed 3 outta 4 motor mounts were blown. Replaced motor mounts' and ever since then after it warms up it goes into lymph mode, with no power throttles high to loe and back runs very rich and back fires so far i have replaced coolant temperature sensor crank shaft sensor all 4 o2 sensors. TPS. Fixed all vaccum leaks checked all fuses and relays I get no check engine light and is throttlingjing codes for high voltage and high heat on all 4 o2ensors and misfire on cylindee e

 

First thoughts,
If this problem was not present before you did all the work,then there is a good possibility you left off a ground wire someplace or , pinched a wire somewhere.
What might help would be to SLOWLY recheck your work . We have all been there at one time or another and it is probably something simple that you might have overlooked.

 

Check wiring for O2 sensors.
When engine is cold, the ECU uses a fuel map in open loop
When engine is warmed up, engine goes into closed loop and uses O2 sensor readings
This is when it goes into limp home mode.
ECU sees a problem with O2 readings and disable engine performance to limit possible damage
Looks like the O2 sensors were not the right type or wiring issue

 

Seems like another person who just dropped their questions
And they do not care if anyone else could use the answers they found