Hyundai Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter #1
Hey Everyone!
I've got a 2011 Santa Fe GLS AWD with the 3.5 and I'm pretty happy with it. It's got 114,000 miles and still going strong with only a few repairs and some maintenance needed since I bought it 18 months ago with 76k. One thing that is getting to me is a recent, significant drop in the gas mileage I've been getting. Up until about a month ago, I was getting around around 21.5 miles per gallon average with about 50/50 city/highway. Now, I'm lucky if I get 16.5. Even driving all highway, according to the trip computer which probably isn't very accurate, I average at best 20, whereas on a long trip down the PA turnpike a few months ago I averaged 27.
I've got no check engine light and no pending codes. The engine tends to make a lot of noise at idle, which I think is the lifters, but I don't think that would affect mileage. I know it's past due for spark plugs, but I would think if I lost a cylinder I'd be getting a misfire code. I use synthetic 5w20 with the OE filter, just replaced all four shocks, links and struts and I just had new LRR tires put on with an alignment. The only problems with the car as it stands are a front wheel bearing that's starting to make noise and the rear camber in both wheels is off -2 degrees, which can't be adjusted so something is screwed up there. The air filter is clean, I ran a bottle of Techron through the fuel system and I Seafoam'ed the intake to no avail. I don't have too much extra weight in the back and I'm not using the AC this time of year. I really don't know what it could be.
Any ideas?

Thanks Guys.
Joe
 

·
Registered
Joined
·
1,282 Posts
I'm not sure why the rear camber can't be adjusted since I just had mine aligned a month or two ago and that's one of the items on the alignment report.

Our engines have dampers in the intakes and variable valve timing features that, if I read the posts right, can cause problems with performance without throwing a code or having an obvious symptom (like a bad plug can). Maybe one of the resident experts can weigh in on that, but that's my first thought.

Please help us help you. Go to your profile and fill in everything marked by a pencil icon. What you enter will show up in the left margin of your posts.

.
 

·
Registered
Joined
·
6 Posts
Discussion Starter #3
Thanks for the heads-up. I filled out my info. Today I topped off the tank and then went for 25 mile drive, most of which was highway. I kept to 65mph, slowly accelerating and using the autostick to not rev the engine past 2500 up to 6th gear. For that trip I averaged 17 miles per gallon. A similar trip three months ago would have gotten me 24
 

·
Registered
Joined
·
3,036 Posts
In the past on a new 4 banger I bought millage was way off the suggest range. I kept bring it up in my barrage of visits for repairs on other failing parts and functions. One work order I notice it was looked into and an O2 sensor was changed! It was slow responding or something like that.
 

·
Registered
Joined
·
75 Posts
Change the plugs and see if that "moves the needle". Did mileage drop when new tires were added? I see they are LRR, just asking.
 

·
Registered
Joined
·
3,036 Posts
Plugs are the least likely and at that mileage they will be fine still!!

Its a fairly big job changing them hence I'd be looking elsewhere.

Check for codes and if the misfires don't exist then I'd move on. I am at 154,000km on original plugs and it still moves like a rabbit with a fox after it. Also computer L/km are good for it.

Using quality gas is important and if there is a lot of carbon build up due to crappy no name non Tier One Gas then. I'd focus on cleaning that up first. I will take a while. You saved nothing using cheap gas. No you pay to fix the problem and its at least a 100 times more costly.
 

·
Registered
Joined
·
188 Posts
Reinforcing Tripplec's reply about spark plugs:

I have 275,000 km (170,500 mi) on my 2007 Santa Fe 3.3 Limited AWD with original plugs. I am still getting 20.5 mpg, same mileage as new. Car starts quickly winter and summer and experiences no hesitation whatsoever. Plugs are NGK iridium. If yours are the same, your mileage should not vary.
 

·
Registered
Joined
·
6 Posts
Discussion Starter #8
The drop in mileage did not coincide with the new tires.
I recently threw my scanner on the car and was watching the live data while I was driving. The only things that looked off were that every once in awhile the pair of bank 1 O2 sensors would both read 0 volts for a second after going WOT, at WOT the throttle position would top off at 86.7%, and that short term fuel trim on both downstream sensors was pegged at 99.2% (though I suppose that makes sense if the catalyst is working properly)
 

·
Registered
Joined
·
24 Posts
When I saw a fuel drop like this in my old Ford Explorer, it was due to the coolant thermostat being stuck open. This happened like clockwork every five years. The only other symptom besides the change in fuel economy was a difference in the engine temperature gauge (which few people would notice) and I suppose the cabin heat. I don't know if relevant to the Santa Fe, but it's a thought.
 
1 - 9 of 9 Posts
Top