I have experienced the Loss of Power issue twice now and both under similar circumstances. Driving home to Canada from vacation a few weeks ago, we were 3 hours into the journey, fully loaded and driving uphill through the hills in north central Pensylvannia. It was 95 degrees outside and suddenly while pulling out into the passing lane to get around a slower truck the car just totally lost engine power. It didn't stall but there was no acceleration. Coasted to the shoulder and the car was idling unevenly and engine would not rev cleanly even in Neutral. Shut it off and back on a couple of times until it seemed to allow the engine to rev more freely. I was able to pull away slowly and get back up to highway speeds but any sharp acceleration would cause the engine to falter. By this time the Check Engine light was on. We carried on like this all the way home with fingers crossed. Fuel mileage was terrible using about 1/3 more fuel than normal for the last part of the journey. Dealer pulled codes that suggested Overfuelling but could not pin-point the cause. By this time CE light was out and car was running normally (of course
).
Two weeks later I had to make another trip to central PA and coming home in 97 deg. weather the car ran fine for the first 2 hours then on an uphill section just south of Williamsport the exact same thing happened. I managed to get over the crest of the hill and coast down the other side into Williamsport. Limped into the dealer (by now the car was virtually undrivable) and they diagnosed Lean Running on all cylinders. They checked all the sensors and they seemed OK. Suspecting fuel starvation they checked the fuel-pump pressure and it read normal (55psi). The tech then removed and cleaned the Mass Airflow Sensor and cleaned it, although it didn't seem to be dirty. He took it for a test drive and said everthing now appeared normal. By now it was cooler (79deg.F) so I decided to try for home and the car ran fine.
What bothers me is that two dealers have been unable to find an exact cause, each had totally opposite diagnosis and I'm left wondering if I can trust driving my car in 90 degree weather anymore!
Still love the car but...... Lastly, I cannot say enough good things about Fairfield Auto Mall in Montoursville PA (Authorised Hyundai Service Centre) who really came to my rescue and got me back on the road in a short time, despite being busy with service appointments.
