I am completely stumped by these codes and, frankly, so is the dealer. I bought my 05 Tucson, second owner, two years ago and thankfully got the extended warranty.
Back Story:
Within two months after buying it, I was coming back home on the interstate and got stuck in bumper to bumper traffic that had the freeway backed up for at least 3 hours going up a mountain grade due to an accident. When I got going, I had a really bad misfire and couldn't go faster than 30 MPH uphill. I had truckers passing me. When I got to the top, I pulled over and the engine was shaking bad. Being an hour from home, I waited at the rest area for about 30 minutes. I restarted it and the misfire was gone but the CEL was on. I called the dealer and took it in the next day. Bank 1 & 2 Front O2 Sensors were replaced and plug/wires replaced. Everything is peachy, no issues.
About 3 months ago, CEL came back on: Codes P0170 and P0174. Took it to the dealer, they replaced the MAF sensor, the downpipe O2 sensors. A month later, CEL came back, same codes. The dealer found a large vacuum leak in the intake and replaced all vacuum lines, upper intake manifold, gaskets, and another tank (can't remember the name of it). Within two weeks after that, engine light came back, same codes. Dealer was stumped. They called Hyundai and they did the diagnostic and found there was ethanol corrosion in the fuel lines, fuel rail, and injectors clogged. All of the items replaced under warranty.
Last week, after my extended warranty expired the CEL came back on again.
I did some research and it says to check for clogged injectors, dirty MAF and air filter, or intake leak. At this point, everything that points to fixing the CEL codes have all been fixed.
The weird thing is that if I drive a 70 mile a day commute, I get no CEL. I leave town to go to Phoenix or Flagstaff (much lower and higher elevations) and it pops the codes. I just replaced the air filter last week and cleaned the MAF with MAF cleaner, ran through some seafoam in the gas and the engine and I still get the code when changing elevations. I am at wits end with fixing it. I am not suffering fuel economy as I am getting around 20-21 MPG verified through my OBDII scanner and monitoring it manually (EPA lists 05 2.7 4WD Auto combined economy as 19). I did get a cutout at around 5500RPM before the engine up-shifts during heavy acceleration, no issues otherwise and seems to have gone away after I seafoamed it.
Any ideas? I leave on Friday for a 2500 mile trip to NY.
Back Story:
Within two months after buying it, I was coming back home on the interstate and got stuck in bumper to bumper traffic that had the freeway backed up for at least 3 hours going up a mountain grade due to an accident. When I got going, I had a really bad misfire and couldn't go faster than 30 MPH uphill. I had truckers passing me. When I got to the top, I pulled over and the engine was shaking bad. Being an hour from home, I waited at the rest area for about 30 minutes. I restarted it and the misfire was gone but the CEL was on. I called the dealer and took it in the next day. Bank 1 & 2 Front O2 Sensors were replaced and plug/wires replaced. Everything is peachy, no issues.
About 3 months ago, CEL came back on: Codes P0170 and P0174. Took it to the dealer, they replaced the MAF sensor, the downpipe O2 sensors. A month later, CEL came back, same codes. The dealer found a large vacuum leak in the intake and replaced all vacuum lines, upper intake manifold, gaskets, and another tank (can't remember the name of it). Within two weeks after that, engine light came back, same codes. Dealer was stumped. They called Hyundai and they did the diagnostic and found there was ethanol corrosion in the fuel lines, fuel rail, and injectors clogged. All of the items replaced under warranty.
Last week, after my extended warranty expired the CEL came back on again.
I did some research and it says to check for clogged injectors, dirty MAF and air filter, or intake leak. At this point, everything that points to fixing the CEL codes have all been fixed.
The weird thing is that if I drive a 70 mile a day commute, I get no CEL. I leave town to go to Phoenix or Flagstaff (much lower and higher elevations) and it pops the codes. I just replaced the air filter last week and cleaned the MAF with MAF cleaner, ran through some seafoam in the gas and the engine and I still get the code when changing elevations. I am at wits end with fixing it. I am not suffering fuel economy as I am getting around 20-21 MPG verified through my OBDII scanner and monitoring it manually (EPA lists 05 2.7 4WD Auto combined economy as 19). I did get a cutout at around 5500RPM before the engine up-shifts during heavy acceleration, no issues otherwise and seems to have gone away after I seafoamed it.
Any ideas? I leave on Friday for a 2500 mile trip to NY.
