Engine replaced at 87533 miles (long block). At 106,812 miles the engine started to stumble at idle dropping about 50 rpm intermittently. Sometimes it won't do it for 10-15 minutes. Once in a while it will also surge up to 1100rpm and immediately drops back down. There is no check engine light. Using AI I methodically replaced the following parts.
plugs
coils
battery
high pressure fuel pump
throttle body (imbedded TPS/MAF)
Acceleration Position Sensor
temp sensor
fuel rail
fuel injectors
air filter
PCV
I disconnected O2 sensor (primary and secondar) one at a time and the engine check light came on immediately in both instances. I assume they are working.
I used an OBD II tester to check live settings (I do not know all of what they mean. but was checking for catalytic temperature since AI suggested that if the temp was too high it might indicate a blockage [temp was 890 and Hyundai specs say between 800-1100 is normal]).
Dealer couldn't find a problem/source and said since some of the parts I used were not Hyundai OEM (E3 plugs) they wouldn't go any further with diagnostics. What rot.
plugs
coils
battery
high pressure fuel pump
throttle body (imbedded TPS/MAF)
Acceleration Position Sensor
temp sensor
fuel rail
fuel injectors
air filter
PCV
I disconnected O2 sensor (primary and secondar) one at a time and the engine check light came on immediately in both instances. I assume they are working.
I used an OBD II tester to check live settings (I do not know all of what they mean. but was checking for catalytic temperature since AI suggested that if the temp was too high it might indicate a blockage [temp was 890 and Hyundai specs say between 800-1100 is normal]).
Dealer couldn't find a problem/source and said since some of the parts I used were not Hyundai OEM (E3 plugs) they wouldn't go any further with diagnostics. What rot.
Jun 14, 2025 at 3:27 PM
