2010 Hyundai Elantra Fuel System Problems

CHECK ENGINE LIGHT CAME ON UPON RESEARCH I FOUND OUT IT COULD BE THE EVAP EMISSION CONTROL SYSTEM PRES SENSOR LOW IT IS UNKOWN AS TO WHAT ELSE THIS ENCOMPASSES

CAR SLAMS AND SHIFTS TO 3RD GEAR OVER 60 MILES IN MOTION AND FREEZES AT THAT SPEED. ADVANCED TESTS HAVE BEEN DON FULL TRANSMICION AND OTHER TESTS HAVE BEEN TESTED AND NO CAUSE HAS BEEN FOUND DIFFERENT CODES COME UP LIKE 734, ALL PIECES WORKING PROPERLY AND I CHANCHED TO NEW ONES AN ISSUE CONTINUES

I WAS APPROACHING HIGHWAY FROM CITY ROADS AND I HAD TO ACCELERATE TO GET IN THE FLOW. SUDDENLY, I FELT THAT EVEN THOUGH I WAS ACCELERATING, CAR DID NOT GAIN SPEED. I CHECKED RPMS AND IT WAS QUITE HIGH FOR THE SPEED THAT CAR WAS MOVING. IT LOOKED TO ME AS IF CAR WAS IN NEUTRAL GEAR BUT IT WAS NOT. THE CAR BEHIND ME ALMOST HIT MY CAR BECAUSE THE DRIVER WAS EXPECTING MY CAR TO MOVE FASTER. I HAD TO STOP ON SHOULDER TO CHECK WHAT IS HAPPENING. I HAD THIS KIND OF EXPERIENCE BEFORE TOO BUT NOT LIKE THIS ONE. THEN IT HAPPENED AGAIN WHEN I GOT OFF THE HIGHWAY AND I WAS BACK IN CITY TRAFFIC. WHAT MY OBSERVATION IS, THAT WHEN THE AUTOMATIC TRANSMISSION GOES FROM 2ND GEAR TO 3RD, THERE IS A PROBLEM. WHEN I BOUGHT THE CAR, EVEN THEN THE TRANSMISSION WAS NOT SMOOTH BUT THERE WAS NO PROBLEM LIKE THE ONE I MENTIONED EARLIER. BUT AS THE MILEAGE IS INCREASING, THE PROBLEM IS GETTING BIGGER TOO. I DO REGULAR OIL CHANGE AS I HAVE PURCHASED SERVICE PLAN WHEN BUYING THE CAR. I HAD COMPLAINED TO THE DEALER SERVICE REPRESENTATIVE ABOUT IT(TRANSMISSION HAVING PROBLEM) COUPLE OF TIMES BUT THEY SAID THEY DID NOT FEEL IT. I THINK THEY WERE NEGLECTING THE PROBLEM BECAUSE THERE IS PROBLEM WITH TRANSMISSION AND THAT COSTS A BIG AMOUNT. I FEEL THAT THIS IS A BIG PROBLEM EVEN THOUGH I AM NOT AN EXPERT. *TR

WHEN DRIVING AT HIGHWAY SPEEDS, THE TRANSMISSION SLIPS OUT OF GEAR AND THE RPMS GO SKY HIGH AND THE CAR RUNS LIKE IT IS IN NEUTRAL. I HAVE TO TAP THE BRAKE BEFORE IT WILL ADJUST AND GO BACK INTO GEAR. THIS SEEMS TO BE A BIGGER PROBLEM WHEN CARRYING PASSENGERS. THE ADDED WEIGHT APPEARS TO BE A FACTOR. IT'S RATHER DANGEROUS SINCE IT CAN HAPPEN AT ANY TIME WITHOUT WARNING AND HAPPENED JUST THIS PAST WEEKEND WHEN DRIVING IN MINNEAPOLIS, MN IN HEAVY TRAFFIC. MILEAGE REPORTED IS ESTIMATED FOR WHEN I FIRST NOTED THIS PROBLEM APPROXIMATELY A YEAR AGO. NOT KNOWING A LOT ABOUT CARS, I DIDN'T THINK TO REPORT IT. WHEN I FIRST BOUGHT THE CAR, I WAS TYPICALLY DRIVING FROM HOME TO WORK AND BACK, BUT HAVE BEEN TRAVELING MORE FREQUENTLY IN THE LAST YEAR DUE TO FAMILY ACTIVITIES. THE PROBLEM OCCURS MORE OFTEN ON LONGER TRIPS. *TR